Drug-induced lung disease due to topical minoxidil.

A 55-year-old man presented to our institution with abnormal chest X-ray shadows. Chest computed tomography (CT) showed left-sided interlobular septal thickening; thus, we suspected lymphangitis carcinomatosis and other disorders that show similar CT findings. Bronchoscopy and laboratory and imaging studies yielded no diagnostic findings. Pulmonary shadows during follow-up spontaneously improved then worsened. Thoracoscopic lung biopsy samples showed interstitial pneumonia and granulomas but the etiology of the pulmonary lesion could not be determined. At seven years after presentation, the patient's pulmonary shadows had gradually deteriorated, and he reported using topical minoxidil. His history of minoxidil use was linked to changes in the pulmonary shadows. The diagnostic delay was due to the patient's hesitancy to report drugs obtained online and the difficulty in obtaining such a history.