2020 Volume 34 Issue 1 Pages 57-61
A 46-year-old Japanese woman, who had stayed in South America for a long time, presented with an abnormal shadow on a medical checkup. Chest computed tomography (CT) showed a nodule of 20 mm in diameter in the right lower lung. CT-guided lung biopsy revealed a non-malignant nodule. Moreover, infections, such as nontuberculous mycobacteriosis and mycosis, were not observed. The patient was expecting to receive medical treatment upon returning to Japan. Thus, she visited her previous hospital and underwent endobronchial ultrasonic-guided transbronchial needle aspiration for the pulmonary nodule. Results revealed an inflammatory granuloma with coagulation necrosis. Because the diagnosis of a malignant tumor had not been ruled out, she was admitted to our hospital for surgical resection. For diagnosis and treatment, lung wedge resection was performed under video-assisted thoracic surgery. Pathological findings revealed that the lesion was a non-neoplastic mass: an epithelioid cell granuloma with coagulation necrosis. The mycobacterium smear was negative. However, the Grocott smear revealed several round or oval mycotic bodies, such as yeast, in the lesion. After surgery, based on serum examination, the patient tested positive for anti-histoplasma antibody, and she was finally diagnosed with pulmonary histoplasmosis. Because the patient had a normal immune response and did not present with symptoms, she did not receive adjuvant antifungal drug therapy in accordance with the Infectious Diseases Society of America guideline. The postoperative course was uneventful. At 20 months after surgery, there had been no relapse. Our case report reveals that pulmonary histoplasmosis is difficult to differentiate from lung cancer.