A case of Mycobacterium avium disease presenting as a solitary pulmonary nodule and resected under a suspicion of lung cancer

Abstract

A 43 year old female smoker was admitted to our hospital for evaluation of solitary pulmonary nodule (SPN). She had no symptoms, and no past history or family history that might suggest compromised defense against pulmonary infections. Physical examination and laboratory findings including humoral and cell-mediated immunity revealed no abnormality. The chest radiography taken 2 years ago looked normal, but those on admission showed SPN in a left lower field. Computed tomography (CT) revealed solitary elipsoid nodule in S5. Because two trials of transbronchial biopsy, brushing and washing could not give any diagnostic findings, thoracotomy was performed under tentative diagnosis of lung cancer. The lesion was located in the outer portion of S5 and was found to consist of 2 elastic hard nodule surrounded by a atelectasis with inflammation. The nodule had supprative substance with several acid fast bacilli, and its intraoperative pathology revealed epitheloid cell granulomas. The lesion was resected completely. In a mean while, seventy smooth colonies grew on an Ogawa egg medium, which was identified as M. avium by the probe analysis using SNAP TEST. The final diagnosis of pulmonary M. avium disease was made, and the patient was administered RFP, EB, OFLX, and CAM in a outpatient clinic. Some discussions were also made about CT findings of pulmonary M. avium complex disease developed in patients without any predisposing conditions.