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Flashcards in Respiratory1 Deck (100):
1

What is the cell indicated by the arrows? What do these cells produce?

Q image thumb

Type II pneumocytes.

These cells produce surfactant

2

Describe the type II pneumocyte appearance.

These are cuboidal-like cells with round nuclei and washed out, faomy cytoplasm. The cytoplasmic appearance is due to the lipid content

3

What structure in the type II pneumocytes contain the surfactant?

Lamellar bodies (secretory granules)

4

Who is at risk for aspiration pneumonia?

Patients with a depressed cough reflex and depressed consciousness, i.e., alcoholics, comatose patients

Also: seizure disorders, dementia, elderly

5

What organisms commonly cause aspiration pneumonia?

anaerobic bacteria of the oropharynx: fusobacterium, peptococcus, bacteroides

6

What is the classic (gross) result of aspiration pneumonia?

A right lower lobe abcess

7

Why are abcesses that are found in aspiration pneumonia typically found in the right lower lobe (as opposed to the left, for instance)?

The right main stem bronchus branches at a less acute angle than the left

8

A 30-yo man is brought to the emergency department after sustaining a severe head injury from an epileptic seizure. He is unresponsive on arrival and is intubated. Five days after admission to the intensive care unit, he develops a spiking fever. Chest x-ray shows a cavitary lesion in the right lung with an air-fluid level and surrounding consolidation. Lung culture reveal growth of fusobacterium and bacteroides species. The patient dies one week later, and autopsy reveals an abcess in the right lower lung. What is the underlying cause of the lung lesion?

Aspiration pneumonia

Key points:

(1) bacterial culture--anaerobic (fusobacterium and bacteroides)                                                                    (2) diminished cough reflex and consciousness         (3) cavitary lesion/right lower lobe abscess

9

What is the characteristic description of the lesion found on x-ray for an abcess due to aspiration pneumonia?

A cavitary lesion with an air-fluid level

10

What is the composition of surfactant?

lipids, protein, lecithin (carbohydrates)

11

What is the consequence of reduced/insufficient surfactant?

Surfactant reduces the surface tension in the alveoli, preventing the alveoli from collapsing when a person exhales. If there is insufficient surfactant, the alveoli will collapse when exhaling (atalectasis), and the compliance of the lung will be reduced (it will be harder--take more force--to expand the lung on inspiration.

12

Factors that increase surfactant production

(1) (cortico)steroids

(2)thyroxine works in synergy with corticosteroids

(3) Active labor increases synthesis

(4) intrauterine stress increases corticosteroid release

13

Factors that decrease surfactant production

(1) maternal diabetes

(2) C-section prior to active labor

(3) mutations in surfactant protein A or B genes (SP-A or SP-B genes)

14

How might mitral obstruction affect pulmonary compliance?
 

Mitral obstruction, and other conditions that promote pulmonary edema, can decrease pulmonary compliance.

15

What is the most common cause of epiglottitis in patients who *are* immunized against H. influenza?

Streptococcus pneumoniae

16

What is the most common cause of epiglottitis?

Haemophilus influenza

17

What would be the relative values of PaO2, O2 content, and [Hb] in a patient with anemia?

(Normal, increased, decreased)

PaO2 will be normal

[Hb] will be reduced

O2 content will be reduced, proportional to the decrease in Hb

18

What is the normal average Hb concentration?

15g/dL

19

How many grams of oxygen can 1 gram of Hb carry?

1.34

20

What compensatory changes in cardiac output would accompany anemia?

Anemia is a reduction in RBC mass, which means that the [Hb] will be decreased, as will be the O2-content of the blood. The body will try to compensate for the decreased O2-carrying capacity by increasing CO in order to maintain O2 delivery to the tissues. This will be achieved by increasing both SV and HR

21

A 62-yo woman comes to the physician because of worsening fatigue. She has lost 7 lbs in the past two months with no change in her appetite. Laboratory studies show her Hb is 6.8 g/dL. Her stool is guaiac-positive. Colonoscopy shows a large fungating mass in her ascending colon. Which of the following is most likely to be decreased in this woman?

(a) arterial O2 content (b) arterial O2 saturation (c) arterial PO2 (d) cardiac output (e) HR (f) stroke volume

arterial O2 content

a decrease in the hemoglobin [  ] of the blood will cause a proportional decrease in the O2-carrying capacity

22

A 62-yo woman comes to the physician because of worsening fatigue. She has lost 7 lbs in the past two months with no change in her appetite. Laboratory studies show her Hb is 6.8 g/dL. Her stool is guaiac-positive. Colonoscopy shows a large fungating mass in her ascending colon. Which of the following is most likely to be increased in this woman?

(a) arterial O2 content (b) arterial O2 saturation (c) arterial PO2 (d) cardiac output (e) HR (f) stroke volume

cardiac output, stroke volume and HR

these are compensatiry changes the body makes in response to the anemia to maintain oxygen delivery to the tissues

23

A 62-yo woman comes to the physician because of worsening fatigue. She has lost 7 lbs in the past two months with no change in her appetite. Laboratory studies show her Hb is 6.8 g/dL. Her stool is guaiac-positive. Colonoscopy shows a large fungating mass in her ascending colon. How are arterial O2 saturation and pressure likely to be affected?

 

Both PaO2 and O2 saturation are virtually unaffected by hemoglobin concentration, and would be normal in this patient

24

A 3 year old boy is brought to the ED by his parents because he inhaled a peanut. Physical exam shows cyanotic extremities and lips. Bronchoscopy shows a peanut lodged in the _______, largely occluding it. Peripheral O2 saturation is 65%. Where is the peanut most likely lodged and why?

 

The peanut is most likely lodged in the right mainstem bronchus, because it branches at a less acute angle than the left.

 

25

A 3 year old boy is brought to the ED by his parents because he inhaled a peanut. Physical exam shows cyanotic extremities and lips. Bronchoscopy shows a peanut lodged in the right mainstem bronchus, largely occluding it. Peripheral O2 saturation is 65%. Which of the following best explains these findings? 

(a) decreased PO2 in inspired air

(b) decreased pulmonary diffusion capacity

(c) hypoventilation of central origin

(d) hypoventilation of peripheral origin

(e) inequalities of ventilation and perfusion

Inequalities of ventilation and perfusion (V/Q mismatch)--in this case, blood is going to both lungs (perfusion), but air is prevented from entering one of the lungs (ventilation). This leads to hypoxemia.

26

With what genetic mutation is small cell carcinoma associated?

L-myc

27

From where are the tumor cells of a small cell carcinoma derived?

bronchial neuroendocrine cells

28

Describe the gross appearance and histology of a small cell carcinoma

gross appearance: grey-tan-white

histology: uniform, small, blue cells with little cytoplasm that resemble lymphocytes in their appearance

The cells contian neurosecretory granules in their cytoplasm and will be chromogranin positive. (small cell carcinoma is derived from neuroendocrine cells)

29

What is the typical location of a small cell carcinoma?

Located centrally, along the bronchial airways

30

What lung carcinoma is associated with SIADH and Cushing syndrome?

small cell carcinoma

31

With what co-morbidities is small cell carcinoma associated?

Paraneoplastic syndromes, including SIADH, Cushing syndrom, and Eaton-Lambert syndrome.

The tumor cells can ectopically produce ADH (leading to SIADH), as well as ACTH (leading to Cushing syndrome)

32

A 52 yo woman is brought to the ED after a seizure. SHe has no history of head trauma. Her husband states that she has been coughing a lot more in the past year with occasional blood-tinged sputum. She has smoked 1 pack of cigarettes a day for the past 30 years. Labs show a serum sodium of 128 mEq/L. The urine osmolarity is higher than the serum osmolarity. MRI of the head is unremarkable. Which of the following is the most likely cause of these findings? Why?

(a) adenocarcinoma

(b) squamous cell carcinoma

(c) carcinoid tumor

(d) small cell carcinoma

(e) colon carcinoma

small cell carcinoma

The hyonatremia and urine osmolarity that is higher than the serum osmolarity are indicative of SIADH (ectopic ADH secretion). This paraneoplastic syndrome is associated with small cell carcinoma

33

A 52 yo woman is brought to the ED after a seizure. SHe has no history of head trauma. Her husband states that she has been coughing a lot more in the past year with occasional blood-tinged sputum. She has smoked 1 pack of cigarettes a day for the past 30 years. Labs show a serum sodium of 128 mEq/L. The urine osmolarity is higher than the serum osmolarity. MRI of the head is unremarkable. Which of the following is the most likely cause of these findings? What may account for this patient's seizures?

(a) adenocarcinoma

(b) squamous cell carcinoma

(c) carcinoid tumor

(d) small cell carcinoma

(e) colon carcinoma

This patient has small cell carcinoma, which is ectopically producing ADH, leading to SIADH.

The hyponaturemia that results from SIADH is leading to seizure activity.

34

With which of the following tumors might you also observe urinary tract calcium stones? Why?

(a) adenocarcinoma

(b) squamous cell carcinoma

(c) carcinoid tumor

(d) small cell carcinoma

(e) colon carcinoma

Squamous cell carcinoma

squamous cell carcinoma can secrete parathryoid hormone-related peptide (PTHrP), which can mimic hyperparathyroidism and lead to hypercalcemia. This can lead to renal calcium stones.

35

With which of the following tumors might present with pneumonia-like consolidation on imaging?

(a) adenocarcinoma

(b) squamous cell carcinoma

(c) carcinoid tumor

(d) small cell carcinoma

(e) bronchioalveolar carcinoma

bronchioalveolar carcinoma

36

Let's say there is a large exophytic tumor in the ascending colon (i.e., colon carcinoma) that metastasizes to the lung. Where would the metastases generally be located?

These metastatic tumors tend to be located peripherally and involve multiple lesions.

37

What would electron microscopy reveal in a small cell carcinoma?

intracytoplasmic (neuro)secrectoy granules

38

What lung carcinoma is associated with serotonin secretion?

Carcinoid tumor

39

What is the forced vital capacity of patient X and patient Y

Q image thumb

Patient X: 5L

Patient Y: 3L

40

What is the FEV1 for patient X and patient Y?

Q image thumb

Patient X: 4L

Patient Y: 1.5L

41

What is the FEV1/FVC for patient Y? Given that trace X was derived from a person with healthy lungs, which of the following conditions is likely represented by trace Y?

(a) asbestosis

(b) emphysema

(c) pleural effusion

(d) pneumothorax

(e) silicosis

Q image thumb

FEV1/FVC = 1.5/3 = 0.5

Trace Y shows a reduction in FEV1, FVC, and the FEV1/FVC ratio. This curve represents an obstructive lung disease, and therefore likely represents emphysema

42

How would the FEV1/FVC ratio be affected in a patient with a pleural effusion or pneumothorax?

FEV1/FVC is a measure of airway resistance. An increase in airway resistance will lead to a decrease in the FEV1/FVC ratio, as seen in obstructive diseases like emphysema. Although the FVC will be reduced in these conditions, airway resistance is not usually greatly affected, so the FEV1/FVC ratio may be normal.

43

An elevated PaO2 and low PaCO2 is generally indicative of what?

higher than normal ventilation

44

How might the PaO2 and PaCO2 be affected in a person with restrictive lung disease?

The blood gases in a person with restrictive lung disease may be normal. In a person with advanced restrictive disease, they may have reduced arterial oxygen and increased carbon dioxide because of low ventilation

45

How does anatomic dead space change at different lung inflations?

It remains relatively constant

46

How does pulmonary compliance change in a person with restrictive lung disease?

compliance decreases due to increased elastic recoil.

47

What is the association with chronic right-sided heart failure and the liver?

chronic right-sided heart failure can result in passive congestion of the liver, which is associated with a characteristic nutmeg appearance on cut surface.

48

What diagnosis should you suspect in a "pink puffer" with dyspnea, increased chest diameter, smoking history and minimal hypoxemia on blood gas analysis?

Emphysema

49

How does the maximum expiratory flow rate in obstructive lung disease compare with that in a normal individual?

The maximum expiratory flow rate is decreased for any given lung volume in a patient with obstructive disease because the airway diameter is reduced (and the resistance to air flow is therefore increased).

50

What happens to (forced) vital capaicty in a patient with obstructive lung disease.

(F)VC is reduced in a patient with obstructive lung disease. This is because even though the TLC is increased, so is the RV, causing the difference between them--the vital capacity--to be reduced.

51

Is a pleural effusion an obstructive or a restictive type of lung disease?

Restrictive. This can almost be thought of as synonymous to a chest wall deformity--the patient will have a harder time breathing in, as the effusion creates an inward pressure that reduces the volume of the lung.

52

What would be the predominant cause of hyposxia in a patient with lobar pneumonia?

perfusion/ventilation mismatch.

Blood flow will be increased to the inflammed lung at the same time that airflow to the lung will be obstructed (due to consolidation). This will cause a significant mismatch in perfusion and ventilation.

53

An 80-yo woman from a nursing home is admitted to the hosptial because of respiratory distress. Portable chest x-ray shows right middle and lower lobe infiltrates. Gram stain of the sputum shows large numbers of lancet-shaped, gram positive diplococci. Arterial blood gases show a PO2 of 50 mmHg. What is the most likely disease-causing organism.

streptococcus pneumoniae

The gram stain is classic for this bug. S. pneumoniae is also the most common cause of community-acquired pneumonia, usually seen in middle-aged adults and the elderly.

54

What is the most common cause of lobar pneumonia in adults?

streptococcus pneumoniae

55

By what name is streptococcus pneumoniae also known as?

pneumococcus

56

What type of pneumonia would haemophilus influenza and kelbsiella cause in immunocompetent individuals? How would it appear on imaging?

bronchopneumonia

this pneumonia is consolidation that runs along airways and would be distributed in a patchy manner, often multilobar and bilateral

57

The alveolar wall destruction in emphysema is due to the action of what enzyme? Where does this enzyme come from?

Elastase from neutrophils

58

What are the two types of emphysema? In which case is each seen?

centriacinar -- smoking

panacinar -- alpha-1-antitrypsin deficiency

59

Destruction of alveolar septae around the bronchioles with alveolar air space enlargement accompanied by heavy pigment deposition (anthracosis) is characteristic of what disease process?

emphysema

60

Increased Reid index.

Associated disease?

chronic bronchitis

61

Apical cavitary lesions.

Associated disease?

tuberculosis

62

Curschmann spirals

Associated disease?

asthma

63

Elevated sweat salt levels

Associated disease?

cystic fibrosis

64

Enlarged hilar glands

Associated disease?

granulomatous disease, lymphoma, or tumor

65

What are Curschmann spirals?

These are mucus casts of small airways that are found in asthma patients

66

A 51 yo male smoker comes to the physician because of a fever and a cough productive of greenish-yellow sputum. He has had progressive morning cough with mucus production for the past 5 years. What is the likely diagnosis? What is the cause of the sputum in this patient?

This patient likely has chronic bronchitis, given the years-long history of cough + mucus production.

Patient with chronic bronchitis have an increased risk for infection. The fever and greenish-yellow sputum are likely related to acute infection.

67

A 63 yo man with COPD, end-stage liver disease, and frequent hospitalizations for hepatic encephalopathy comes to the physician b/c of fevers, nights sweats, and cough frequently tinged with blood. The cough has persisted for the last 2 weeks. He smokes 1-2 packs of cigarettes/day for 40 yrs. A CXR shows a complex cavitary lesion in the right upper lobe. Bronchoscopy shows a large lung abscess from which pure Fusobacterium nucleatum is cultured. What is the likely cause of the abscess? What predisposes him to this disease process?

He likely has aspiration pneumonia, espcially given the culture of Fusobacterium, and an abscess in the right lobe.

Aspiration pneumonia typically occurs in patients with a depressed cough reflex and decreased consciousness. This patient has a history of hepatic encephalopathy, which causes impaired cognitive status and a method for aspiration.

68

A 45 yo man with a history of alcohol abuse is brought to the ED by a neighbor b/c of a low-grade fever, chills, weight loss, and a productive cough with red to rust-colored sputum. He has had these symptoms for a little over a week. Egophony is heard on auscultation of the chest, and a CXR shows a cavity in the right lower lobe with an air-fluid level. What is the likely diagnosis? What are the characteristic factors that point to this diagnosis?

aspiration pneumonia with anaerobic normal oral flora

alcohol abuse = decreased consciousness and risk for aspiration

cavity with air-fluid level in the right lower lobe is an abscess that is classically seen in aspiration pneumonia--the right mainstem bronchus branches at a less acute angle than the left.

Symptoms for over a week--symptoms of aspiration pneumonia typically develop over days to weeks

69

What is the mechanism behind aspirin-induced asthama?

Aspirin inhibits the cyclooxygenase pathway w/o affecting the lipoxygenase pathway. This leads to a decrease in the ratio of prostaglandins (bronchodilators) to leukotrienes (bronchoconstrictors). The disrupted balance of these to arachadonic acid metabolites leads to bronchoconstriction in predisposed individuals.

70

What is the mechanism by which viral infections lead to bronchospasm/asthma?

Enhanced vagal stimulation.

viral infections of the upper respiratory tract appear to lower the threshold of the respiratory mucosa to parasympathetic (vagal) stimulation. 

vagal stimulation exerts a bronchoconstrictor effect on the lungs

71

Mechanism by which allergy causes asthma.

Initial exposure to an allergen leads to T cell activation that instruct B cells to produce IgE against the allergen. Re-exposure to the allergen --> cross liking of surface IgE on mast cells --> mast cell degranulation. Mediators released from mast cells (histamine, leukotrienes) cause branchospasm.

**This is a type I hypersensitivity**

72

Occupational asthma (inhalation of chemicals, for example) is mediated by what pathogenic mechanism?

(For instance, atopic asthma is mediated by type I hypersensitivity, and aspirin-induced asthma is mediated by inhibition of cyclooxygenase pathway)

Direct release of bronchoconstrictor substances

73

What are normal arterial levels of PaO2, PaCO2, pH, and HCO3-?

pH: 7.35 - 7.45

PaO2: 80-100

PaCO2: 35-45

HCO3-: 22-26

74

Caseating granulomas with positive acid-fast staining bacilli. Diagnosis?

mycobacterium tuberculosis

75

Autopsy of a 23 yo man who died in a motor vehicle collision shows a small cluster of caseating granulomas in the middle lobe of the right lung, and similar granulomas in the hilar lymph nodes. Acid-fast stainging shows acid-fast bacilli within these lesions. No other lesions are found in the remaining organs and tissues. Which of the following is the most accurate interpretation of these findings?

(a) disseminated infection

(b) primary infection

(c) reactivational disease

(d) re-exposure disease

(e) remote healed infection

Primary infection

primary infection of TB is generally asymptomatic and most frequently located in the lung parenchyma and hilar lymph nodes

76

Mycobacterium avium-intracellulare

Unusual mycobacterial infections that are noted for causing pulmonary and disseminated infections in AIDS patients. These infections are less prevalent than M tuberculosis, except when the CD4+ count is less than 50/uL.

77

What are hemosiderin-laden macrophages on alveolar lavage indicative of? When is it most often seen?

These are indicative of blood leaking into the alveolar space. This is most often seen in congestive heart failure, and these cells are often called heart failure cells.

 

78

Why do we see hemosiderin-laden macrophages in the lungs of patients with congestive heart failure?

These macrophages are indicative of blood that has leaked into the alveoli. Congestive heart failure causes increased pulmonary capillary pressure, which leads to tiny hemorrhages where fluid and RBCs leak into the alveolar space. The pulmonary macrophages then phagocytose the erythrocytes and convert the iron from hemoglobin into hemosiderin

79

What are Light's Criteria for an exudative effusion?

One or more of the following:

(1) pleural fluid protein/serum protein >0.5

(2) pleural fluid LDH/serum LDH >0.6

(3) pleural fluid LDH >2/3 the normal upper limit for serum

80

What is exudative effusion and what is its physiologic cause?

Exudate results from the leakage of protein rich fluid from the plasma into the interstitium. It is usually due to increased vascular permeability caused by inflammation.

(Characterized by protein rich fluid + inflammatory cells)

81

What inflammatory cells would we see in an exudative effusion caused by bacteria (pyogenic organisms)?

neutrophils

82

What inflammatory cells would we see in the exudative effusion caused by a mycobacterial infection or neoplastic infiltration?

chronic inflammatory cells:

macrophages and lymphocytes

83

What is transudate/what is the physiological cause of a transudative effusion?

Transudate results from either an increase in hydrostatic pressure or decreased in oncotic pressure of the blood vessel. 

Transudate contains less protein than exudate and few (if any) inflammatory cells.

84

What are the causes of transudative effusions?

Decreased oncotic pressure: cirrhosis, nephrotic syndrome, protein-losing enteropathy

Increased hydrostatic pressure: congestive heart failure.

85

A 27 yo primigravid woman has been seen regularly for prenatal care and has had an uneventful pregnancy. At 28 weeks' gestation, she complains of a malodorous vaginal discharge, bacterial vaginosis is diagnosed and she is treated with antibiotics. At 30 weeks' gestation, she goes into labor, and despite the use of tocolytics, she delivers the next day. The neonate develops tachycardia, nasal flaring, and grunting, and requires intubation. Which if the following is most likely decreaed in the alveoli of this newborn?

(a) a-ketoglutarate

(b) arachadonic acid

(c) choline

(d) corticosteroids

(e) phenylalanine

Choline

The main lipid component of surfactant is phosphatidylcholine (lecithin)

Note: corticosteroid levels are not insufficient in the alveoli. RDS b/c of prematurity is due to insufficient surfactant production. Corticosteroids do, however, promote production/secretion of surfactant

86

How does CHF lead to a pleural effusion?

increased hydrostatic pressure in pulmonary capillaries

CHF --> back up of blood flow in pulmonary capillaries --> increased hydrostatic pressure in pulmonary capillaries --> movement of fluid  into alveolar spaces and pleural cavity

87

How does nephrotic syndrome lead to a pleural effusion?

Decreased oncotic pressure

in nephrotic syndrome, there is a loss of albumin --> decrease in oncotic pressure --> fluid movement into alveolar spaces and pleural cavity

88

How will the pleural fluid appear on thoracentesis from a pleural effusion due to CHF or nephrotic syndrome?

Clear yellow, resembling serum.

Both of these conditions would lead to a transudative effusion

89

What is the difference in appearance of pleural fluid between that caused by bacteria (pyogenic infection), and that due to a chylothorax?

In a chylothorax, the pleural fluid will appear milky-white and separate upon standing (due to chylomicron-rich [lipid rich] lymphatic fluid)

In a pyogenic infection, the pleaural fluid will have a yellow-green appearance.

90

What are the causes of a chylous pleural effusion (chylothorax)?

Damage to the thoracic duct that allows the chylomicron-rich lymphatic fluid to drain into the pleural cavity.

This damage can be caused by a tumor or traume (e.g., knife stabbing)

91

A premature infant with respiratory distress and a biopsy showing surfactant-rich exudate and silver-staining cysts. Diagnosis?

Pneumocystis jiroveci pneumonia

92

In what two groups does Pneumocystic jirovci cause pneumonia?

infants and patients with AIDS

(both groups are immunocompromised)

93

Pathophysiologically, how does pneumocystic jiroveci cause pneumonia in immunocompromised patients?

It causes atypical pneumonia due to the over-replication of type II pneumocytes, and their production of surfactant-rich exudates. These fill the alveolar sacs and eventually cause death by asphyxiation.

94

How does pneumocystis jiroveci appear ongram stain?

As silver-staining cyts (spherical bodies with sharply outlined walls)

95

gross/histology of asthma

--copious mucus plugs

--numerous bronchiol eosinophils and neutrophils

--thickening of broncial basement MB

--hypertrophy of bronchial smooth muscle and mucus glands

96

What are Charcot-Leyden crystals? With what condition are they associated?

They are intra-alveolar rhomboid structures derived from enzymes present within eosinophils. 

Assoicated with asthma

97

Is it possible to see noncaseating granulomas in a mycobacterium tuberculosis infection?

Yes. In an immunocompromised individual (e.g., patient with AIDS), primary infection may show noncaseating granulomas. This is due to the decifient T cell response.

98

A 55 yo woman comes to the emergency department b/c of dyspnea and persistent, nonproductive cough for the past 6 weeks. She has smoked 1-2 packs of cigarettes daily for 20 years. Physical exam shows obesity, a rounded face, and hypertension. A CXR shows a 3-cm mass in the upper lobe of the right lung. A CT-guided biopsy specimen of the mass shows sheets of undifferentiated cells with a high nuclear-cytoplasmic ratio and nuclear hyperchromasia. What is the most likely diagnosis? Why?

small cell carcinoma

--30 pack-year hx of smoking

--sheets of undifferentiated, small, blue cells with large nuclei

--associated with paraneoplastic syndromes, including Cushing syndrome (ectopic production of ACTH) --> cushing syndrome characteristically associated with moon facies, central obesity, buffalo hump

99

A 57-yo man comes to the physician with concerns of a chronic nonproductive cough. He has smoked 1.5 packs per day for the past 40 years and occasionally drinks beer and hard liquor. He says he has occasional blood-tinged sputum after coughing, increasing fatigue, and a 4.5-kg weight loss in the past 5 months. A CXR shows a mass in the right middle lobe. Bronchoscopy reveals a grey-tan bronchial tumor. Biopsy shows a tumor composed of small uniform cells with dark round blue nuclei, little cytoplasm, and prominent crush artifact on H&E section. Immunohistochemical stains are positive for neuron specific enolase (NSE) and negative for lymphocyte common antigen (LCA). What is the diagnosis? What does a (+) NSE signify? What does a negative LCA signify?

small cell carcinoma

(+)NSE = neuroendocrine cell origin

(-)LCA = rules out lymphoma

100