Skin Pathology (Pigmented and Infectious Lesions) Flashcards
(46 cards)
1
Q
What is Seborrheic Keratosis?
A
- benign proliferation of squamous cells
- common in the elderly.
- presents as raised, discolored plaques on the extremities or face; often has a coin-like, waxy, ‘stuck-on’ appearance.
2
Q
What characterizes seborrheic keratosis on histology?
A
- keratin PSEUDOCYSTS
3
Q
** What is Leser-Trelat sign?
A
- SUDDEN ONSET of multiple seborrheic keratoses and suggests underlying carcinoma of the GI tract
4
Q
What is Acanthosis Nigricans?
A
- epidermal hyperplasia with darkening of the skin (VELVET-LIKE skin).
- often involves the axilla or groin.
5
Q
With what is acathosis nigricans associated?
A
- insulin resistance (T2DM) or malignancy (especially gastric carcinoma).
6
Q
*** What is Basal Cell Carcinoma?
A
- malignant proliferation of the basal cells of the epidermis.
- MOST COMMON CUTANEOUS malignancy.
7
Q
What are the risk factors for basal cell carcinoma?
A
- UBV-induced DNA damage (prolonged exposure to sunlight, albinism, and xeroderma pigmentosum).
8
Q
*** How does basal cell carcinoma present?
A
- elevated nodule with a central, ulcerated crater surrounded by dilated (TELANGIECTATIC) vessels (PINK-PEARL-LIKE papule).
- classic location is UPPER LIP
9
Q
What will you see on histology with basal cell carcinoma?
A
- nodules of basal cells with peripheral palisading (cells are lining up against some space).
10
Q
How do you treat basal cell carcinoma?
A
- excision
* metastasis is rare and has excellent prognosis :)
11
Q
*** What is Squamous Cell Carcinoma?
A
- malignant proliferation of squamous cells characterized by formation of KERATIN PEARLS.
12
Q
What are the risk factors for squamous cell carcinoma?
A
- same as basal cell carcinoma: UVB-induced DNA damage from prolonged exposure to sunlight, albinism, and xeroderma pigmentosum.
- ALSO: immunosuppressive therapy, ARSENIC POISONING, and chronic inflammation (ex. scar from burn or draining sinus tract).
13
Q
*** How does squamous cell carcinoma present?
A
- ulcerated, nodular mass, usually on the face (classically involving the LOWER LIP).
14
Q
How do you treat squamous cell carcinoma?
A
- excision
* metastasis is uncommon and has an excellent prognosis :)
15
Q
What is Actinic Keratosis?
A
- a PRECURSOR lesion of squamous cell carcinoma and presents as a hyperkeratotic, scaly plaque, often on the face, back, or neck.
- may look like a little horn.
16
Q
What is Keratoacanthoma?
A
- well-differentiated squamous cell carcinoma that develops RAPIDLY and REGRESSES spontaneously.
- presents as a CUP-SHAPED TUMOR filled with keratin debris.
17
Q
What are the melanocytes?
A
- responsible for skin pigmentation using TYROSINE to make MELANIN in the MELANOSOMES, which are passed off to the keratinocytes, resulting in skin pigmentation.
- present in basal layer of epidermis and derived from NEURAL CREST.
18
Q
What is Vitiligo?
A
- LOCALIZED LOSS of skin pigmentation due to AUTOIMMUNE destruction of melanocytes.
19
Q
What is Albinism?
A
- CONGENITAL lack of pigmentation due to enzyme defect (TYROSINASE) that impairs melanin production.
- may involve eyes (ocular form) or both eyes and skin (oculocutaneous form).
- increased risk for skin cancer (basal cell, squamous cell, or melanoma) due to reduced protection against UVB.
20
Q
What is a Freckle?
A
- small, tan to brown macule due to increased number of MELANOSOMES (melanocytes are NOT increased).
- darkens when exposed to sunlight.
- Lentigo is similar to a freckle, but does NOT darken when exposed to the sun.
21
Q
What is Melasma?
A
- mask-like hyperpigmentation of the cheeks.
* associated with pregnancy and oral contraceptives.
22
Q
What is a Nevus (mole)?
A
- benign neoplasm of melanocytes.
- CONGENTIAL nevus is present at birth; often larger and associated with HAIR= good sign :)
23
Q
What is an Acquired Nevus?
A
arises later in life:
- begins as nests of melanocytes at the dermal-epidermal junction (JUNCTIONAL nevus); most common mole in CHILDREN.
- grows by extension into the dermis (compound nevus).
- junctional component is eventually lost, resulting in an INTRADERMAL nevus, which is the most common mole in ADULTS.
24
Q
Can dysplasia arise in a nevus, leading to melanoma?
A
YES
25
**** What is Melanoma?
- malignant neoplasm of melanocytes; MOST COMMON cause of DEATH from skin cancer.
26
*** What are the risk factors for melanoma?
exposure to UVB:
- prolonged exposure to sunlight
- albinism
- xeroderma pigmentosum
* additionally DYSPLASTIC NEVUS SYNDROME= autosomal dominant disorder (CDKN2 and CDKN4) characterized by formation of dysplastic nevi (flat macules, slightly raised plaques with pebbly surface, or target like lesions with a darker raised center and irregular flat periphery).
27
*** How do we distinguish melanoma from a nevus (mole)?
- Asymmetry
- Borders are irregular
- Color is not uniform
- Diameter greater than 6 mm
28
What are the 2 growth phases of melanoma?
1. RADIAL growth= horizontally along the epidermis and superficial dermis; LOW RISK of metastasis.
2. VERTICAL growth= into the deep dermis; increased risk of metastasis.
29
What is the most important prognostic factor in predicting melanoma metastasis?
- DEPTH of extension (BRESLOW THICKNESS)
30
What are the 4 major subtypes of melanoma?
1. Superficial spreading= MOST COMMON and dominant early radial growth :)
2. Lentigo maligna melanoma= radial growth :)
3. Nodular= early vertical growth :(
4. Acral lentiginous= arises on PALMS and SOLES, often in dark-skinned individuals; not related to UV light.
31
What is Impetigo?
- superficial bacterial skin infection (usually Staph aureus or Strep pyogenes) usually in CHILDREN.
- presents as erythematous macules (flat lesion) that progresses to pustules, usually on the face.
- rupture of pustules results in erosions and dry, crusted, honey-colored serum.
32
What is Cellulitis?
- DEEPER (dermal and subcutaneous) infection (usually Staph aureus or Strep pyogenes).
- presents as a red, tender, swollen rash with FEVER.
33
What are the risk factors for cellulitis?
- recent surgery, trauma, or insect bite.
34
To what can cellulitis progress?
- NECROTIZING FASCIITIS= necrosis of SUBcutaneous tissue due to infection with anaerobic 'flesh-eating' bacteria, which produce CO2 leading to crepitus.
* SURGICAL EMERGENCY.
35
What is Staphylococcal Scalded Skin Syndrome?
- sloughing of skin with erythematous rash and FEVER due to Staph aureus infection; exfoliative A and B TOXINS result in epidermolysis of teh stratum GRANULOSUM.
- leads to significant skin loss
36
*** How do you distinguish staphylococcal scalded skin syndrome from toxic epidermal necrolysis (TEN)?
- by level of skin separation; TEN occurs at the dermal-epidermal junction.
37
What is a Verruca (wart)?
- flesh-colored papules (raised lesion) with a rough surface.
- due to HPV infection of keratinocytes; characterized by koilocytic change.
- HANDS and FEET are common locations.
38
What is Mulluscum Contagiosum?
- firm, pink umbiliciated papules due to POXVIRUS.
| - most often arises in CHILDREN, but also can occur in SEXUALLY ACTIVE adults and immunocompromised individuals.
39
What will you see on histology with mulluscum contagiosum?
- keratinocytes with viral cytoplasmic inclusions (mulluscum bodies).
40
What protective mechanism prevents progression to melanoma in malanocytic nevi?
- accumulation of p16/INK4a, which inhibits cyclin-dependent kinases, arresting cell growth :)
* this is disrupted however in melanoma :(
41
What characterizes a Blue Nevus?
- spindle shaped cells and heavy pigmentation.
42
What is a Spitz Nevus?
- usually occurs before puberty as a raised, pink or red nodule in the skin of the face.
- SPINDLE (cigar shaped cells) or EPITHELIOID (polygonal shape with eosinophilic cytoplasm).
43
What is a Halo Nevus?
- melanocytic nevus surrounded by a zone of depigmented skin.
- usually on trunk of young people.
- heavy infiltration of lymphocytes.
44
Does a malignant melanoma tend to have a better or worse prognosis if it is found on the back or chest?
- WORSE than when found on the extremities.
| * lymphocytic infiltrate indicates worse prognosis.
45
What special stains can we use to identify malignant melanoma?
- S-100
| - HMB-45 (more specific)
46
What is the most common primary intraocular malignancy in adults?
- Ocular melanoma (spindle vs epithelioid types). Epithelioid has worse prognosis.
* spreads hematogenously to liver.
