title: Morpheaform Basal Cell Carcinomas With Areas of Predominantly Single-Cell Pattern of Infiltration: Diagnostic Utility of p63 and Cytokeratin.
abstract: BACKGROUND
  Morpheaform basal cell carcinoma (BCC) is a variant of BCC characterized by narrow strands and nests of basaloid cells with dense sclerotic stroma. The histologic extent often exceeds the clinical impression, leading to high recurrence rates after standard excision. The authors encountered a case with single-cell invasion distant from the main tumor. To date a systematic review of single-cell infiltration in morpheaform BCC has yet to be performed.
  
  
  METHODS
  Ten morpheaform BCCs, 10 nonmorpheaform aggressive BCCs, 5 desmoplastic trichoepitheliomas, and 2 microcystic adnexal carcinomas were identified by database search and confirmed on hematoxylin and eosin. Cases were evaluated by hematoxylin and eosin, immunohistochemical staining for p63, and (in a subset) broad-spectrum cytokeratin. Single-cell pattern was defined as individual cells, 2-cell clusters, or single-file invasion.
  
  
  RESULTS
  Three types of single-cell pattern were identified: intratumoral (single cells within the main tumor mass), peripheral, and distant. Single cells were typically a minor component relative to larger tumor nodules and strands. Eight of the 10 cases of morpheaform BCC demonstrated areas of single-cell pattern: 3 intratumoral, 3 peripheral, and 2 with distant spread (0.75 and 1.0 mm from the main tumor). Eight of the 10 aggressive BCC demonstrated a peripheral single-cell pattern. Rare intratumoral single cells were identified in 3/5 desmoplastic trichoepitheliomas and 1/2 microcystic adnexal carcinomas.
  
  
  CONCLUSIONS
  Single-cell pattern is frequently a component of morpheaform BCC. Tumor cells at a significant distance from the main component were unique to morpheaform BCC. Thus, when evaluating margins for morpheaform BCC, increased caution is recommended, and immunohistochemical stains for p63 or cytokeratins may be helpful.
authors.affiliation: Departments of *Pathology and †Dermatology, University of Michigan Health System, Ann Arbor MI; ‡Michigan Center for Translational Pathology, University of Michigan Health System, Ann Arbor MI; and §Department of Urology, Vattikutti Urology Institute, Henry Ford Health System, Detroit, MI.
authors.forename: Ellen
authors.initials: E
authors.lastname: East
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Fullen
authors.forename: David
authors.initials: D
authors.lastname: Arps
authors.forename: Rajiv M
authors.initials: RM
authors.lastname: Patel
authors.forename: Nallasivam
authors.initials: N
authors.lastname: Palanisamy
authors.forename: Shannon
authors.initials: S
authors.lastname: Carskadon
authors.forename: Paul W
authors.initials: PW
authors.lastname: Harms
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D001706:Biopsy; D002280:Basal Cell Carcinoma / Q000737:chemistry* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000032:analysis*; D009361:Neoplasm Invasiveness; D011237:Predictive Value of Tests; D012878:Skin Neoplasms / Q000737:chemistry* / Q000473:pathology; D014157:Transcription Factors / Q000032:analysis*; D025521:Tumor Suppressor Proteins / Q000032:analysis*
chemical_list: D014408:Biomarkers, Tumor; C115051:TP63 protein, human; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D007633:Keratins