title: Desmoplastic small cell tumor of soft tissue: molecular variant of EWS-WT1 chimeric fusion.
abstract: A 7-year-old girl was hospitalized because of a tumorous mass in her left periorbital region. The tumor was removed by local excision. The soft-part tumor recurred in the parotid gland region 4 months later, and a second recurrence was noted on the left side of the neck 3 years and 3 months thereafter. The patient had not received chemotherapy or local irradiation. Histological and immunohistochemical examinations of the recurrent masses revealed morphological characteristics of small cell proliferation with desmoplastic stroma that were similar to those of the initial tumor. The cellular components showed immunoreactivity for desmin, cytokeratin, vimentin, and epithelial membrane antigen in part, but the cells were negative for myogenin, CD99, and neuron-specific enolase. These findings suggested a diagnosis of desmoplastic small cell tumor, despite its extra-abdominal location. The histological diagnosis was confirmed by reverse transcriptase polymerase chain reaction, which demonstrated an EWS-WT1 chimeric fusion gene. An in-frame fusion of EWS exon 9 and WT1 exon 8 was subsequently identified by cloning and sequencing. The chimeric fusion gene might be related to the tissue-specific phenotype of desmoplastic small cell tumors, although further investigation of this speculation is necessary.
authors.affiliation: Department of Pathology, Shizuoka Children's Hospital, Shizuoka, Japan. mhamasan@sch.pref.shizuoka.jp
authors.forename: Minoru
authors.initials: M
authors.lastname: Hamazaki
authors.forename: Hajime
authors.initials: H
authors.lastname: Okita
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Hata
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Shimizu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Aoki
authors.forename: Taemi
authors.initials: T
authors.lastname: Nara
mesh_terms: D002648:Child; D003893:Desmin / Q000378:metabolism*; D003937:Diagnosis, Differential; D005260:Female; D006258:Head and Neck Neoplasms / Q000235:genetics* / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008228:Lymphoma, Non-Hodgkin / Q000473:pathology; D046529:Microscopy, Electron, Transmission; D018396:Mucin-1 / Q000378:metabolism; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012208:Rhabdomyosarcoma / Q000473:pathology; D012512:Sarcoma, Ewing / Q000473:pathology; D012983:Soft Tissue Neoplasms / Q000235:genetics* / Q000473:pathology*; D014746:Vimentin / Q000378:metabolism
chemical_list: D003893:Desmin; C106032:EWS1-WT1 fusion protein, human; D018396:Mucin-1; D015514:Oncogene Proteins, Fusion; D014746:Vimentin