Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 38-year-old man is evaluated for a 6-month history of dyspnea on exertion. He has gastroesophageal reflux disease and Raynaud phenomenon. He does not smoke and has no cough or wheezing. Current medications are lansoprazole and amlodipine.

On physical examination, vital signs are normal. Oxygen saturation is 91% breathing ambient air. He has scattered telangiectasias on the face and trunk and sclerodactyly. Lung fields are clear on auscultation.

The only abnormality on pulmonary function testing is a DLCO of 43% of predicted. High-resolution CT of the chest shows no evidence of parenchymal lung disease.

Which of the following is the most likely diagnosis?

A. Cryptogenic organizing pneumonia
B. Lymphangioleiomyomatosis
C. Lymphoid interstitial pneumonia
D. Pulmonary arterial hypertension

MKSAP Answer and Critique

The correct answer is D. Pulmonary arterial hypertension.

The most likely diagnosis is pulmonary arterial hypertension. Pulmonary involvement is frequent (greater than 70%) in patients with systemic sclerosis and can be symptomatic and disabling. The two principal clinical manifestations are interstitial lung disease and pulmonary vascular disease. Pulmonary vascular disease leading to pulmonary arterial hypertension may occur secondary to interstitial lung disease (typically in diffuse cutaneous systemic sclerosis) or as an isolated process (typically in limited cutaneous systemic sclerosis). This patient has several features of limited cutaneous systemic sclerosis with CREST syndrome (a condition defined by calcinosis cutis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasias). Patients are usually asymptomatic in early disease but later develop dyspnea on exertion and diminished exercise tolerance. Severe disease can lead to right-sided heart failure. Chest imaging is often normal and pulmonary function tests demonstrate a reduced DLCO with normal lung volumes.

Organizing pneumonia is a patchy process that involves proliferation of granulation tissue within alveolar ducts, alveolar spaces, and surrounding areas of chronic inflammation. There are many known causes of this pattern, including acute infections and autoimmune disorders such as rheumatoid arthritis. The term cryptogenic organizing pneumonia (COP) is reserved for individuals who have this pattern but do not have a clear associated cause. Patients with COP will typically present with symptoms during 6 to 8 weeks that mimic community-acquired pneumonia. Evaluation typically demonstrates bilateral diffuse alveolar opacities on chest radiograph with normal lung volumes. This patient’s presentation is not consistent with cryptogenic organizing pneumonia.

Lymphangioleiomyomatosis is a multisystem disease that almost exclusively affects young women. Pulmonary complications are prominent and include diffuse pulmonary cysts, pneumothorax, chylous pleural effusions, and obstructive airways disease. Lymphangioleiomyomatosis would be very unlikely in a patient with an unremarkable chest radiograph.

Lymphoid interstitial pneumonia is an interstitial lung disease characterized by lymphocytic infiltration of the pulmonary interstitium. It is observed in patients with Sjögren’s syndrome and viral infections, especially HIV. Patients with lymphoid interstitial pneumonia often have crackles on the pulmonary examination, interstitial infiltrates on chest radiography, and decreased lung volumes and diffusing capacity on pulmonary function testing.

Key Point

• Pulmonary arterial hypertension is commonly associated with connective tissue diseases, such as limited cutaneous systemic sclerosis.

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