The carcinomatous transformation of bronchial carcinoids.

A series of 142 bronchial carcinoids studied on repeated endoscopic biopsies and surgical specimens (mostly lobectomies) was revised in order to distinguish the cases in which an increasing malignancy occurred and evolved up to the transformation into lung carcinomas. Twenty-one cases (14.79 per cent) were marked out (Table 1), of which ten were atypical carcinoids with increasing nuclear anaplasia (hyperchromaticity, pleomorphic and monstrous nuclei, prominent nucleoli), mitoses, sometimes presence of intracytoplasmic keratin granules, etc.; three of these cases presented liver, lymph node or rib metastases with histotypical structures. Ten bronchial carcinoids were carcinomatously transformed: four cases were macrocellular (large cell anaplastic) carcinomas, two other epidermoid ones and four became cylindrocubic carcinomas: all these malignantly transformed carcinoids presented transition areas between the carcinoid and the carcinomatous structures. In a last case, the bronchial carcinoid coexisted with a macrocellular carcinoma developed extrabronchially without overt structural relationships. None of the investigated cases became a macrocellular (oat cell) carcinoma.