[Pathogenesis of chronic disseminated acinar pulmonary tuberculosis: Oka's classification of pulmonary tuberculosis type IIB--a discussion through an analysis of two typical cases].

Purpose: To elucidate the pathogenesis of chronic disseminated acinar pulmonary tuberculosis (Oka's classification type IIB).

Subjects And Methods: The subjects are two cases of chronic disseminated acinar pulmonary tuberculosis. The pathogenesis were discussed through an analysis of their radiologic findings on admission and in the past.

Results: Case 1 is a 36 year-old woman whose complaint was slight fever and cervical lymphadenopathy for past four months. Disseminated granular shadows were observed in both lung fields on the chest X-ray on admission. The CT examination indicated that each granule was composed of circumscribed lesion within terminal or respiratory bronchiole, so called acinar lesion. It is compatible with pulmonary tuberculosis type IIB according to Oka's classification. The bronchial lavage yielded Mycobacterium tuberculosis. When compared the chest X-ray with that at 4 months before, it is suggested that the granular lesions were first spread hematogeneously and each granule thereafter ruptured into the airway. Case 2 is a 90 year-old man with slight fever and weight loss. The chest X-ray showed diffuse granular shadows. The CT examination indicated that the lung shadows were composed of disseminated acinar lesions. The diagnosis of tuberculosis was established by a bronchoscopic examination. Comparison of the chest X-ray findings between those at 3 years 9 months before and 8 months before suggests the bronchogenic development of the disease.

Conclusion: Through an analysis of these two cases, two kinds of pathogenesis were suggested in chronic disseminated acinar pulmonary tuberculosis; namely, one is hematogeneous route and the other is in bronchogenic route.