A case of atypical mycobacterial infection which was strongly suspected as stage IV lung cancer

Abstract

An 81-year-old male consulted a doctor due to a tumor shadow of 3.5 cm in diameter in the apex of the right lung found on chest radiograph at his 2008 health check. Bronchoscopy did not yield a diagnosis of lung cancer. However, swollen bilateral adrenal glands were noted. He was referred to our hospital for diagnosis and treatment. On plain CT, tumor of the apex of the right lung with ipsilateral hilar lymphadenopathy and swollen bilateral adrenal glands were detected, and subsequent FDG-PET confirmed abnormal accumulation in the same regions. These data suggested he had advanced lung cancer with metastases to the bilateral adrenal glands as well as hilar lymph nodes, cT3N1M1 stage IV. CT-guided needle biopsy to determine the tissue type of the cancer for the planning of chemotherapy showed no malignancy but granulation tissue of unknown origin with caseous necrosis. In order to reach a definitive diagnosis, VATS was performed, and examination of the resected specimen resulted in the pathological diagnosis of epithelioid granuloma. Although acid-fast bacteria were not detected by PCR of the specimen, M. avium complex was isolated on 3-week culture; thus, a diagnosis of pulmonary atypical mycobacteriosis was finally reached. Excision biopsy is a significant strategy in cases of pulmonary lesions mimicking advanced lung cancer.