title: High proliferative activity excludes dermatofibroma: report of the utility of MIB-1 in the differential diagnosis of selected fibrohistiocytic tumors.
abstract: BACKGROUND
  Dermatofibroma is a benign fibrohistiocytic tumor composed of a mixture of fibroblastic and histiocytic cells. The diagnosis of this tumor is generally uncomplicated; however, rare variants may be difficult to distinguish from malignant fibrohistiocytic tumors. Deep penetrating dermatofibroma may be difficult to distinguish from dermatofibrosarcoma protuberans, and pseudosarcomatous dermatofibroma and dermatofibroma with monster giant cells share morphologic similarities with malignant fibrous histiocytoma and atypical fibroxanthoma.
  
  
  OBJECTIVE
  To find an immunohistochemical marker or markers that differentiate between fibrohistiocytic lesions of skin.
  
  
  METHODS
  We evaluated the immunophenotypic characteristics of 83 fibrohistiocytic tumors (36 typical dermatofibromas, 16 cases of dermatofibrosarcoma protuberans, 16 malignant fibrous histiocytomas, and 15 atypical fibroxanthomas) using antibodies against MIB-1 (Ki-67), factor XIIIa, CD34 (HPCA-1), HHF35 (muscle-specific actin), 1A4 (smooth muscle actin), cytokeratin (AE1/AE3, CAM 5.2, and 34betaE12), S100 protein, and desmin.
  
  
  RESULTS
  A high proliferative index detected by MIB-1 staining excluded the possibility of dermatofibroma and was diagnostically useful in separating this entity from dermatofibrosarcoma protuberans, malignant fibrous histiocytoma, and atypical fibroxanthoma. A low proliferative index, however, could not differentiate dermatofibroma from dermatofibrosarcoma protuberans. Factor XIIIa reactivity was not helpful for the diagnosis of dermatofibroma, whereas CD34 reactivity was statistically significant in the diagnosis of dermatofibrosarcoma protuberans. The sensitivity of these 2 markers is low and therefore of questionable practical diagnostic value.
  
  
  CONCLUSIONS
  Evaluation of the proliferative index may further assist in distinguishing dermatofibroma from dermatofibrosarcoma protuberans, atypical fibroxanthoma, and malignant fibrous histiocytoma.
authors.affiliation: Department of Pathology, University of Miami/Jackson Memorial Medical Center, Miami, FL, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hanly
authors.forename: Mercè
authors.initials: M
authors.lastname: Jordà
authors.forename: George W
authors.initials: GW
authors.lastname: Elgart
authors.forename: Evangelos
authors.initials: E
authors.lastname: Badiavas
authors.forename: Mehdi
authors.initials: M
authors.lastname: Nassiri
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Nadji
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D001706:Biopsy; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation; D018223:Dermatofibrosarcoma / Q000473:pathology; D003937:Diagnosis, Differential; D019084:Fluorescent Antibody Technique, Indirect; D018219:Histiocytoma, Benign Fibrous / Q000145:classification / Q000378:metabolism / Q000473:pathology*; D051677:Histiocytoma, Malignant Fibrous / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D019394:Ki-67 Antigen / Q000378:metabolism*; D012878:Skin Neoplasms / Q000145:classification / Q000378:metabolism / Q000473:pathology*; D014973:Xanthomatosis / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen