Clinical studies on the pathogenetic factors of cavitary and nodular bronchiectatic types in pulmonary Mycobacterium avium complex disease

: We investigated the clinical, laboratory and radiological findings of 273 newly diagnosed cases of pulmonary Mycobacterium avium complex (MAC) disease, who were diagnosed in our hospital during 7 years from January 1996 to December 2002. Radiological findings of all cases were classified at the time of diagnosis into 2 patterns, the cavitary (Cav) type and the nodular bronchiectasis (NB) type. Clinical and laboratory findings at the time of diagnosis of 44 death cases were compared with those of 273 newly diagnoses cases, to analyze the prognostic factors of this disease. MAC disease cases showed a marked increase in number in recent years, but only in women. Mean age at the first visit was 65.7 years in men and 63.2 years in women, and when limited to fatal cases, it was 72.3 years in men and 69.4 years in women. Low body weight in terms of body mass index (BMI) and moderately low serum albumin level were found at the time of the first hospital visit in all the newly diagnosed and death cases. In the fatal cases, the peripheral blood lymphocyte counts revealed a relatively smaller number than the normal range, and the PPD skin test showed a negative reaction in 57.7% of all cases, suggesting the presence of lowered cell-mediated immunity at the time of diagnosis. Whether malnutrition occurs as a result of MAC disease or the individuals with lower nutrition level are easy to develop to MAC disease remains to be clarified. In regard to radiological findings, many cavitary (Cav) type cases were found in men and nodular bronchiectasis (NB) type in women among newly diagnosed cases, while the cavitary type was observed in many in both men and women fatal cases. The mean duration period from diagnosis to death was 28.3 months in men and 60.2 months in women, showing a longer survival after diagnosis, perhaps due to earlier hospital visits by women. The average age at death was 74.4 years old in men and 73.8 years old in women, and the two radiological patterns did not change throughout the entire disease course.