title: Clinicopathological investigation of four cases of desmoplastic small round cell tumor.
abstract: The purpose of this study was to perform clinicopathological and immunohistochemical analysis and to investigate the Ewing sarcoma gene (EWS)-Wilms' tumor suppressor gene (WT1)fusion within desmoplastic small round cell tumors (DSRCTs). Histology slides and clinical data were reviewed for four patients with DSRCT. A variety of immunohistochemical staining was performed. Fluorescencein situhybridization (FISH) was performed to detect theEWS-WT1fusion transcripts resulting from the chromosomal translocation t(11;22)(p13;q12). The patients consisted of four males aged from 26 to 52 years old (mean, 33.5). In three of these patients, the tumors were situated in the abdominal cavity and the tumor from the other patient was located in the pelvic cavity. The tumors were 8-15 cm in diameter (mean tumor diameter, 13), solid and gray-white, with an appearance of nodosity or sublobes, and hemorrhage or necrosis was observed. Microscopically, the tumors consisted of small round cell nests of unequal size. Hyperplastic and thick fibrous connective tissue surrounding the neoplastic cell nests was present in all cases. The tumor nuclei were hyperchromatic and contained inconspicuous nucleoli with a high level of karyokinesis. Immunohistochemical staining revealed diffuse and strong staining for CK, vimentin, desmin and CAM5.2 in all cases. Certain cases also expressed WT-1, EMA, NSE, CD56, CD99 and CK5/6. Staining was negative for myogenin, MyoD1, calretinin, CD117, CD34, HMB45 and CEA.EWS-WT1fusion transcripts were detected in 3 out of 4 cases, but not in any other tumor types studied as controls using paraffin-embedded tissue by FISH. DSRCT is a highly maligant tumor occuring predominantly in the abdominal or pelvic cavity of young males with multiphenotypic differentiation. Basic morphological features, clinical manifestations and the detection of theEWS-WT1fusion transcript within the tumor aid the recognition and diagnosis of the tumor.
authors.affiliation: State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou 510060, P.R. China ; Department of Pathology, Sun Yat-Sen University Cancer Center, Guangzhou 510060, P.R. China.
authors.forename: Mei
authors.initials: M
authors.lastname: Li
authors.forename: Mu-Yan
authors.initials: MY
authors.lastname: Cai
authors.forename: Jia-Bin
authors.initials: JB
authors.lastname: Lu
authors.forename: Jin-Hui
authors.initials: JH
authors.lastname: Hou
authors.forename: Qiu-Liang
authors.initials: QL
authors.lastname: Wu
authors.forename: Rong-Zhen
authors.initials: RZ
authors.lastname: Luo
keywords: clinicopathological features; desmoplastic small round cell tumor; gene fusion; immunophenotype