Merkel cell carcinoma in situ arising in a trichilemmal cyst: A case report and literature review

Wei Su, Sonia M. Kheir, Brenda Berberian, Clay J. Cockerell

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

A 73-year-old man presented with a 4-mm asymptomatic, smooth, dome-shaped lesion on the right fourth finger with a clinical impression of a cyst/dermatofibroma. Histological examination showed a trichilemmal cyst with 3 nests of small blue round cells within the basal layer of the cyst lining. There were many mitotic figures and apoptotic bodies. The stain for cytokeratin 20 "decorated" the tumor cells with an unequivocal perinuclear dot-like pattern, confirming their Merkel cell origin. Dermal Merkel cell carcinoma (MCC) arising in association with benign adnexal tumors or cysts, with or without epithelial involvement, is a rare event. MCC in situ in this context has not been previously reported. The immunostain for cytokeratin 20 is an important ancillary study in diagnosing MCC. Our case supports the view that a subset of MCCs is of intraepithelial origin and underscores the clinical importance of surveillance for changes in an "innocent" cyst.

Original languageEnglish (US)
Pages (from-to)458-461
Number of pages4
JournalAmerican Journal of Dermatopathology
Volume30
Issue number5
DOIs
StatePublished - Oct 1 2008

Keywords

  • In situ
  • Merkel cell carcinoma
  • Trichilemmal cyst

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Dermatology

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