GIT Patho Flashcards
1
Q
What is a polyp?
A
Fleshy protuberant growth on an epithelial surface
2
Q
What are the 2 growth patterns of polyps?
A
1) Pedunculated
2) Sessile (no stalk)
3
Q
(Pedunculated/sessile) polyps can be removed by looping a snare to cauterise the stalk.
A
Pedunculated (have stalk)
4
Q
(Pedunculated/sessile) polyps can be removed by injecting saline into the submucosa to elevate the poly and facilitate snaring.
A
Sessile (no stalk, need to elevate)
5
Q
What are 5 categories of polyp/lesions?
A
1) Neoplastic (carcinoid, adenomatous carcinoma)
2) Hyperplastic/inflammatory (eg. gastritis, sites of repair, cardiac, inflammatory fibroid)
3) Hamartomatous/development (eg. pancreatic heterotopia, fundic-gland polyp, peutz-jeghers)
4) Mesenchymal (eg. native cell type tumours)
5) Misc. (eg. xanthoma, lymphoma, hemangioma)
6
Q
Fundic gland polyps are (benign/malignant) and consist of which 2 types?
A
Benign
1) Sporadic (eg. PPI Rx)
2) Familial (eg. FAP, Gardner’s syndrome)
7
Q
What are the macroscopic and microscopic features of fundic gland polyps?
A
Macro: 1/multiple bumps
Microscopic:
1) Dilated glands
2) Microcysts lined by oxyntic epithelium
3) Shortened foveola
4) ↑smooth muscle bundles in LP
5) no proliferation of foveolar epithelium
8
Q
What are 2 associations of fundic gland polyps?
A
1) ↓acidity
2) Hypergastrinemia → oxyntic-glandular hyperplasia
9
Q
Hyperplastic polyps are often (benign/malignant) and are very common in px in their 50s-60s, preceding _________, formed as a regenerative response to injury.
A
Benign
Precedes chronic erosive gastritis
10
Q
What are the macroscopic and microscopic features of hyperplastic polyps?
A
Macroscopic:
1) Bumps (<1cm)
2) Surface erosions ±bleeding
3) multiple polyps in gastric atrophy
Microscopic:
1) Elongated/ tortuous/ dilated gastric foveolae w pyloric/fundus glands
2) LP has inflammatory cells, scattered smooth muscles bundles, edema, patchy necrosis
3) Surface mucosa regenerative changes due to ulceration
11
Q
What is a gastric adenocarcinoma?
A
Malignant neoplasm showing GI glandular epithelial differentiation
12
Q
True or false: Gastric carcinoma is
* Commoner in Asia than in the West
* Ave. age of diagnosis is 7th decade of life
* One of the leading causes of cancer deaths
worldwide due to tendency for late clinical
presentation and poor response to
conventional chemotherapy
* 5 year survival is 10-15% overall; but 95% for
subset of surgically treated early gastric
carcinoma
A
True
13
Q
What are 5 symptoms of gastric adenocarcinoma?
A
1) WL
2) Abdo pain
3) Anorexia
4) Vomiting
5) Altered bowel habits
Less common
6) Dysphagia
7) Anaemic symptoms
8) Haemorrhage
14
Q
How is early gastric cancer differentiated from late?
A
Invaded no more deeply than the submucosa, irrespective of lymph node metastasis
15
Q
What does the prognosis of gastric carcinoma depend on?
A
1) Depth of invasion
2) Extent of nodal and distant metastasis
16
Q
What is the standard treatment option for gastric carcinoma?
A
Surgical resection
17
Q
What are 3 macroscopic growth patterns of gastric carcinoma (evident at both early and advanced stages)?
A
1) Exophytic (protrusion of mass into lumen)
2) Flat/depressed (no obvious mass in mucosa)
3) Excavated (erosive crater present in wall of stomach)
18
Q
How is a gastric carcinoma different from a bleeding/chronic peptic ulcer macroscopically?
A
Peptic ulcer:
- flat ulcer edge level w remaining stomach
- Straight vertical edges
- haemorrhage/flat clean base
19
Q
What are the 3 subtypes of GI adenocarcinomas?
A
1) Intestinal (53%)
- associated w chronic atrophic gastritis, severe intestinal metaplasia, dysplasia
2) Diffuse (33%)
- younger px
- proximal stomach
- poorly differentiated carcinomas
3) Unclassified (14%)
20
Q
What is the main histological feature of intestinal type adenocarcinoma?
A
Well formed glands lined by cuboidal/columnar epithelial
21
Q
Where do intestinal type adenocarcinomas arise from?
A
Majority from complete-type intestinal metaplasia
(pattern of genetic alterations resembles colonic carcinoma)
22
Q
What is the main histological feature of diffuse type adenocarcinoma?
A
1) Individual/poorly formed nests of cells growing in an infiltrative pattern
2) Signet ring cells
23
Q
Where do diffuse type GIT adenocarcinomas arise from?
A
Directly from gastric foveolar epithelium
24
Q
What is the main macroscopic feature of diffuse type adenocarcinoma?
A
“Leather bottle” appearance
- extensive infiltration of malignancy, creating a rigid, thicken linitis plastica
25
Which parts of the stomach are gastric carcinomas most common?
Pylorus and antrum > Cardia
Lesser curve > Greater
26
What is the most important prognosis factor for gastric carcinomas?
Depth of invasion
27
Where do gastric carcinomas most often spread to?
1) Oesophagus (proximal carcinoma)
2) Duodenum (distal carcinoma)
3) Omentum, colon, pancreas, spleen
Death by widespread seeding to:
4) Peritoneum
5) Lung/Liver
6) Adrenal gland, ovary, spleen
First clinical manifestation:
7) Supraclavicular nodes (Virchow's nice, Trousseau's sign)
28
What is the difference between hamartomatous and adenomatous polyp?
Hamartomatous
- Non-cancerous growths.
- Arise from disorganized overgrowth of normal tissue.
- Typically do not progress to cancer.
- Often associated with genetic syndromes.
Adenomatous Polyps:
- Considered pre-cancerous growths.
- Arise from glandular tissue in the colon or rectum.
- Have the potential to develop into colorectal cancer if left untreated.
29
What is Peutz-Jeghers syndrome?
Genetic condition of hamartomatous polyps
- associated with ↑pigmentation around lips, genitalia, buccal mucosa, feet and hands
- polyps carry very little malignant potential
30
What are GI adenomas?
Benign epithelial neoplastic polyps composed of proliferating neoplastic glands.
31
What are 3 growth patterns of GI adenomas?
1) Tubular adenoma (tubular invaginations)
2) Villous adenoma (finger-like projections)
3) Tubulovillous adenoma
32
What are serrated polyps?
Polyps with saw-toothed microscopic appearance
- arise in colon
- may become cancerous
- small in distal (hyperplastic polyps): rarely malignant
- large: precancerous and difficult to remove
33
What are 3 major molecular pathways that lead to colorectal cancer via adenomatous polyps?
1) Oncogene/TS gene mutation (eg. APC, KRAS, BRAF, TP53)
2) Microsatellite instability (MMR deficiency)
3) CpG island methylation pathway (CIMP)
34
What are 3 gross findings of colorectal cancer?
1) Polypoidal, fungated, ulcerated appearance
2) Larger tumours predominated in proximal colon
3) Circumferential growth/apple core lesions in distal colon
35
Colorectal cancer tumours in the proximal colon tend to grow as ______________ masses that extend along 1 wall of capacious cecum and ascending colon (obstruction is uncommon).
Colorectal cancer tumours in proximal colon
→ polypoid, exophytic masses
36
When carcinomas in the distal colon are discovered, they tend to be _____________ lesions that produce _____________________ constrictions of the bowel.
Carcinoma in distal colon
→ annular, encircling lesions
→ produce napkin-ring constrictions
37
What are 9 clinical presentations of colorectal cancer?
1) Abdo pain
2) Altered bowel habits
3) Per-rectal bleeding
4) Asymptomatic
5) Fistulation
6) Weakness
7) Anemia
8) Weight loss
9) Obstruction
10) Others
38
What are 4 histological findings on CRC?
1) Well to poor differentiated of tubule formation
2) prominent desmoplastic (fibrotic tissue) response
3) Abundant intraluminal eosinophilic necrotic debris (outgrowth vascular supply)
4) Extracellular mucin pools (mucinous type carcinoma)
39
What is the most common type of GI cancer?
Colon adenocarcinoma
40
True or false: Colon adenocarcinomas:
* begins in the cells of colonic crypts and spreads first through the wall of the colon and potentially into the lymphatic system and other organs.
* Colon adenocarcinoma can be treated, with 50% of
patients surviving for at least five years.
* Early-stage colon cancers have 5 yr survival rates of
70 to 80%.
* These tend to present as cancers arising in
polyps and be cured but surgical resection.
True
41
What are 2 genetic conditions that predispose an individual to colon adenocarcinoma?
FAP and Gardner's syndrome
(↑ polyps → ↑risk)
42
How does a normal mucosa progress to a carcinoma?
1) Normal mucosa:
- 1st hit: germline/somatic mutation of TS genes (eg. APC @ 5q21)
2) Mucosa @ risk:
- Methylation → inactivation of TS/protooncogenes (eg. APC, ß-catenin)
3) Early adenoma:
- Protooncogene mutation (KRAS @ 12p12)
4) Late adenoma:
- LOH @ 18q21 (SMAD 2 and 4)
5) Carcinoma:
- homozygous loss of TS genes (TP 53)
6) Tumour progression + metastasis
- additional mutations
- gross chromosomal alterations
43
What is the difference in the criteria for invasive stomach vs colonic carcinomas?
Stomach: invasion beyond basement membrane
Colon: invasion beyond muscular mucosae
44
True or false: Familial adenomatous polyposis:
* AD inheritance of APC gene (5q21)
* M=F
* Incidence 1:100,000
* 80-100% gene penetrance
* >95% of colonic polyposis by
age 35 - bleeding
* >90% chance of cancer by age
50 if untreated by colectomy
True
45
What is the name for neuroendocrine cell tumours in the GIT?
Carcinoids
46
Carcinoids are growths that look like (low/high) grade cancers but (frequently/infrequently) spread to other parts of the body.
Low grade
infrequently spread
47
What is carcinoid syndrome?
Overproduction of substances + metastasis of carcinoid into systemic circulation:
1) Flushing
2) Diarrhoea/+freq. of mvt
3) Bronchoconstriction
4) R cardiac valvular disease
5) Abdo cramps
6) Peripheral oedema
48
What are the gross appearance of Gastrointestinal Stromal Tumours?
Polypoidal intramural tumours
- ulcerate overlying GI mucosa
- rarely: separate masses in mesentery
49
What is the most common type of sarcoma in the GIT?
GISTs (made up of spindled cells)
50
What is used to diagnose GISTs?
IHC biomarkers:
1) CD117
2) CD34
3) DOG1
51
Where is the upper and lower GIT separated?
Duodenal-jejunum junction
52
What are 4 cardinal symptoms of GIT diseases?
1) Abdo/chest pain
2) Altered ingestion of food (eg. nausea, vomiting, dysphagia, anorexia)
3) Altered bowel movements (eg. diarrhoea, constipation)
4) GIT bleed
53
What are 4 common acute complications of GIT diseases?
1) Dehydration
2) Sepsis
3) Bleeding
4) Obstruction/Perforation
54
What is the main chronic complication of GIT diseases?
Malabsorption (malnutrition, deficiency states)
55
What is an ulcer?
Local defect of an organ/tissues surface produced by sloughing of inflamed necrotic tissue → breach in continuity of covering epithelium
56
What are the mucosal changes in an ulcer?
Patch-like w colour change
57
What are 6 causes of oral ulcers?
V
I - Candidiasis, HSV, HFMD
T - lip-biting, ill-fitting dentures
A - mucocutaneous disorders (eg. lichen planus, erythema multiforme), SLE, IBD
M
I - Aphthous ulcers
N - dysplasia, squamous cell carcinoma
C
D - cytotoxic chemo, B12/folate deficiency
E
58
What are aphthous ulcers (canker sores)?
Iatrogenic, common, small, painful, shallow ulcer
- superficial erosion, grey-white exudate w erythematous rim
- self-limiting
59
Oral candidiasis usually presents as ________________________, caused by ______________ and only leads to pathology when ________________________. In severe cases, it can __________________.
Oral candidiasis:
- adherent white, curd-like plaque on tongue→ underlying granular erythematous inflammatory base
- by Candida albicans
- only pathogenic in immunocompromised
- severe → spread to oesophagus/haematogenously
60
Herpetic stomatitis usually presents as _________________________, caused by __________________.
It is usually (symptomatic/asymptomatic) as ________________________. In severe cases, it can ___________.
It can be treated with __________________.
Herpetic stomatitis:
- small vesicles/blisters contain clear fluid around lips
- caused by HSV 1>>>>2
- asymptomatic in most adults as dormant within mouth ganglia, reactivated by fever, sun, cold, URTI, trauma and immunocompromised
- severe: multiple vesicles throughout oral cavity, lymphadenopathy, viraemia
- Treat w anti-virals eg. acyclovir
61
Lichen planus usually presents as ____________________, caused by ______________. It is treated with _______________________.
Lichen planus:
- Wickham striae, erosions, ulceration
- Inflammatory, uncertain aetiology ?T-cell mediated autoimmune
- Treatment: Steroids, immunosuppressants
62
Pemphigus vulgaris usually presents as ____________________, caused by ______________. It is treated with _______________________.
Pemphigus vulgaris:
- ulcers on the mouth
- Autoantibodies to desmosomal proteins → blisters
- Treatment: Steroids, immunosuppressants
63
What 3 types of mucosal change appearances in the mouth?
1) Leukoplakia
- whitish, well-defined mucosal patch (caused by epidermal thickening/hyperkeratosis)
2) Erythroplakia
- thin, friable, atropic mucosa with red, granular appearance
3) Speckled mucosa (red + white)
- “Combined” leuko-erythroplakia mucosal changes
64
Leukoplakia:
- (clinical/histological) syndrome
- presents as ______________
- most (benign/malignant)
Leukoplakia:
- clinical syndrome
- White patch or plaque that cannot be scraped off or characterized as any other disease, Vermilion border of lower lip, buccal mucosa, hard and soft palates
- most benign (3-25 % undergo transformation to invasive carcinoma)
65
What are 3 histological features of leukoplakia?
1) Banal hyperkeratosis without epithelial dysplasia
2) Mild to severe dysplasia/ Carcinoma in-situ
3) Invasive carcinoma
66
What are 3 things leukoplakia are most commonly associated with?
1 Tobacco
2) chronic friction
3) alcohol abuse
> common in older men
67
Erythroplakia:
- presents as ______________
- Red, velvety, often granular areas, may or may not be elevated
- Usually occurs at thin squamous mucosal sites: Lateral-ventral tongue, floor of mouth, palatine arch, retromolar trigone
68
What are 3 implications of erythroplakia?
1) Severe epithelial dysplasia
2) carcinoma-in-situ
3) invasive squamous cell carcinoma (majority)
69
What are 3 histological features of erythroplakia?
1) Epithelial dysplasia (> 50%)
2) Absence of keratin production and a reduced number of epithelial cells.
3) Since the underlying vascular structures are less hidden by epithelium,
erythroplakia appears red clinically.
70
What are 2 tumours that can arise from the oral/oropharyngeal surface squamous epithelium?
Benign: Squamous cell papilloma
Malignant: Squamous cell carcinoma
71
Oral/oropharyngeal squamous cell papilloma:
- most common (benign/malignant) epithelial neoplasm
- associated with ________virus
- found on ________________
Oral/oropharyngeal squamous cell papilloma:
- most common benign epithelial neoplasm
- associated with HPV virus
- found on uvula, palate, tongue, gingiva, lower lips, buccal mucosa
72
How is squamous cell papilloma treated?
local excision
73
What are the macroscopic features of squamous cell papilloma?
Solitary/multiple exophytic, warty, cauliflower-like lesions
74
What are the microscopic features of squamous cell papilloma?
Papillary projections of delicate fibrovascular cores surfaced by mature squamous epithelium
75
Oral/oropharyngeal squamous cell carcinoma:
- 95% of oral cavity cancers
- usually affect __________
- found on ________________
Oral/oropharyngeal squamous cell carcinoma:
- 95% of oral cavity cancers
- usually affect 50-70 years, 90% men
- found on floor of mouth, tongue, hard palate, base of tongue (areas constantly bathed in saliva and with thin non-keratinized squamous epithelium)
76
What are 5 factors that ↑the risk of squamous cell carcinoma and 1 factor that ↓ risk?
↓: fruit and veg consumption
↑:
1) Smoking
2) alcohol
3) tobacco chewing
4) betel chewing
5) HPV (esp. type 16)
77
What are the macroscopic features of squamous cell carcinoma?
Masses with necrosis, ulcers and rolled borders; induration is relatively specific for invasion
78
What are the microscopic features of squamous cell carcinoma?
May have keratinizing growth pattern, but moderate/marked atypia at base, irregular and infiltrative stromal invasion
79
What are 4 causes of sialadenitis?
1) Trauma
2) Viral: Mumps
3) Bacterial: Staph aureus, strep viridans
4) Autoimmune: Sjögren syndrome (dry mouth and eyes)
80
What are 4 association of Sialolithiasis: Calculi causing ductal obstruction (mostly in submandibular glands)?
1) Dehydration
2) trauma
3) smoking
4) gum disease
81
What are 6 neoplasms of the salivary glands?
(parotid>submandibular>sublingual and minor)
Benign: Pleomorphic adenoma (50%) >
Warthin tumor (5-10%)
Malignant:
Mucoepidermoid carcinoma (15%) > Adenocarcinoma (10%) >
Adenoid cystic carcinoma (5%) >
Acinic cell carcinoma (5%)
82
Pleomorphic adenoma:
- Benign epithelial tumor (______ tumor)
- Most common tumor of salivary
glands (10x more common in parotid)
- Average age of presentation: _____
- clinical presentation:__________
- (prone/not prone) to recurrence
- malignant transformation (rare/common)
Pleomorphic adenoma:
- Benign epithelial tumor (mixed tumor)
- Most common tumor of salivary glands (10x more common in parotid)
- Average age of presentation: 40
- clinical presentation: Painless, slow-growing mass in front of and below the ear (parotid)
- Prone to recurrence (no true capsule; avoid enucleation)
- Rarely can have malignant transformation (carcinoma ex-pleomorphic adenoma)
83
What are the macroscopic features of a pleomorphic adenoma?
Lobulated, solid mass with chondroid (firm, cartilaginous) and myxoid (soft, gelatinous) areas
84
What are the microscopic features of a pleomorphic adenoma?
1) Circumscribed, lobulated but unencapsulated
2) Epithelial (tubular structures) and stromal (greyish chondromyxoid stroma) components
85
Warthin tumour:
- (benign/malignant)
- 2nd most common salivary gland tumour (Almost exclusively in parotid gland, superficial lobe)
- Average age of presentation: _____
- more common in ______________
Warthin tumour:
- benign
- 2nd most common salivary gland tumour (Almost exclusively in parotid gland, superficial lobe)
- Average age of presentation: 50-70
- more common in M smokers
86
What are the macroscopic features of a warthin tumour?
Ovoid, encapsulated mass
- Cut sections show a solid-cystic interior that contains viscous yellow-brown fluid “motor oil”
87
What are the microscopic features of a warthin tumour?
1) well circumscribed mass
2) Dense lymphoid stroma
3) Tubular and papillary projections of epithelium, lined by 2 distinctive layers of oncocytic (abundant eosinophilic cytoplasm) cells
88
Oesophageal congenital disorders such as _________________________ and ___________________:
- present when?
- treat how?
- complications (3)
Oesophageal atresia, tracheo-oesophageal fistula
- present shortly after birth: regurgitation on feeding
- treatment: surgical repair
- complications:
1) Aspiration pneumonia
2) suffocation
3) fluid & electrolyte imbalances
89
Diaphragmatic hernia is __________________________________________ and can lead to: _____________________.
Incomplete formation of diaphragm → abdominal viscer herniate into thoracic cavity
Severe: pulmonary hypoplasia
90
How do oesophageal motility disorders (eg. nutcrack esophagus, corkscrew esophagus, achalasia) present?
1) Heartburn
2) Dysphagia
3) Frequent coughing/choking
91
What are 3 examples of esophageal motility disorders?
1) Nutcracker esophagus
2) Corkscrew esophagus
3) Achalasia
92
What is a nutcracker esophagus?
High amplitude, uncoordinated contractions of inner circular and outer longitudinal smooth muscle
93
How is a nutcracker esophagus diagnosed?
Manometry
94
What is a corkscrew esophagus?
Diffuse esophageal spasm:
Uncoordinated peristalsis with repetitive, simultaneous contractions (normal amplitude) of the distal oesophageal smooth muscle
95
What is achalasia?
Triad of incomplete lower oesophageal sphincter relaxation, increased lower oesophageal sphincter tone, and aperistalsis of the oesophagus
96
How is achalasia treated?
1) Myotomy
2) Pneumatic balloon dilatation
3) Botox injection
97
What are 3 causes of achalasia?
Primary:
1) Degenerative
Secondary
2) Chagas disease
3) Diabetic autonomic neuropathy
98
What are 2 examples of esophageal lacerations?
1) Mallory-Weiss tears:
- Longitudinal superficial mucosal tears near the GEJ
- a/w severe retching or vomiting secondary to acute alcohol intoxication
- no need surgical intervention
- present w: Haematemesis
Boerhaave syndrome:
- Less common, more severe barogenic injury due to sharp increase in intraluminal pressure
- Transmural tearing and rupture of the distal oesophagus
- Leads to severe mediastinitis and usually require surgery
- present w: Severe chest pain, tachypnea and shock
99
How are Mallory-Weiss tears and Boerhaave syndrome differentiated clinically and why is it important?
Mallory-Weiss: hematemesis
- no need surgery
Boerhaave syndrome: Severe chest pain, tachypnea, shock
- need surgery
100
What are oesphageal varices and how do they form?
Dilated tortuous vessels, usually submucosal, within the lower oesophagus and proximal stomach.
Pathogenesis:
Portal hypertension (eg. liver cirrhosis)
→ ↑ portal venous P → collateral channels @ portal-systemic anastomoses
→ congestion and dilatation
101
What are 2 possible complications of esophageal varices?
1) Hematemesis
2) Melena
102
What are 5 forms/etiologies of esophageal inflammation?
1) Reflux esophagitis (GERD)
2) Chemical
3) Infectious
4) Eosinophilic
5) Iatrogenic injury
103
What is the most common cause of esophagitis?
GERD
104
How does GERD present and what are 4 associated risk factors?
Clinical presentation:
1) Heartburn
2) Dysphagia
3) Postprandial regurgitation of sour-tasting gastric contents
4) Sore throat and cough
Risk factors:
1) Abrupt ↑ in abdo P (eg. coughing, bending)
2) Alcohol, tobacco
3) Obesity, pregnancy
4) Hiatus hernia
105
What is the possible complication for GERD?
Barrett esophagus in chronic GERD
106
What are 4 macroscopic and 4 microscopic features of GERD?
Macroscopic:
1) Normal
2) Hyperaemia
3) Erosions
4) Strictures
Microscopic:
1) Basal zone hyperplasia
2) Elongation of LP papillae
3) Erosions
4) Intraepithelial eosinophils
107
What is eosinophilic esophagitis and 3 macroscopic features?
Eosinophil-dominated inflammation a/w atopic disease
Macroscopic:
1) Feline esophagus
2) Linear furrows
3) Strictures
108
What is Barrett esophagus and what is it a/w?
Intestinal metaplasia in esophageal squamous mucosa (complication of chronic GERD)
- a/w ↑ risk of dysplasia and adenocarcinoma
109
What are 2 diagnostic criteria for barrett esophagus?
Endoscopy: Metaplastic columnar mucosa above GEJ
Microscopy: Intestinal-type metaplasia w goblet cells
110
What is the typical macroscopic appearance of barrett esophagus?
Tongues of red, velvety columnar mucosa extending upward from the GEJ, alternating with smooth, white squamous mucosa.
111
What are 5 malignant neoplasia of the esophagus?
1) Carcinomas: SCC, adenocarcinoma
2) Neuroendocrine carcinoma
3) Melanoma
4) Lymphoma
5) Sarcoma
112
What is an example of a benign esophageal neoplasm?
Leiomyoma (mesenchymal)
113
What are 3 clinical presentations of esophageal SCC?
1) Mass effect/Stricture: Dysphagia, odynophagia, obstruction
2) Ulceration: Haemorrhage, anaemia, sepsis
3) Systemic: Weight loss (impaired nutrition and tumour cachexia)
114
What are 2 macroscopic features of esophageal SCC?
Most common on middle to upper 2/3 of esophagus
1) Polyploid and exophytic
2) Ulcerating and diffusely infiltrative
115
What are 4 areas/methods esophageal SCC can spread?
1) Circumferential and longitudinal spread
2) Local invasion into adjacent structures:
- Respiratory tree (tracheo-oesophageal fistula) → aspiration pneumonia
- Aorta → catastrophic exsanguination
- Mediastinum → mediastinitis
3) Lymph node metastasis
- Upper third → cervical lymph nodes
- Middle third → mediastinal, paratracheal and tracheobronchial nodes
- Lower third → gastric and coeliac nodes
4) Distant metastasis
116
What are 3 risk factors and 1 protective factor for esophageal adenocarcinoma?
Risk factors:
1) Chronic GERD
2) Radiation
3) Tobacco
Protective:
Fruits and veg
117
What are 3 clinical presentations of esophageal adenocarcinoma?
1) Mass effect: Dysphagia, odynophagia, obstruction
2) Ulceration: Haemorrhage, anaemia, sepsis
3) Systemic: Weight loss (impaired nutrition and tumour cachexia)
118
What are the macroscopic features of adenocarcinoma?
Lower third of esophagus (may invade cardia)
Flat/raised patches → large mass or ulcerate, infiltrate
diffusely
119
What are 3 microscopic features of esophageal adenocarcinoma?
Mucin-producing, gland-forming:
1) Usually intestinal-type
2) Signet ring cells, poorly differentiated
3) Barrett’s (intestinal metaplasia) in the background
120
What are 2 causes of acquired pyloric stenosis?
Benign: antral gastritis/peptic ulcers close to pylorus
Malignant: Carcinoma of distal stomach/pancreas (via infiltration/fibrosis)
121
What are 3 risk factors for congenital hypertrophic pyloric stenosis?
1) FHx
2) Turner syndrome
3) Trisomy 18
4) Erythromycin/Azithromycin exposure
122
How does congenital hypertrophic pyloric stenosis present (i) clinically and (ii) on PE?
Clinical presentation: 3-6wk
- new onset regurgitation
- projective non-bilious vomiting after feeds
- frequent demands for refeeding
PE:
- Firm ovoid 1-2cm mass in epigastric region
- visible peristalsis
123
How is congenital hypertrophic pyloric stenosis treated?
Myotomy
124
What is the difference between gastritis and gastropathy?
Gastritis: + inflammation
- neutrophil infiltration
Gastropathy: - no inflammatory cells
125
What is are 2 ways that acute gastritis can present?
1) Asymptomatic:
- epigastric pain
- nausea and vomitting
2) Mucosal erosion, ulceration, hemorrhage → hematemesis, melena, Iron deficiency anemia
126
What are 6 causes of acute gastritis/peptic ulcers?
1) Age → ↓mucin and HCO3
2) Uraemia/H. pylori → ↓HCO3 by NH4+
3) Direct cellular dmg (eg. alcohol, tobacco, stress, radiation, chemo)
4) Local ischaemia (eg. HTN, vasoconstrictors, stress-induced splanchnic vasocontriction)
5) Chemotherapy → ↓epithelial renewal
6) NSAIDs → ↓PGEs
127
What is the main cause of acute erosive haemorrhagic gastritis?
Ingestion of medications, alcohol
128
What are the 2 macroscopic and 4 microscopic features of acute erosive hemorrhagic gastritis?
Macroscopic:
1) Diffuse hyperemic edematous mucosa
2) Surface erosions
Microscopic:
1) Superficial mucosal defects
2) Fibrinous exudate
3) Neutrophilic infiltrate
4) Corkscrew profiles (tortuosity and mucin depletion → regenerative foveolar hyperplasia)
129
What are 3 pathogeneses of stress-related mucosal injury?
1) HTN, stress-induced splanchnic vasoconstriction → release of vasocontrictors → local ischaemia
2) Intracranial injury → vagal stimulation → gastric acid hypersecretion
3) Systemic acidosis → ↓pH of mucosal cells → ↓acid secretion
130
What are 3 names for different types of stress-related mucosal injury?
1) Stress ulcers: shock, sepsis, trauma
2) Curling ulcers: proximal duodenal ulcers (a/w burns and trauma)
3) Cushing ulcers: gastric, duodenal, esophageal ulcers (a/w brain injury and ↑ intracranial P)
131
What is the macroscopic and microscopic appearance of stress-related mucosal injury?
Macroscopic:
- multiple erosions or ulcers, in the stomach, sharply demarcated, rounded, <1 cm
Microscopic:
- Lack chronic features in PUD such as scarring and blood vessel thickening
132
How does chronic gastritis present clinically?
Less severe than acute but more persistent:
- nausea
- epigastric pain
133
What are 4 causes of chronic gastritis?
1) H. pylori
2) Radiation injury
3) Chronic bile reflux
4) Autoimmune atrophic gastritis
5) Uncommon:
- Eosinophilic, lymphocytic, granulomatous
134
True or false: H. pylori infections of the GIT are typically acquired in childhood present clinically in both acute and chronic infections.
False.
Infection typically acquired in childhood and persists for life without treatment.
Acute infection minimal symptoms, most present with symptoms of chronic gastritis
135
What are 4 virulence factors of H. pylori that aid in causing gastritis?
1) Flagella → motile in viscous mucous
2) Urease → generate ammonia → ↑pH for survival
3) Adhesins → ↑adherence to surface foveolar cells
4) Toxins → eg. CagA
136
What are 3 pathogenesis/sequelae of H. pylori gastritis?
1) Antral inflammation → ↑gastrin → ↑acid → ulcers
2) Chronic infection → atrophic gastritis → ↓parietal cells + intestinal metaplasia → ↓ ulcer risk but ↑adenocarcinoma risk
3) Lymphoid aggregates w germinal centers → MALT → MALT lymphoma
137
What are 2 microscopic features of H. pylori gastritis?
1) Abundant subepithelial plasma cells in superficial LP
2) Lymphoid aggregates w germinal centers
138
What are 4 ways H. pylori gastritis can be diagnosed?
1) Tissue biopsy → rapid urease, culture, PCR
2) Serology for anti-H. pylori Abs
3) Urea breath test
4) Fecal bacteria detection
139
What is the pathogenesis of autoimmune atrophic gastritis?
CD4+ T cells against parietal cell components
→ loss of parietal cells
→ ↓acid and IF production
140
What are 3 sequelae/direct consequences of autoimmune atrophic gastritis?
1) Achlorhydria → hypergastrinemia + G cell hyperplasia → neuroendocrine cell hyperplasia
2) ↓IF → defective ileal B12 abs → pernicious anemia
3) ↓chief cells via gastric gland destruction → ↓serum pepsinogen I
141
How does autoimmune atrophic gastritis typically present?
B12 deficiency:
- megaloblastic anemia
- atrophic glossitis
- malabsorptive diarrhoea
- subacute degeneration of spinal cord
142
Which part of the stomach is spared in autoimmune atrophic gastritis?
Antrum (no parietal cells)
143
What are consequences specific to autoimmune atrophic gastritis?
1) Progression to low-grade neuroendocrine tumours
2) Atrophy and intestinal metaplasia → ↑risk of adenocarcinoma
144
What are the macroscopic features of autoimmune atrophic gastritis?
Body and fundus mucosa appears thinned and rugal folds are lost (atrophic)
145
What are 4 microscopic features of autoimmune atrophic gastritis?
1) Deeper inflammation centered on gastric glands
2) paucity of oxyntic glands
3) intestinal metaplasia (checkerboard pattern)
4) pseudopyloric metaplasia
5) neuroendocrine cell
hyperplasia
146
What is eosinophilic gastritis?
Tissue damage associated with dense infiltrates of eosinophils in the mucosa and muscularis,
usually in the antral/pyloric region
- a/w peripheral eosinophilia and ↑serum IgE l
- Food allergies (e.g. cow’s milk, soy, immune disorders, parasitic infections, H. pylori infections, Crohn’s disease
147
What is lymphocytic gastritis?
Marked increase in intraepithelial T-lymphocytes
- women
- Idiopathic, a/w coeliac disease
148
What is granulomatous gastritis?
Any gastritis that contains granulomas
- Idiopathic, Crohn’s disease, sarcoidosis, infections (mycobacteria, fungi, CMV, H. pylori)
149
What are 4 complications of chronic gastritis?
1) Peptic ulcer disease
2) Mucosal atrophy and metaplasia → ↑adenocarcinoma risk
3) Inflammation and free radical dmg proliferative stimuli → regenerative response to injury + gastrin production (mitogen) → accumulation of genetic alterations → dysplasia
4) Gastritis cystica
150
What is peptic ulcer disease?
Chronic mucosal ulceration in duodenum or stomach that penetrates the muscularis mucosae and deeper
151
What are 4 PUD risk factors?
1) H. pylori infection
2) NSAID (low-dose aspirin synergises with H. pylori for gastric PUD)
3) Cigarette use
4) Cardiovascular disease
5) COPD
6) Illicit drugs (e.g. cocaine reduces mucosal blood flow)
7) Alcoholic cirrhosis (primarily duodenal PUD)
8) Endocrine cell hyperplasia (stimulate parietal cell growth)
9) Zollinger-Ellison syndrome (ulcers also occur in distal duodenum and jejunum)
152
What is the most susceptible site for PUD?
1) Proximal duodenum
2) Lesser curve near the interface of body and antrum
153
What are the macroscopic features of PUD?
Solitary, Round to oval, sharply demarcated, punched-out defect, Usually level with surrounding mucosa
- Variable depth
- Base is smooth and clean
- Scarring and puckering of the wall
154
What are the microscopic features of PUD?
1) Fibrinopurulent/ inflammatory exudate
2) Necrotic debris
3) Granulation tissue
4) Fibrosis
155
What are 4 clinical features of PUD?
1) Epigastric burning or aching pain
- Pain occurs 1-3 hours after food, worse at night, relieved by alkali or food
- Penetrating ulcers can cause referred pain to back, left upper quadrant, chest
2) Nausea and vomiting
3) bloating
4) belching
5) weight loss
156
What are 4 complications of PUD?
1) Bleeding
2) Perforation
3) Obstruction (2° to edema and scarring)
4) Transformation to cancer
157
What are 3 ways PUD is treated?
1) H. pylori eradication
2) Neutralisation of gastric acid with PPI
3) Withdraw offending agents that may interfere with mucosal healing
158
What 3 examples of vascular gastropathies?
1) Gastric antral vascular ectasia (GAVE)
2) Portal hypertensive gastropathy
3) Dieulafoy lesion
159
What are 3 macroscopic features of gastric antral vascular ectasia?
1) Longitudinal stripes of oedematous, erythematous
mucosa that alternated with less severely injured, paler
mucosa
2) “watermelon stomach”
3) Erythematous stripes caused by ectatic mucosal vessels
160
What are 2 microscopic features of gastric antral vascular ectasia?
1) Reactive gastropathy
2) Dilated capillaries containing fibrin thrombi
161
What is portal hypertensive gastropathy?
Portal hypertension secondary to hepatic cirrhosis
162
What is the macroscopic appearance of portal hypertensive gastropathy?
Mosaic pattern, resembling snake skin or cherry-red spots
163
What are 2 microscopic appearance of portal hypertensive gastropathy?
Most prominent in corpus:
1) Reactive gastropathy
2) Congested, dilated mucosal capillaries without fibrin thrombi
164
What is a dieulafoy lesion?
Abnormal caliber-persistent artery in the submucosa
- Most commonly found in the lesser curvature, near the GEJ
- Erosion of mucosa → recurrent bleeding
165
What are 2 hypertrophic gastropathies?
1) Menetrier disease
2) Zollinger-Ellison Syndrome
166
What is Menetrier disease and what are its (i) macroscopic and (ii) microscopic presenations?
Hypertrophic gastropathy due to excessive secretion of TGF-alpha:
i) Macroscopic: Irregular enlargement of gastric rugae in body and fundus, sparing the antrum
ii) Microscopic: Foveolar hyperplasia with focally dilated glands
167
What is Zollinger-Ellison Syndrome and what are its (i) macroscopic and (ii) microscopic presenations?
Gastrin-secreting neuroendocrine tumours (gastrinoma) in small intestine or pancreas; sporadic or MEN1 → duodenal ulcers or chronic diarrhoea:
i) Macroscopic: marked ↑ in oxyntic mucosal thickness
ii) Microscopic: Massive parietal cell hyperplasia, mucous neck and neuroendocrine cell hyperplasia
168
What is the difference between a true and a meckel diverticulum?
Meckel → vestigial remnant of vitelline duct (anti-mesenteric border of ileum)
True → blind outpouching communicating w lumen (all 3 layers of wall)
169
What are 3 congenital pathologies of the intestine?
1) Meckel diverticulum
2) Hirschsprung disease
3) Anorectal atresia
170
How does Meckel diverticulum present clinically (3)?
Most asymptomatic
1) painless rectal bleeding
2) obstruction (intussuception)
3) meckel diverticulitis (clinically similar to acute appendicitis)
171
EXTRA: What is the rule of 2s
Rule of 2s for meckel diverticulum:
- 2% of the population
- Twice as common in males
- Within 2 feet of the ileocecal valve
- 2 inches in length
- 2 types of heterotopic mucosa (pancreas and gastric tissue)
- Presentation before age of 2
172
What is an anorectal atresia?
Congenital anorectal malformation (ARM)
where a normal anal opening is absent at
birth
- Failure of the cloacal diaphragm to involute
- Spectrum of anomalies which can involve
anus alone or also a segment of rectum
173
How does anorectal atresia present clinically (2)?
1) Abdominal distension
2) not passing meconium (baby's first poop!)
- usually recognised @ birth upon visual inspection
174
What is Hirschsprung disease?
Congenital megacolon:
Failure of neural crest-derived ganglion cells to migrate into the distal colon (mutation in the receptor tyrosine kinase RET)
- Distal intestinal segmentlacks both Meissner submucosal plexus and the Auerbach
myenteric plexus (aganglionosis) → Failure of aganglionic segment to relax → absence of coordinated peristalsis →
functional obstruction → proximal dilatation (megacolon)
- Defect always begins at the rectum but extends proximally for variable lengths
175
How does Hirschsprung disease present clinically (3)?
1) Failure to pass meconium
2) Abdominal distension
3) Bilious vomiting
176
What are 3 complications of Hirschsprung disease?
1) Fluid and electrolyte imbalances
2) Perforation
3) Enterocolitis
4) Peritonitis
177
How is Hirschsprung disease diagnosed and treated?
Diagnosed via histology (ganglion cells absent)
Treatment: resection of aganglionic segement
178
What are 4 risk factors for bowel ischaemia?
1) Arterial thrombosis (eg. atherosclerosis)
2) Arterial embolism (eg. aortic athroma)
3) Venous thrombosis
4) Non-occlusive ischaemia (eg. HF, shock, vasoconstrictors)
5) Misc. (eg. radiation, mechanical obstruction)
179
What differentiates the pathogenesis of intestinal mucosal/mural infarction and transmural infarction in ischaemic bowel disease?
Mucosal/Mural: extensive narrowing/occlusion
Transmural: sudden occlusion of main artery
180
What are 5 effects/sequelae of ischaemic bowel disease?
1) F(x)-al obstruction → vomiting, distension
2) Muscle ischaemia → abdominal angina (pain after meals)
3) Mucosal necrosis → exudate and hemorrhage → bloody diarrhoea
4) Muscle necrosis → ↓peristalsis ↓bowel sounds
5) Transmural necrosis → perforation → peritonitis
6) Gram -ve bacteremia → endotoxic shock
181
Why is the colon the most common site for ischaemic bowel disease?
Watershed zones (supplied by terminal branches)
182
What are the macroscopic features of ischaemic bowel disease?
Depends on type but infarcted area: dusky, congested to purple-red
(acute, transmural → sharp demarcation/transition)
183
What are the microscopic features of ischaemic bowel disease (3)?
1) Mucosal change
- atrophy
- hyperproliferative crypts
- fibrous scarring of LP in chronic ischaemia
2) Mural changes
- ulceration
- coagulative necrosis
- serositis (w purulent exudates)
3) bacterial superinfection → pseudomembrane formation
184
How does (i) acute and (ii) chronic ischaemic bowel disease present?
i) Acute:
- sudden onset cramping, abdo pain, hematochezia
- ↓ bowel sounds, guarding, rebound tenderness
- shock
ii) chronic
- Intermittent bloody diarrhoea interspersed with periods of healing
- Rarely, stricture formation
- Mimic inflammatory bowel disease
185
What is pseudomembranous colitis caused by?
Clostridioides difficile
- a/w AB use → disruption normal microbiota → C. diff overgrowth
186
What are 4 risk factors for pseudomembranous colitis?
1) AB use (esp. clindamycin and cephalosporins)
2) Age
3) Hospitalisation
4) Immunosuppression
187
How is pseudomembranous colitis diagnosed and treated?
Diagnosed via histology (C. diff toxin)
Tx: Metronidazole and Vancomycin
188
What are the clinical features (4) and complication of pseudomembranous colitis?
Clinical features:
1) Fever
2) Leukocytosis
3) Abdo pain
4) Watery diarrhoea → dehydration
Complication:
- toxic megacolon
189
What are the (i) macroscopic and (ii) microscopic featuresd of pseudomembranous colitis?
Macroscopic:
- Colon coated with pseudomembranes made up of adherent layer of inflammatory cells/debris
Microscopic:
- Mucopurulent exudate that erupts from damaged crypts to form “volcano” lesions
190
What are 2 ways in such intestinal TB can occur?
1) Primary:
- Ingestion of M. bovis (raw milk)
2) Secondary:
- sputum ingestion from active pulmonary TB
- hematogenous spread from distant focus
- lymphatic spread through infected nodes
- direct extension from contiguous site
191
How does intestinal TB present clinically (5)?
1) Abdo pain
2) Fever
3) Altered bowel habits
4) Obstruction
5) WL
6) Lymphadenopathy
7) Pulmonary involvement → pulmonary symptoms
192
What are the macroscopic (3) and microscopic (1) features of intestinal TB?
Macroscopic:
1) sharply-defined ulcers (circumferential/transverse)
2) inflammatory polyploid masses
3) strictures, bowel wall thickening
Microscopic:
- caseating granulomas
(will stain red w ZN stain)
193
What are the macroscopic (3) and microscopic (1) features of amoebiasis?
Macro:
1) Flask-shaped ulcers
2) Amoeboma (inflammatory mass like tumour)
3) Diffuse colitis
Micro:
- trophozoites w round dense nuclei and ingested RBCs
193
How does intestinal amoebiasis occur?
Entamoeba histolytica
- ingested cyst pass through stomach and colonise colon (have wall R to acid)
- release trophozoites → invade colonic epithelium
193
How does intestinal amoebiasis present clinically (3)?
1) Hematochezia + mucus
2) abdo pain
3) fever (amoebic colitis)
193
What other organ is affected in intestinal amoebiasis?
Liver (form abscess)
- embolise via portal circulation
194
How does acute appendicitis present clinically (5)?
1) Periumbilical pain → localised to right iliac fossa
2) Nausea and vomiting
3) fever
4) Leukocytosis
5) mild neutrophilic leukocytosis
6) McBurney sign
195
What are 3 ddx for acute appendicitis?
1) Mesenteric lymphadenitis
2) Acute salpingitis
3) Ectopic pregnancy
196
What is the pathogenesis of acute appendicitis?
Luminal obstruction
→ ↑ intraluminal P
→ ↓venous outflow, bacterial proliferation, acute inflammation, ischaemia
197
How can acute appendicitis complicate?
Perforation → peritonitis
198
What are the macroscopic (4) and microscopic (2) features of acute appendicitis?
Macro:
1) Edema
2) Turgidity
3) Congestion
4) Hemorrhage
5) Fibrinopurulent exudate
Micro:
1) Neutrophilic infiltration of muscularis propria
2) ulceration
3) Necrosis
199
What is the difference between a true and false diverticulum?
Both outpouching of gut wall
True: all layers of wall (congenital)
False: Mucosa/submucosa only (pulsion: P>wall strength)
200
Diverticulum usually form at weak spots of the gut wall liek where ____________ penetrate.
Vasa recta
201
What are 4 risk factors for diverticular disease?
1) Age
2) Low fibre
3) Low stool volume
4) Reduced activity
202
How does diverticular disease present clinically (3)?
1) Asymptomatic
2) Bleeding → anemia
3) Diverticulitis (pain, fever, leukocytosis)
203
What are 4 complications of diverticular disease?
1) Pericolic abscess, fibrosis, adhesions
2) Colovesical fistula
3) Stricture → obstruction
4) Perforation → peritonitis
204
What are the macroscopic (1) and microscopic (2) features of diverticular disease?
Macro:
- small outpouches in rows betwen taenia coli
Micro:
1) transmural neutrophilic infiltrate
2) Abscess
205
What are 2 forms of inflammatory bowel disease?
1) Crohn's disease
- any part of GIT
- transmural skip lesions
2) Ulcerative colitis
- only colon and rectum
- continuous
- limited to mucosa and submucosa
206
What are 5 factors that contribute to the pathogenesis of inflammatory bowel disease?
1) Genetic predisposition (eg. NOD2 polymorphisms → 10x risk of CD)
2) Environmental
3) Mucosal immune regulation
4) Autophagy and cellular stress response
5) Host-microbial interactions (gut microbiome)
207
How does Crohn's disease present clincally (3)?
Variable, intermittent
1) hematochezia
2) fever
3) Abdo pain
208
What are the macroscopic (5) and microscopic (5) features of crohn's disease?
Macro:
1) Multiple, separate, sharply delineated areas of disease → skip lesions
2) Elongated, serpentine ulcers oriented along the axis of the bowel
3) Ulceration with sparing of interspersed normal mucosa (patchy distribution) → cobblestone mucosa
4) Fissures/fissuring ulcers → fistula, perforation
5) Transmural inflammation, fibrosis → stricture, creeping fat
Micro:
1) Active inflammation - Neutrophilic cryptitis, crypt abscess
2) Chronicity changes – crypt architectural distortion, epithelial metaplasia (pseudopyloric metaplasia, Paneth cell metaplasia in left colon)
3) Patchy distribution of inflammatory changes
4) Transmural chronic inflammation with lymphoid follicles
5) Non-caseating granulomas in any layer of intestinal wall, draining mesenteric lymph nodes
209
What are 6 extraintestinal manifestations of crohn's disease?
1) Uveitis
2) Migratory polyarthritis
3) Sacroileitis
4) Ankylosing spondylitis
5) Erythema nodosum
6) Cutaneous granulomas
7) Finger clubbing
8) Pericholangitis and primary sclerosing cholangitis (more common in UC)
210
Crohn's disease and ulcerative colitis both cause and increase risk of _____________________ in long-standing disease.
Colonic adenocarcinoma
211
How does ulcerative colitis present clinically (2)?
1) Relapsing attacks of bloody diarrhoea with stringy mucoid material
2) abdo pain, cramps that are temporarily relieved by defaecation
212
What are the macroscopic (5) and microscopic (5) features of ulcerative colitis?
Macro:
1) Red, granular mucosa
2) Broad-based ulcers, aligned along long axis of colon
3) Isolated islands of regenerating mucosa bulge into lumen to form pseudopolyps, which may fuse to form mucosal bridges
4) Mucosal atrophy
5) NOT transmural - colon wall is not thickened, serosal surface normal, strictures do not occur
Micro:
1) Active inflammation - Neutrophilic cryptitis, crypt abscess
2) Chronicity changes – crypt architectural distortion, epithelial metaplasia (pseudopyloric metaplasia, Paneth cell metaplasia in left colon)
3) Diffuse distribution of inflammatory changes
4) Inflammation mostly limited to the mucosa and submucosa
5) Granulomas NOT present
213
What are 6 extraintestinal manifestations of ulcerative colitis?
1) Uveitis
2) Migratory polyarthritis
3) Sacroileitis
4) Ankylosing spondylitis
5) Erythema nodosum
6) Pericholangitis and primary sclerosing cholangitis (more common in UC)
214
How does intestinal obstruction present clinically (3)?
1) Abdo pain
2) distention
3) vomiting
4) constipation
215
Intestinal obstruction:
________________ most often involved due to narrow lumen
80%: (4)
20%: (3)
Small bowel most often involved due to narrow lumen
80%: Hernia, adhesion, volvulus, intussusception
20%: Tumours, infarctions, strictures
216
How does adhesion lead to intestinal obstruction?
Surgical procedures, infection or other causes of peritoneal inflammation
→ fibrous adhesions between bowel segments, abdominal wall, or operative sites
→closed loop → internal herniation
217
How does volvulus lead to intestinal obstruction?
loop of bowel twists about its mesenteric point of attachment
→ luminal and vascular compromise
218
How does intussusception lead to intestinal obstruction?
segment of intestine, constricted by a wave of peristalsis, telescopes into the immediate distal segment
219
What are 2 complications of hernias?
1) Pressure at the neck of the hernia impairs venous drainage → stasis and oedema → ↑ in bulk of herniated loop → permanent entrapment ‘incarceration’ → arterial and venous compromise → ‘strangulation’ and infarction
2) Constriction of bowel lumen produces IO
