title: Bednar tumor: report of a case with immunohistochemical and ultrastructural study.
abstract: A slowly growing tumor in the right shoulder of a 38-year-old white male, which felt like a superficial cystic mass, was studied. The spindle cells, which represented the main component of the tumor, were arranged in a typical storiform pattern and were positive for CD34 and focally for CD117. The pigmented cells were mostly found at the center of the storiform whorls and were negative for S-100 protein and HMB-45. Ultrastructurally, the tumor consisted predominantly of nondescript mesenchymal spindle cells that resembled fibroblasts. The tumor cells blended into a loosely arranged stromal tissue background. The general appearance of pigmented cells was very similar to the nonpigmented spindle cells. The pigment appeared to be a mature form of melanin granules. The lack of premelanosomes, cell injections, basal lamina, and pinocytotic vesicles was inconsistent with a neural origin/neural differentiation hypothesis for this tumor.
authors.affiliation: Department of Pathology, Indiana University, School of Medicine, Indianapolis, Indiana, USA; and Deaconess Hospital, Oklahoma City, Oklahoma, USA.
authors.forename: In Sook
authors.initials: IS
authors.lastname: Seo
authors.forename: Michael
authors.initials: M
authors.lastname: Goheen
authors.forename: Kyung-Whan
authors.initials: KW
authors.lastname: Min
mesh_terms: D000328:Adult; D018952:Antigens, CD34 / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis; D018223:Dermatofibrosarcoma / Q000737:chemistry / Q000601:surgery / Q000648:ultrastructure*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis; D012782:Shoulder; D012878:Skin Neoplasms / Q000737:chemistry / Q000601:surgery / Q000648:ultrastructure*; D016896:Treatment Outcome
chemical_list: D018952:Antigens, CD34; D014408:Biomarkers, Tumor; D019009:Proto-Oncogene Proteins c-kit