USMLE-Rx Step 1 Practice Q's

USMLE-Rx Step 1 Qmax Challenge #1632

Check out today’s Step 1 Qmax Question Challenge.

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USMLE-Rx Step 1 Qmax Challenge #1632A 74-year-old patient presents with increased shortness of breath. A sputum sample reveals golden-brown beaded fibers, like those shown in the image, which result from iron- and protein-coated fibers. On CT scan, a peripheral lesion abbuting the lungs is visualized. A particular pneumoconiosis is suspected.

Which of the following is the likely cause of the patient’s condition?

A. Autoimmune attack of lung parenchyma
B. Idiopathic (unknown) origin
C. Living for years in a city with polluted air
D. Long-term complication of steroid abuse
E. Reactivation of a contained primary disease
F. Working in a coal mine for 40 years
G. Working in a shipyard for 40 years

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7 replies »

  1. The correct answer is G. Working in a shipyard is associated with asbestos exposure. Chronic inhalation of asbestos fibers can result in asbestosis, which is marked histologically by ferruginous bodies that stain rusty red with H&E. Asbestosis, unlike most other pneumoconioses, results in marked predisposition to bronchogenic carcinoma and to malignant mesothelioma. Smoking and asbestos exposure together greatly increase one’s risk of developing bronchogenic carcinoma. The CT shown here demonstrates one sequela of asbestos exposure, calcified pleural plaques.

    A is not correct. Asbestosis is not related to an autoimmune phenomenon.

    B is not correct. The cause of asbestosis is the inhalation of asbestos fibers into the lungs. Idiopathic restrictive lung diseases include sarcoidosis and idiopathic pulmonary fibrosis.

    C is not correct. Living in an urban area for years can cause anthracosis, which is a result of inhalation of carbon dust. It is characterized histologically by carbon-carrying macrophages and results in irregular black patches visible on gross inspection. Anthracosis is harmless.

    D is not correct. Ferruginous bodies and ivory-white pleural plaques are not long-term sequelae of steroid abuse.

    E is not correct. Tuberculosis has Ghon complexes in primary infection. Cavitary lesions are present in secondary reactivation.

    F is not correct.
    Working in a coal mine is a risk factor for both “coal workers’ pneumoconiosis” and silicosis. It may be difficult to differentiate between the two, given their similar lung pathology and patient history. Look for findings of “black lungs” on pathology or “eggshell calcifications” on CT to aid in developing the proper diagnosis of coal workers’ pneumonconiosis or silicosis, respectively.

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