title: Keloidal atypical fibroxanthoma: a case series.
abstract: BACKGROUND
  Keloidal atypical fibroxanthoma (AFX) is a rare variant of AFX with thick bands of hyalinized collagen. The identification of keloidal collagen associated with fibrohistiocytic cells may erroneously lead to the diagnosis of keloidal dermatofibroma. Although AFX is a pleomorphic cutaneous tumor typically associated with a good prognosis, occasional reports of metastatic AFX highlight the importance of accurate identification.
  
  
  METHODS
  A total of nine cases of an unusual variant of AFX with keloidal tumoral sclerosis were collected and examined. The cases were stained with antibodies directed against S100, cytokeratin, CD68 and CD31.
  
  
  RESULTS
  Histopathological examination revealed pleomorphic cells trapped within hyalinized keloidal collagen bands. In several cases, the keloidal collagen also formed ring-shaped structures surrounding CD31-positive vascular structures. Pleomorphic cells were negative for S100 protein and keratin, but consistently labeled with antibodies directed against CD68.
  
  
  CONCLUSIONS
  The diagnosis of keloidal AFX requires the exclusion of other malignant and benign lesions with keloidal or sclerotic collagen. Awareness of the rare variant of keloidal AFX may avoid a diagnostic pitfall leading to an erroneous diagnosis, particularly in small biopsies. The finding of sclerotic collagen preferentially deposited around vessels is an interesting and poorly understood phenomenon.
authors.affiliation: Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520-8059, USA.
authors.forename: Jinah
authors.initials: J
authors.lastname: Kim
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: McNiff
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D018219:Histiocytoma, Benign Fibrous / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D007627:Keloid / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D019408:Platelet Endothelial Cell Adhesion Molecule-1; C067980:CD68 antigen, human; D000097382:CD68 Molecule