A Case of Congenital Cystic Adenomatoid Malformation Infected with Mycobacterium avium-intracellulare Complex
A 25-year-old male without a history of smoking presented with a 1-week history of cough and right-sided back pain when coughing. The patient had a history of one hospital admission due to pneumonia approximately ten years prior to the current presentation and complained of intermittent cough over the intervening ten years.\nA physical examination identified decreased breathing sounds over the right lower lung without other findings. A complete blood count test, liver function test and urine analysis were normal. His erythrocyte sedimentation rate was 61 mm/hr and his high-sensitivity C-reactive protein was 3.86 mg/dL. Chest radiography showed an abnormal mass-like shadow in the right lower lung (). Contrast-enhanced computed tomography (CT) revealed an 11 cm solid, cystic mixed mass in the right lower lobe without a feeding vessel from the descending aorta (). Bronchoscopy disclosed purulent secretion from the posterior basal segmental bronchus of the right lower lobe. A pulmonary function test was normal.\nSubsequently, the patient underwent a right lower lobectomy by video-assisted thoracoscopic surgery. A macroscopic examination showed a massive cavitation with multiloculated cysts of varying size within the lesion and pleural fibrosis (). Microscopically, the specimen consisted of multiple cysts () which were lined by cuboidal-to-ciliated pseudostratified columnar epithelium, and some cysts contained extensive secondary inflammation (). These histological features were consistent with typical type I CCAM. In addition, a microscopic examination revealed a noticeable caseous granulomatous inflammation in the cyst walls (). The necrotic center was surrounded by epithelioid histiocytes and then by a rim of lymphocytes (). Forty colony forming units of non-tuberculosis mycobacterium (NTM) were isolated from a bronchial wash specimen. Furthermore, resected lung tissue homogenates were positive for MAC by real-time polymerase chain reaction (). The postoperative course was uneventful without anti-mycobacterial treatment. Two years after surgery, chest radiography showed a well-expanded right lung without lesions.