MERKEL CELL TUMOR-LIKE NEUROENDOCRINE CARCINOMA-ASSOCIATED WITH THE SUBMANDIBULAR-GLAND - REPORT OF A CASE WITH CYTOLOGIC, IMMUNOHISTOCHEMICAL, ELECTRON-MICROSCOPIC AND FLOW CYTOMETRIC STUDIES

We report a rare case of primary Merkel cell tumor (MCT)-like neuroend ocrine carcinoma (i.e., small cell carcinoma) associated with the subm andibular gland in a 73-year-old man. Despite the lack of a known skin primary, the tumor exhibited cytomorphologic (predominant single cell s with ''intermediate filament buttons'' in the background), ultrastru ctural (dense core granules and a globular aggregate of intermediate f ilaments) and immunohistochemical (paranuclear globular coexpression o f cytokeratin and neurofilaments) features identical to that of MCT. T he tumor contained an aneuploid peak with DNA index of 1.1 and an S ph ase of 20.5%. The tumor measured 5.8 cm and was situated between the s kin and submandibular gland, with which it was closely associated brit separated by connective tissue. The literature on MCT without a known skin primary is reviewed, and the cytomorphologic features that allow the distinction between MCT, lymphoma and oat cell carcinoma are disc ussed.