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A 54-year-old man is admitted to the hospital with cough and dyspnea, which over a period of years has led to marked respiratory embarrassment and cyanosis. Chest x-ray film of the lungs shows bilateral lower lobe ground-glass infiltrates. Wedge biopsy of the lung demonstrates airspaces
filled with macrophages containing lipid, periodic acid-Schiff (PAS)-positive granules, and lamellar bodies. There is an accompanying interstitial pneumonitis, hyperplasia of the septal lining epithelial cells, and desquamation of epithelial cells into alveoli. The lamellar bodies
within the macrophages are composed of which of the following?

A. Amyloid

B. Calcitonin

C. Fibrin

D. Hemosiderin

E. Surfactant

Explanation:

Full explanation in first response.
 

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A 54-year-old man is admitted to the hospital with cough and dyspnea

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Explanation:

The correct answer is E. The disease is desquamative interstitial pneumonitis (DIP), which is
an idiopathic process related to idiopathic interstitial fibrosis. DIP may respond to steroid
therapy but may also progress to end-stage lung disease. The lamellar (layered) bodies within
macrophages contain surfactant derived from type II pneumocytes.

Amyloid (choice A) is deposited extracellularly and is not part of the DIP process.

Calcitonin (choice B) is found in medullary carcinoma of the thyroid.

Fibrin deposition (choice C) can be part of the DIP process, but occurs as eosinophilic
extracellular deposits, rather than as intracellular lamellar bodies.

Hemosiderin (choice D) can accumulate in pulmonary macrophages, usually in the setting of
congestive heart failure with microhemorrhages, and produces golden brown granules.
 
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