title: Sclerotic fibroma-like dermatofibroma: an uncommon distinctive variant of dermatofibroma.
abstract: Dermatofibroma (DF) is a common benign cutaneous tumor with many variants based on alterations in the morphology and composition of its diverse elements. One very infrequent type is sclerotic fibroma-like DF (SF-DF). We report 7 new cases of SF-DF. In addition, their main clinicopathological and immunohistochemical features were compared with 14 unselected common DFs and with 3 sclerotic fibromas (SFs). Microscopically, the 7 cases of SF-DFs showed an unencapsulated, well-circumscribed, hypocellular central nodule with thick collagen bundles arranged in a storiform pattern with prominent clefts. The overlying epidermis was attenuated. The periphery of this nodule was more cellular with histopathologic features of common DF. The 7 SF-DFs patients were 4 women and 3 men with a mean (+/-SD) age of 44.8 (+/-15.5) years. These 7 patients were younger than those suffering from SFs [71.0 (+/-17.3) years; (p=0.04)] and older than those presenting common DFs [30.5 (+/-12.3) years; (p=0.03)]. Immunohistochemically, spindle cells in all 7 SF-DFs were negative for CD34 and CD99. On the contrary, the 3 cases of SF were positive for CD34 and CD99. All of the common DFs were negative for CD34 and only 4 (28.6%) of them were positive for CD99. In conclusion, SF-DF is an uncommon variant of DF with similar clinicopathological and immunohistochemical features. SF-DF shares certain histopathologic features with SF but they are immunophenotypically different. Therefore, both entities should be differentiated.
authors.affiliation: Department of Anatomical Pathology, Marques de Valdecilla University Hospital, Medical Faculty, University of Cantabria, Avda. Valdecilla 1, Santander, Spain.
authors.forename: M C
authors.initials: MC
authors.lastname: González-Vela
authors.forename: J F
authors.initials: JF
authors.lastname: Val-Bernal
authors.forename: M
authors.initials: M
authors.lastname: Martino
authors.forename: M A
authors.initials: MA
authors.lastname: González-López
authors.forename: E
authors.initials: E
authors.lastname: García-Alberdi
authors.forename: S
authors.initials: S
authors.lastname: Hermana
mesh_terms: D000071443:12E7 Antigen; D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34 / Q000032:analysis; D015815:Cell Adhesion Molecules / Q000032:analysis; D005260:Female; D005350:Fibroma / Q000473:pathology*; D018219:Histiocytoma, Benign Fibrous / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D012598:Sclerosis; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*; D014746:Vimentin / Q000032:analysis
chemical_list: D000071443:12E7 Antigen; D015703:Antigens, CD; D018952:Antigens, CD34; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules; D014746:Vimentin