title: Diagnostic pitfalls of Merkel cell carcinoma and dramatic response to chemotherapy.
abstract: Merkel cell carcinoma (MCC) is an unusual malignant tumor that arises from neuroendocrine cells with features of epithelial differentiation. We describe a MCC patient with unusual clinical, histopathological, and immunohistochemical features. Although the microscopic, immunohistochemical, and ultrastructural characteristics of MCC have been well defined, diagnostic difficulties remain, particularly in distinguishing it from lymphoma involving the skin, as suggested by our case. This is an unusual case in which dense lymphoid infiltration masked the true tumor. All the immunohistochemical markers of MCC except neuron-specific enolase (NSE) were negative. The dramatic response to primary chemotherapy was also very noteworthy.
authors.affiliation: Department of Dermatology, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Korea.
authors.forename: S F
authors.initials: SF
authors.lastname: Chang
authors.forename: J W
authors.initials: JW
authors.lastname: Suh
authors.forename: J H
authors.initials: JH
authors.lastname: Choi
authors.forename: G S
authors.initials: GS
authors.lastname: Yoon
authors.forename: J
authors.initials: J
authors.lastname: Huh
authors.forename: K J
authors.initials: KJ
authors.lastname: Sung
authors.forename: K C
authors.initials: KC
authors.lastname: Moon
authors.forename: W G
authors.initials: WG
authors.lastname: Kim
authors.forename: J K
authors.initials: JK
authors.lastname: Koh
mesh_terms: D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D015266:Carcinoma, Merkel Cell / Q000175:diagnosis* / Q000188:drug therapy; D003520:Cyclophosphamide / Q000008:administration & dosage; D003937:Diagnosis, Differential; D004317:Doxorubicin / Q000008:administration & dosage; D006801:Humans; D008223:Lymphoma / Q000175:diagnosis; D008297:Male; D011239:Prednisolone / Q000008:administration & dosage; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000188:drug therapy; D014750:Vincristine / Q000008:administration & dosage
chemical_list: D014750:Vincristine; D004317:Doxorubicin; D003520:Cyclophosphamide; D011239:Prednisolone