[Merkel cell tumor]

Two cases of skin carcinoma which display endocrine differentiation are reported. In the relevant literature, these neoplasms are considered to be of Merkel cells lineage. These two carcinomas demonstrated salient morphological features. The first tumor contained small aggregates of cells with a deeply indented nucleus. It is postulated that these formations represent foci of Merkel cells maturation. It is suggested that this distinctive focal histological feature may permit recognition of these neoplasms. The second tumor exhibited an admixture of endocrine and epidermoid differentiation. Such observations prompt us to postulate that Merkel cells and keratinocytes originate from the same stem cell.