title: De novo malignant solitary fibrous tumor of the kidney.
abstract: The kidney is a relatively infrequent site for solitary fibrous tumor (SFT). Among the previously reported cases, only two cases of malignant renal SFT developing via dedifferentiation from a pre-existing benign SFT have been reported. Here we reported a case of de novo malignant renal SFT clinically diagnosed as renal cell carcinoma in a 50-year-old woman. The tumor was circumscribed but unencapsulated and showed obvious hemorrhagic necrosis. Microscopically, the tumor was composed of patternless sheets of alternating hypercellular and hypocellular areas of spindle cells displaying mild to moderate nuclear atypia, frequent mitoses up to 8 per 10 high power fields, and a 20% Ki-67 proliferative index. Immunohistochemical studies revealed reactivity for CD34, CD99 and vimentin, with no staining for all other markers, confirming the diagnosis of SFT. No areas of dedifferentiation were seen after extensive sampling. Based on the pathologic and immunohistochemical features, a diagnosis of de novo malignant renal SFT was warranted. Our report expands the spectrum of malignant progression in renal SFTs. Even though this patient has been disease-free for 30 months, long-term follow-up is still mandatory.
authors.affiliation: Department of Pathology, Chang Gung Memorial Hospital, Keelung, Taiwan.
authors.forename: Tsan-Yu
authors.initials: TY
authors.lastname: Hsieh
authors.forename: Yi-Che
authors.initials: YC
authors.lastname: ChangChien
authors.forename: Wen-Hsiang
authors.initials: WH
authors.lastname: Chen
authors.forename: Siu-Chung
authors.initials: SC
authors.lastname: Chen
authors.forename: Liang-Che
authors.initials: LC
authors.lastname: Chang
authors.forename: Cheng-Cheng
authors.initials: CC
authors.lastname: Hwang
authors.forename: Hui-Ping
authors.initials: HP
authors.lastname: Chein
authors.forename: Jim-Ray
authors.initials: JR
authors.lastname: Chen
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D002292:Carcinoma, Renal Cell / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D009392:Nephrectomy; D054364:Solitary Fibrous Tumors / Q000378:metabolism / Q000473:pathology* / Q000601:surgery
chemical_list: D014408:Biomarkers, Tumor