A case of pulmonary histoplasmosis difficult to differentiate with lung cancer

Abstract

A 47-year-old man consulted our hospital for a coin lesion on a routine chest X-ray with no complaints. Chest CT showed a nodule in the right lower lobe. Bronchoscopic examination revealed no malignancy and the nodule had not changed in size nor character. Because lung cancer had not been ruled out radiologically and pathologically, thoracoscopic partial resection was performed. At first, pulmonary cryptococcosis was suspected, but immunohistochemistry was not compatible. At last, it was diagnosed as pulmonary histoplasmosis by the detection of rRNA of H. capsulatum from a paraffin-embedded tissue sample. Pulmonary histoplasmosis is rare in Japan. Because the number of imported mycoses in Japan is expected to increase, pulmorary histoplasmosis should be considered in the differential diagnosis and therapy of pulmonary nodules.