title: Bullous malignant melanoma: an unusual differential diagnosis of a hemorrhagic friction blister.
abstract: BACKGROUND
  A 66-year-old woman presented to our outpatient clinic with a 3 x 2.5-cm tense, hemorrhagic-appearing bulla on her forefoot. Histopathology and immunohistochemistry confirmed a transtumoral-transepidermal blister formation within an advanced acrolentiginous malignant melanoma (MM).
  
  
  OBJECTIVE
  To study bullous malignant melanoma.
  
  
  METHODS
  Blistering in MMs represents a rare but clinically important pitfall in clinical differential diagnosis. The blisters are typically due to the disruption of the cohesion between neoplastic cells and keratinocytes, but physical friction may also contribute.
  
  
  RESULTS
  Hemorrhagic blistering is, in many cases, a relatively insignificant finding in which frictional forces are imposed.
  
  
  CONCLUSIONS
  The case reported here underscores that in rare cases MMs, particularly if acrally located, can be complicated by hemorrhagic blistering. Because of the life-threatening consequences, one should be aware of this rare differential diagnosis.
authors.affiliation: Department of Dermatology, University Hospital of Regensburg, Regensburg, Germany. Thomas.Vogt@klinik.uni-renesburg.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Vogt
authors.forename: Stephanie
authors.initials: S
authors.lastname: Brunnberg
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hohenleutner
authors.forename: Michael
authors.initials: M
authors.lastname: Landthaler
mesh_terms: D000368:Aged; D001768:Blister / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008545:Melanoma / Q000473:pathology* / Q000556:secondary; D012878:Skin Neoplasms / Q000473:pathology*