title: Cutaneous undifferentiated small (Merkel) cell carcinoma, that developed synchronously with multiple actinic keratoses, squamous cell carcinomas and basal cell carcinoma.
abstract: Merkel Cell Carcinoma (MCC) is an uncommon undifferentiated neuroendocrine tumor, arising in skin mainly on sun-exposed areas. We present an unusual case of primary cutaneous undifferentiated small cell carcinoma that co-existed with six other lesions; 2 actinic keratoses, 3 squamous-cell carcinomas and a basal-cell carcinoma. HE stained sections revealed MCC located in the mid-dermis, co-existing with severe actinic keratosis. Immunohistochemically, the tumor cells reacted to cytokeratin 20, epithelial membrane antigen, chromogranin and neuron specific enolase. This is an unusual case of cutaneous MCC co-existing with six other different lesions. The concurrent development of MCC, squamous-cell and basal-cell carcinoma in the same patient indicates the pluripotent epidermal stem cell origin of these tumors. Further research is needed to enlighten the factors inducing this divergent differentiation.
authors.affiliation: Department of Pathology, Medical Faculty, Gaziantep University, Gaziantep, Turkey.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Aydin
authors.forename: N Emrah
authors.initials: NE
authors.lastname: Koçer
authors.forename: Mehmet
authors.initials: M
authors.lastname: Bekerecioglu
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Sari
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D002280:Basal Cell Carcinoma / Q000150:complications / Q000473:pathology*; D015266:Carcinoma, Merkel Cell / Q000150:complications / Q000473:pathology* / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000150:complications / Q000473:pathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D007642:Keratosis / Q000150:complications / Q000473:pathology*; D009367:Neoplasm Staging; D009378:Neoplasms, Multiple Primary / Q000150:complications / Q000473:pathology* / Q000601:surgery; D012878:Skin Neoplasms / Q000150:complications / Q000473:pathology* / Q000601:surgery; D016896:Treatment Outcome; D014421:Turkey