title: Cellular digital fibromas: distinctive CD34-positive lesions that may mimic dermatofibrosarcoma protuberans.
abstract: BACKGROUND
  Digital fibromas are common benign acral tumors typically reported as angiofibromas (AFs) or acquired digital fibrokeratomas (ADFs). Cellular variants are not well recognized.
  
  
  METHODS
  We collected 14 acral fibrocytic lesions showing a spindle cell morphology from our files, and evaluated CD34, Factor XIIIa, epithelial membrane antigen (EMA), and S100 protein staining of these lesions. We compared the histologic and immunohistochemical features of these cellular fibromas with five digital AFs, five ADFs, and five digital dermatofibromas.
  
  
  RESULTS
  The 14 cellular digital fibromas showed intersecting fascicles of thin delicate bland spindle cells in the superficial reticular dermis with a fibrotic-to-slight myxoid stroma. The spindle cells in all cases stained strongly for CD34, and only scattered stromal cells stained for Factor XIIIa. Five tested cases were negative for EMA and S100 protein. The digital AFs, fibrokeratomas, and dermatofibromas stained predominately for Factor XIIIa, with no or minimal staining for CD34.
  
  
  CONCLUSIONS
  These findings suggest that a subset of digital fibromas is characterized by a dense cellular proliferation of CD34-positive spindle cells. Awareness of this variant of digital fibroma and its staining pattern is critical in preventing misdiagnosis as dermatofibrosarcoma protuberans, particularly in superficial biopsies.
authors.affiliation: Departments of Dermatology and Pathology, Yale University School of Medicine, New Haven, CT, USA. jennifer.mcniff@yale.edu
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: McNiff
authors.forename: Antonio
authors.initials: A
authors.lastname: Subtil
authors.forename: Shawn E
authors.initials: SE
authors.lastname: Cowper
authors.forename: Rossitza
authors.initials: R
authors.lastname: Lazova
authors.forename: Earl J
authors.initials: EJ
authors.lastname: Glusac
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018952:Antigens, CD34 / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000032:analysis; D018223:Dermatofibrosarcoma / Q000378:metabolism / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D005350:Fibroma / Q000378:metabolism / Q000473:pathology*; D005385:Fingers / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009372:Neoplasms, Connective Tissue / Q000378:metabolism / Q000473:pathology*; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*
chemical_list: D018952:Antigens, CD34; D014408:Biomarkers, Tumor