title: Multinucleate cell angiohistiocytoma: a fibrohistiocytic proliferation with increased mast cell numbers and vascular hyperplasia.
abstract: BACKGROUND
  Multinucleate cell angiohistiocytoma (MCAH) is an uncommon lesion clinically characterized by multiple papules usually located on the face and acral regions of elderly women. Histopathologically, MCAH is characterized by dermal vascular hyperplasia associated with increased number of factor XIIIa-positive fibrohistiocytic cells and multinucleate cells with scalloped borders.
  
  
  METHODS
  We report the clinical, histopathological and immunohistochemical features of three cases of MCAH, with ulstrastructural study in one of them. The patients were a woman and two men of 56, 40 and 70 years of age, respectively. They all had multiple dull-red papules, which had appeared over several years and were located on the face, the trunk and the dorsa of the hands, respectively.
  
  
  RESULTS
  The reticular dermis presented a fibrohistiocytic proliferation of factor XIIIa-positive cells, with abundant bizarre multinucleate cells and vascular hyperplasia. Increased mast cell numbers were seen in all cases, often in apposition to multinucleate cells.
  
  
  CONCLUSIONS
  Histopathological differential diagnosis of MCAH includes mainly angiofibromas and dermatofibromas, even though vascular hyperplasia can be prominent and has led to many authors to classify MCAH among vascular tumors. Bizarre multinucleate cells can be found in reactive, neoplastic and inflammatory lesions in many sites of the body, and mast cells can play a role in their morphogenesis.
authors.affiliation: Department of Dermatology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. lpuig@hsp.santpau.es
authors.forename: Lluís
authors.initials: L
authors.lastname: Puig
authors.forename: María-Teresa
authors.initials: MT
authors.lastname: Fernández-Figueras
authors.forename: Isabel
authors.initials: I
authors.lastname: Bielsa
authors.forename: Betlem
authors.initials: B
authors.lastname: Lloveras
authors.forename: Agustín
authors.initials: A
authors.lastname: Alomar
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor; D001808:Blood Vessels / Q000473:pathology; D002452:Cell Count; D002467:Cell Nucleus / Q000473:pathology; D020405:Dermis / Q000098:blood supply; D026122:Factor XIIIa / Q000032:analysis; D005260:Female; D015726:Giant Cells / Q000648:ultrastructure; D018219:Histiocytoma, Benign Fibrous / Q000098:blood supply / Q000737:chemistry / Q000473:pathology*; D006801:Humans; D006965:Hyperplasia; D008297:Male; D008407:Mast Cells / Q000737:chemistry / Q000473:pathology*; D008875:Middle Aged; D012878:Skin Neoplasms / Q000098:blood supply / Q000737:chemistry / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D026122:Factor XIIIa