title: Combined intraepidermal neuroendocrine (Merkel cell) and squamous cell carcinoma in situ with CM2B4 negativity and p53 overexpression(*).
abstract: Primary cutaneous neuroendocrine carcinoma, also known as Merkel cell carcinoma (MCC), usually presents as a dermal and/or subcutaneous tumor. Rarely, it is confined to the epidermis or adnexal epithelium [MCC in situ (MCCIS)]. Little is known about the spectrum of features and biology of MCCIS. Herein, we report a case of MCCIS arising on the cheek of a 77-year-old Caucasian male, which was associated with squamous cell carcinoma in situ. The tumor cells of both the neuroendocrine and squamous components prominently involved adnexal structures but did not invade the dermis. The tumor cells with neuroendocrine features were immunoreactive for cytokeratin-20, chromogranin and synaptophysin. They also expressed p53 but were non-reactive with the monoclonal antibody CM2B4. Lack of labeling for CM2B4 is in keeping with prior observations of combined squamous and MCC. Our findings support the concept of a distinct subtype of virus-independent cutaneous neuroendocrine carcinoma that differs from conventional MCC. The observed overexpression of p53 suggests that the development of this tumor type may be related to chronic ultraviolet damage.
authors.affiliation: Department of Pathology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.
authors.forename: Belinda H
authors.initials: BH
authors.lastname: Tan
authors.forename: Klaus J
authors.initials: KJ
authors.lastname: Busam
authors.forename: Melissa P
authors.initials: MP
authors.lastname: Pulitzer
mesh_terms: D000368:Aged; D000911:Antibodies, Monoclonal / Q000737:chemistry; D000912:Antibodies, Neoplasm / Q000737:chemistry; D015266:Carcinoma, Merkel Cell / Q000378:metabolism / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D016609:Neoplasms, Second Primary / Q000378:metabolism / Q000473:pathology; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis*
chemical_list: D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53