title: Deep penetrating dermatofibroma.
abstract: BACKGROUND
  Deep penetrating dermatofibroma is an unusual and histologically distinctive form of dermatofibroma that usually occurs on the lower extremities of adults.
  
  
  OBJECTIVE
  The dermatologic surgeon and pathologist should be aware of this entity to prevent excessive treatment of a benign condition.
  
  
  METHODS
  We are reporting a case of deep penetrating dermatofibroma with the results of histologic examination and immunohistochemical studies.
  
  
  RESULTS
  The neoplasm consisted of a fibrohistiocytic tumor penetrating into the subcutis accompanied by scalloped extensions along the septae. Immunohistochemical stains were positive for Factor XIIIa and negative for CD34.
  
  
  CONCLUSIONS
  Recognition of the histologic pattern is important in distinguishing deep penetrating dermatofibroma from dermatofibrosarcoma protuberans.
authors.affiliation: Department of Dermatology, University of Arkansas for Medical Sciences, Little Rock 72205, USA.
authors.forename: C L
authors.initials: CL
authors.lastname: Laughlin
authors.forename: P R
authors.initials: PR
authors.lastname: Carrington
mesh_terms: D018223:Dermatofibrosarcoma / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D018219:Histiocytoma, Benign Fibrous / Q000473:pathology / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D007866:Leg; D008875:Middle Aged; D012867:Skin / Q000473:pathology; D012878:Skin Neoplasms / Q000473:pathology / Q000601:surgery