title: Management of trichilemmal carcinoma: an update and comprehensive review of the literature.
abstract: BACKGROUND
  Trichilemmal carcinoma (TC) is a rare malignant adnexal neoplasm with outer root sheath differentiation. Most cases have been treated by surgical excision with a few recurrences. There have been 6 case reports of TC treated with Mohs micrographic surgery (MMS).
  
  
  OBJECTIVE
  To perform an updated review of the literature regarding management of this uncommon tumor.
  
  
  METHODS
  A comprehensive literature review was conducted by searching the PubMed database using the keywords trichilemmal carcinoma, tricholemmal carcinoma, and tricholemmocarcinoma.
  
  
  RESULTS
  There have been 103 reported cases of TC, and most of these were treated with surgical excisions. Of the 35 cases with follow-up data, 3 reported local recurrences and 1 had subsequent metastatic disease. There are 6 cases of TC successfully treated with MMS without any recurrence. In addition, we report the seventh case of TC successfully treated with MMS. Other reported treatment modalities include imiquimod and excision with frozen sections. Histopathologically, the distinction between TC and squamous cell carcinoma with clear cell differentiation has been debated in the literature.
  
  
  CONCLUSIONS
  Trichilemmal carcinoma is a rare neoplasm that may behave aggressively. The recommended treatment should be a complete surgical excision with histologic confirmation of clear margins. In cases where tissue sparing or cosmesis is important, MMS may be considered.
authors.affiliation: *Both authors are affiliated with the Division of Dermatology, San Diego Medical Center, University of California, San Diego, CA.
authors.forename: Michael Shane
authors.initials: MS
authors.lastname: Hamman
authors.forename: Shang I
authors.initials: SI
authors.lastname: Brian Jiang
mesh_terms: D000369:Aged, 80 and over; D000634:Aminoquinolines / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000627:therapeutic use; D002277:Carcinoma / Q000188:drug therapy / Q000453:epidemiology / Q000209:etiology / Q000473:pathology* / Q000601:surgery*; D018859:Hair Follicle; D006801:Humans; D000077271:Imiquimod; D008297:Male; D015580:Mohs Surgery; D012878:Skin Neoplasms / Q000188:drug therapy / Q000453:epidemiology / Q000209:etiology / Q000473:pathology* / Q000601:surgery*
chemical_list: D000634:Aminoquinolines; D000970:Antineoplastic Agents; D000077271:Imiquimod