title: Solitary fibrous tumor involving the renal capsule.
abstract: Solitary fibrous tumors are spindle-cell neoplasms that originally were described in the pleura but that can occur in a large variety of sites. We report a well-circumscribed tumor, apparently involving the renal capsule, clinically thought to be a renal-cell carcinoma or oncocytoma. It was composed of bland spindle-shaped cells with a patchy lymphoplasmacytic infiltrate, suggesting sarcomatoid renal-cell carcinoma, inflammatory myofibroblastic tumor, or solitary fibrous tumor; however, immunohistochemical stains were negative for keratin, alpha-smooth-muscle actin, and desmin but strongly positive for CD34. Ultrastructural examination revealed fibroblast-like cells without myofibroblastic or epithelial differentiation. The combined findings favor a diagnosis of a solitary fibrous tumor involving the renal capsule. To our knowledge, this lesion has not been reported in this location.
authors.affiliation: Department of Pathology, University of California, San Francisco 94143-0102, USA.
authors.forename: A B
authors.initials: AB
authors.lastname: Gelb
authors.forename: M L
authors.initials: ML
authors.lastname: Simmons
authors.forename: N
authors.initials: N
authors.lastname: Weidner
mesh_terms: D018952:Antigens, CD34 / Q000032:analysis; D002292:Carcinoma, Renal Cell / Q000473:pathology; D002467:Cell Nucleus / Q000648:ultrastructure; D003937:Diagnosis, Differential; D005260:Female; D005347:Fibroblasts / Q000648:ultrastructure; D005354:Fibrosarcoma / Q000473:pathology; D006104:Granuloma, Plasma Cell / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007680:Kidney Neoplasms / Q000737:chemistry / Q000473:pathology*; D008854:Microscopy, Electron; D008875:Middle Aged; D018218:Neoplasms, Fibrous Tissue / Q000737:chemistry / Q000473:pathology*; D015388:Organelles / Q000648:ultrastructure; D009418:S100 Proteins / Q000032:analysis; D014057:Tomography, X-Ray Computed
chemical_list: D018952:Antigens, CD34; D009418:S100 Proteins