DELETION OF CHROMOSOME ARM IP IN A MERKEL CELL-CARCINOMA (MCC)

A case of neuroendocrine skin carcinoma (Merkel cell carcinoma) with a deletion of the short arm of chromosome 1 (1p) as the sole chromosoma l abnormality was examined. The tumor originated in the skin of the le ft knee of a 67-year-old man. Histopathologic study showed an undiffer entiated small cell tumor which expressed neuron-specific enolase, chr omogranin, and cytokeratin (CAM 5.2). Cytogenetic analysis of a lymph node metastasis from the groin showed a pseudodiploid cell population with a deletion of the short arm of chromosome 1 as the only abnormali ty: 46,XY,del(1)(p36.1). In situ hybridization with the D 1Z2 probe sp ecific for the terminal band of I p confirmed the terminal deletion. T his is the first case of Merkel cell carcinoma in which only one chrom osomal abnormality has been observed. Loss of the terminal portion of Ip suggests that a tumor supressor gene on Ip plays a role in the path ogenesis of Merkel cell carcinoma. (C) 1994 Wiley-Liss, Inc.