Clinical Analysis of Pulmonary Mycobacterium kansasii Disease

To investigate the clinical aspects of pulmonary Mycobacterium kansasii (M. kansasii) disease. In 25 patients who satisfied the diagnostic criteria of the American Thoracic Society, we retrospectively evaluated the background, diagnostic methods, laboratory findings, radiological findings, treatment and prognosis. The median age was 61 years old (20 males, 5 females). Nine patients (36%) had no underlying diseases. The definite diagnosis was obtained by expectorated sputum in 10 cases, bronchoscopy in 12, video-assisted thoracic surgery in 2 and CT-guided lung biopsy in 1. The positive response rate for QuantiFERON (QFT) was 27%. Radiological changes in pulmonary M. kansasii disease were frequently shown in the upper lobe and bilateral lung fields, but the extent of the lesions was limited within ten segments of the lung. Infiltration shadows or centrilobular small nodules with bronchiectasis, as well as cavities, were recognized in over half of all patients. Combined chemotherapy was given to 16 of 25 patients with a favorable effect in 15. The remaining 9 patients consisted of 2 patients who required surgical treatment, one who died of other complications and six with no treatment because of hospital transfer. Patients with pulmonary M. kansasii disease may have radiological findings without cavitary disease described in previous studies. Therefore it is better to perform a bronchoscopic examination to make an accurate diagnosis and do smear and culture examinations for acid-fast bacilli.