[A case of pulmonary Mycobacterium avium complex disease complicated by interstitial pneumonia with collagen vascular disease].

A 45-year-old woman with scleroderma for 15 years duration, rheumatoid arthritis in the past five years, and interstitial pneumonia in the past two years had been followed at OPD. Although sputum had appeared and cough had increased since January 2002, there was no obvious abnormal findings on chest X-ray. Later, as a chest X-ray revealed an infiltrative shadow with cavity in the right lower lung field, we suspected pulmonary tuberculosis and performed the direct smear examination of sputum immediately. As acid-fast bacilli were positive (Gaffky 10) and the polymerase chain reaction (PCR) test was positive for only Mycobacterium avium, we diagnosed the case as pulmonary nontuberculous mycobacterial disease. This case was thought to be pulmonary nontuberculous mycobacterial disease complicated with interstitial pneumonia with collagen vascular disease as a secondary infectious type, and as the cause of the disease, the decrease of the local pulmonary defence mechanism due to pre-existing pulmonary lesions was suspected.