[The contribution of ultrastructural analysis to the diagnosis of bronchoalveolar cancers].

The authors discuss comprehensive observations on three cases of broncho-alveolar cell carcinoma covering different anatomo-clinical aspects. The first case was diffuse and characterised radiologically by soft nodular shadows bilaterally, the second had lobar opacities and in the third the tumour was locally limited. Histological study showed two cellular types, in variable proportion according to the case, namely 1. mucus cells and 2. cells containing rounded osmiophilic secretory granules, identified on ultra-structure as Clara cells. In the diffuse form mucus cells predominated. They were absent in the third case where the tumour consisted solely of Clara cells. Thus, the Clara cell seemed to be the characteristic cell of alveolar cell carcinoma. Alveolar cell carcinoma can be diagnosed today by fibre-optic bronchoscopy with transbronchial biopsy and it is fundamental to arrive at a precise cellular diagnosis, which can only be achieved by ultra-structural studies.