Peripheral lung carcinomas associated with central fibrosis and mixed small cell and other histologic components

Three cases of peripheral small cell lung carcinoma (SCLC) with central fibrosis are presented. Central fibrosis is usually present in adenocarcinomas. Cases 1 and 2 are combined SCLCs with components of papillary adenocarcinoma, and case 3 is a mixed SCLC with a large cell component. Small cell components showed intermediate cell type in all cases. In cases 1 and 2, there was a gradual transition between small cell carcinoma and papillary adenocarcinoma. Small cell components showed Grimelius argyrophilia, but other neuroendocrine markers such as neuron specific enolase, chromogranin A, Leu-7 and synaptophysin were negative. The chest X-ray examination of case 1 demonstrated rapid enlargement of a tumor shadow, which was present two years before, for a recent year. Central fibrosis, coexistence of small cell carcinoma and papillary adenocarcinoma, and a change of growth rate in the chest X-ray may suggest that some SCLC derive from papillary adenocarcinomas.