Question 162
A 62-year-old male who has not seen a doctor in 20 years presents to a family physician at his wife’s insistence. Over the last 4 months he has had a chronic cough, occasional pain in his chest, and 20 lb. of weight loss. A chest x-ray reveals a mass in the upper lobe of the left lung. Biopsy reveals neoplastic squamous cells. Of the following, what was the most likely etiology of his neoplasm?
A. Cigarette smoke
B. Asbestos exposure
C. Radon exposure
D. Arsenic exposure
E. Past contact with radioactive substance
Answer for Question 162
Answer: A (Cigarette smoke)
Explanation: All of the above exposures (i.e., cigarette smoke, asbestos, radon, arsenic, and radiation) are risk factors for lung carcinoma; however, the most common etiology of lung cancer is cigarette smoke.
Question 163
A 62-year-old male with a 45 pack year smoking history undergoes chest x-ray as a component of a pre-surgical evaluation for elective cholecystectomy. The x-ray reveals a mass in the lower lobe of the left lung. Laboratory testing reveals an ionized calcium concentration of 6.7 mg/dL (normal range: 4.56-5.40 mg/dL). A biopsy of the mass would most likely reveal which of the following?
A. Benign cartilage
B. Epithelial cells with intercellular bridges
C. Caseating granulomas
D. Mass of neutrophils admixed with bacterial cocci
E. Mass of abnormally connected arteries and veins
Answer for Question 163
Answer: B (Epithelial cells with intercellular bridges)
Explanation: Given the history of smoking and the fact that lung cancer is often asymptomatic, the finding of an incidental mass on chest x-ray is concerning for a neoplasm. Squamous cell carcinoma produces PTH-related peptide, which can cause an elevated concentration of calcium. The features of squamous cell carcinoma include intercellular bridges and keratin pearls. A pulmonary hamartoma (benign cartilage) would not cause hypercalcemia. Although sarcoidosis can produce elevated concentrations of calcium and is often found in the lung, most sarcoidosis granulomas are non-caseating. Neither an abscess (i.e., a mass of neutrophils admixed with bacterial cocci) or an arteriovenous malformation (i.e., a mass of abnormally connected arteries and veins) are commonly associated with elevated concentrations of calcium, and he has no fever, or other symptoms indicative of an infection.
Question 164
A 65-year-old male with a history of hypertension, diabetes mellitus type II, and a 45 pack-year smoking history with chronic cough presents to an acute care clinic with complaints that he has gotten very sensitive to heat lately and cannot tolerate working outside in his garden for very long. Physical examination reveals drooping of his left upper eyelid and constriction of the left pupil compared to the right side. In addition, the left eye appears somewhat sunken in the orbit. Of the following, which procedure is most likely to identify the cause of his condition?
A. CT scan of the head
B. X-ray of the chest
C. Echocardiogram
D. Lumbar puncture
E. MRI of the pelvis
Answer for Question 164
Answer: B (X-ray of the chest)
Explanation: The patient has features of Horner syndrome (enophthalmos – the sunken nature of the eye; ptosis – the drooping of the upper eyelid; miosis – constriction of the pupil; and the heat intolerance is a symptom of anhidrosis, which is lack of sweating). Given his age and smoking history, a lung neoplasm at the apex of the lung (i.e., a Pancoast tumor) would be a strong possible cause. Of the choices, an x-ray of the chest would be most likely to reveal the tumor.
Question 165
A 54-year-old male with a past medical history of hypertension and a 40 pack-year smoking history is undergoing a routine physical examination prior to a scheduled inguinal hernia repair. Physical examination reveals a small fixed palpable node above the left clavicle. A fine needle aspirate of this node reveals small cells with a high nuclear:cytoplasm ratio and high mitotic rate. No glandular formation or keratin production is evident. Molecular analysis of the cells would most likely reveal which of the following genetic abnormalities?
A. RB mutation
B. EGFR mutation
C. ALK rearrangement
D. p16/CDKN2A mutation
E. PTEN mutation
Answer for Question 165
Answer: A (RB mutation)
Explanation: Given the age of the patient and smoking history, he is at risk for lung cancer. A palpable supraclavicular node (i.e., Virchow node) is characteristic for metastatic spread of a lung carcinoma. The cellular features are indicative of a small cell carcinoma, and the neoplasm has no features of either adenocarcinoma or squamous cell carcinoma. Over 90% of small cell carcinomas have a mutation of RB. EGFR mutations and ALK rearrangements are characteristic of adenocarcinomas, and p16/CDKN2A are very uncommonly found in small cell carcinoma and are more characteristic of non-small cell carcinoma. PTEN mutation is commonly associated with endometrial carcinoma and melanoma; however, it is uncommonly (6-9%) associated with lung carcinoma, and predominantly with squamous cell carcinoma.