Trabecular carcinoma of the skin: an ultrastructural study.

We report the electron microscopic studies of three trabecular carcinomas of the skin. The presence of neurosecretory granules in all three tumors suggests that trabecular carcinoma originates from one of the neurocrest derivatives, most probably, Merkel cells. The ultrastructural findings confirm Toker's original concept that trabecular carcinomas comprise a distinct group of skin tumor. The recognition of these tumors would enable one to make such a diagnosis on frozen section, which, in turn, might provide an opportunity for more specific cytochemical and immunofluorescent characterization.