A 21-year-old male was referred to our hospital because of a cough, fever, and progressive lung lesion on his chest radiograph. He was a non-smoker. A cystic mass had been noticed on the chest radiograph at a routine health check 6 months earlier (Fig. 1A). He was given a presumptive diagnosis of pulmonary tuberculosis without bacteriologic confirmation. The patient had been taking anti-tuberculosis medication for 6 months. However, the mass increased in size (Fig. 1B) and new symptoms developed, such as the cough and fever. Consequently, he was referred to our hospital.
On admission, his body temperature was 39C. His white blood cell count was 8,460/microL, the erythrocyte sedimentation rate was 74 mm/hr, and C-reactive protein increased to 5.39 mg/dL. A human immunodeficiency virus antibody test was negative. A chest radiograph and computed tomography revealed a huge, multi-septated cystic mass in the right upper lobe (Fig. 2A).
Numerous acid-fast bacilli (AFB) were seen in multiple sputum specimens. However, nucleic acid amplification tests for Mycobacterium tuberculosis in the sputum specimens were negative using a commercial DNA probe (Gen-Probe amplified Mycobacterium tuberculosis direct test, Gen-Probe, San Diego, CA, USA). The results of both a tuberculin skin test and serum interferon gamma assay (QuantiFERON-TB Gold, Cellestis, Victoria, Australia) were negative. A polymerase chain reaction method used to examine AFB-positive sputum specimens was for identification of the causative agent. The result was positive for M. avium.
Based on the clinical findings and laboratory data, our diagnosis was M. avium infection combined with congenital cystic lung disease. The antibiotic therapy was changed to clarithromycin (1,000 mg/day), rifampicin (600 mg/day), ethambutol (800 mg/day), and streptomycin (1 g intramuscularly three times per week).
The patient underwent a right upper lobectomy 3 weeks later for confirmative diagnosis and treatment of complicated congenital cystic lesion. The resected lung contained a 2.5 x 2 cm intrapulmonary bronchogenic cyst and a 5 x 3.5 cm destructive cavitary lesion near the bronchogenic cyst in the right-upper lobe (Fig. 2B). Extensive granulomatous inflammation with caseous necrosis was found within the destructive cavitary lesion (Fig. 2C), and ciliated columnar epithelium without granuloma was found within the bronchogenic cyst (Fig. 2D).
Numerous mycobacterial colonies were cultured from multiple sputum specimens and excised lung tissue. All were subsequently identified as M. avium. The isolate was susceptible to clarithromycin. The patient's postoperative course was uneventful, and he was discharged without complications. He received postoperative antibiotic therapy for 6 months.
A 21-year-old man with Mycobacterium avium infection combined with a bronchogenic cyst. (A) Chest computed tomography (CT) revealed a multi-loculated cystic mass with bronchiolitis in the right upper lobe.