Desmoplastic small round cell tumor

Desmoplastic small round cell tumor variants of polyphenotypic small round cell tumors are generally negative for CD99. 

The small round cell tumors of soft tissue (Fig. 4.9 see Table 4.4) compose a heterogeneous group of neoplasms that predominate in childhood and adolescence and share similar morphologic features. Rhabdomyosarcoma, PNET/ES, and lymphoma/leukemia are the prototypic members of this group. Another entity that may be confused with PNET is the intra-abdominal desmoplastic small round cell tumor. 

The extent of staining with myogenin is also helpful in subclassification, because the alveolar variant of rhabdomyosarcoma usually shows extensive labeling in nearly all neoplastic cells, whereas E-RMS shows more heterogeneous reactivity. Other small round cell tumors lack those determinants, with the notable exception of intra-abdominal desmoplastic small round cell tumors, which are usually positive for desmin, but not for myogenin. 

The term polyphenotypic small round cell tumor seems most appropriate to describe the general attributes of these lesions. The desmoplastic small round cell tumor (DSRCT) is the best-recognized representative of this group. It is characterized by an EWS/WTl chimeric transcript, and is a morphologically distinctive neoplasm that is characterized by reactive fibrosis surrounding discrete nests of tumor cells (Fig. 4.15). DSRCT has a relatively complicated immunoprofile. 

FIGURE 4.15 Desmoplastic small round cell tumor is a distinctive small round cell malignancy that manifests a densely fibrogenic stroma. 

Ordi J, de Alava E, Tome A, et al. Intraabdominal desmoplastic small round-cell tumor with EWS/ERG fusion transcripts. Am J Surg Pathol. 1998 22 1026-1032. 

Gerald WL, Ladanyi M, de Alava E, et al. Clinical, pathologic, and molecular spectrum of tumors associated with t(ll 22) (pl3]2) Desmoplastic small round-cell tumor and its variants. J Clin Oncol. 1998 16 3028-3036. 

Desmoplastic small round cell tumor Young adults, often adolescent boys. Abdomen and pelvis, peritoneal implants. Round/oval cells in desmoplastic stroma in classic cases, other cases with variable morphology Vimentin+, cytokeratin+, EMA+, desmin+, WT1 + RT-PCR for EWS-WT1... 

Worthy of note is an immunohistochemical marker, NB84, that is a monoclonal antibody raised to neuroblastoma cells.Miettinen and coworkers studied 22 cases of undifferentiated neuroblastomas and 83 cases of differentiated neuroblastomas (total of 105 cases) and found that 95.5% of the former and 100% of the latter were positive for NB84. In addition, 4 of 5 (80%) of ES-PNETs and 3 of 3 (100%) of desmoplastic small, round cell tumors also showed positive staining. In contrast, 7 of 39 (17.9%) of ES and 1 of... 

Desmoplatic small round cell tumors occur primarily in the abdominal cavity.The neoplasms characteristically show immunostaining for desmin (a dotlike pattern), WTl, keratin, neuron-specific enolase, CD99, and actin. They also show the EWS-WTl gene fusion transcript. A desmoplastic, small, round cell tumor was reported primary in the lung by Syed and coworkers.Ultrastructurally, this tumor showed intracytoplasmic whorls of intermediate filaments, presumably desmin. A desmoplastic, small, round cell tumor was also reported as a primary neoplasm in the pleura. 

Mesothelin is a 40-kD glycoprotein of unknown function that is strongly expressed in mesothelial cells, ovarian serous cells, and pancreatic-bile duct cells. Using monoclonal antibody 5B2, Ordonez found it to immu-nostain normal mesothelial cells, mesotheliomas, non-mucinous ovarian carcinomas, and occasionally other neoplasms. Ordonez concluded that mesothelin staining could be used to diagnose mesotheliomas, although it was expressed in 14 of 14 ovarian carcinomas, 12 of 14 pancreatic ductal adenocarcinomas, 7 of 12 desmoplastic small round cell tumors, and 9 of 9 synovial sarcomas. Therefore, this antibody should be interpreted carefully. 

Lae ME, Roche PC, Jin L, et al. Desmoplastic small round cell tumor A clinicopathologic, immunohistochemical and molecular study of 32 tumots. Am J Surg Pathol. 2002 26 823-835. 

Ostoros G, Orosz Z, Kovacs G, et al. Desmoplastic small round cell tumor of the pleuta A case teport with unusual follow-up. Lung Cancer. 2002 36 333-336. 

An antibody to the car boxy-terminal (C-terminal) region of the WT gene (WTl) is useful in recognition of desmoplastic small round cell tumor. DSRCT shows strong nuclear staining with a C-terminal WTl antibody WT and RMS can also show nuclear reactivity for WTl.37,47,48 have observed occasional examples of... 

Desmoplastic small round cell tumor SRCs in nests with prominent stromal desmoplasia, central necrosis, variable cystic degeneration, and epithelial differentiation. Polyphenotypic cytokeratins, epithelial membrane antigen, vimentin, desmin, WT1 (C-terminus), CD99. t(11 22)(p13 q12)with EWS/WTl fusion. 

FIGURE 17.19 Desmoplastic small round cell tumor displays round and polygonal tumor cells arranged in geographic nests separated by a fibrous stroma (hematox3 in-eosin, x100). 

VImentIn Keratin EMA Desmin WT1 NSE CD99 figure 17.20 An Immunohistogram of desmoplastic small round cell tumor. 

FIGURE 17.21 Vimentin displays diffuse cytoplasmic reactivity in desmoplastic small round cell tumor (immunoperoxidase, x400). 

Zhang PJ, Goldblum JR, Pawel BR, et al. Immunophenotype of desmoplastic small round cell tumors as detected in cases with EWS-WTl gene fusion product. Mod Pathol. 2003 16 229-235. 

Hill DA, Pfeifer JD, Marley EF, et al. WTl staining reliably differentiates desmoplastic small round cell tumor from Ewing sarcoma/primitive neuroectodermal tumor. An immunohistochemical and molecular diagnostic study. Am J Clin Pathol. 2000 114 345-353. 

Barnoud R, Sabourin JG, Pasquier D, et al. Immunohistochemical expression of WTl by desmoplastic small round cell tumor a comparative study with other small round cell tumors. Am J Surg Pathol. 2000 24 830-836. 

Livaditi E, Mavridis G, Soutis M, et al. Diffuse intraabdominal desmoplastic small round cell tumor a ten-year experience. Eur J Pediatr Surg. 2006 16 423-427. 

Saab R, Khoury JD, Krasin M, et al. Desmoplastic small round cell tumor in childhood the St. Jude Ghildren s Research Hospital experience. Pediatr Blood Cancer. 2007 49 274-279. 

Collardeau-Frachon S, Ranchere-Vince D, Delattre O, et al. Primary desmoplastic small round cell tumor of the kidney a case tepott in a 14-year-old girl with molecular confirmation. Pediatr Dev Pathol. 2007 10 320-324. 

Zhang J, Dalton J, Ftrller C. Epithelial marker-negative desmoplastic small round cell tumor with atypical morphology definitive classification by fluorescence in situ hybridization. Arch Pathol Lab Med. 2007 131 646-649. 

Barnoud R, Delattre O, Peoc h M, et al. Desmoplastic small round cell tumor RT-PCR analysis and immunohistochemical detection of the Wilms tumor gene WTl. Pathol Res Pract. 1998 194 693-700. 

Gerald WL, Rosai J, Ladanyi M. Gharacterization of the genomic breakpoint and chimeric transcripts in the EWS-WTl gene fusion of desmoplastic small round cell tumor. Proc Nall Acad SciUSA. 1995 92 1028-1032. 

Ladanyi M, Gerald W. Fusion of the EWS and WTl genes in the desmoplastic small round cell tumor. Cancer Res. 1994 54 2837-2840. 

Leuschner I, Radig K, Harms D. Desmoplastic small round cell tumor. Semin Diagn Pathol. 1996 13 204-212. 

Froberg K, Brown RE, Gaylord H, Manivel G. Intra-abdominal desmoplastic small round cell tumor immunohistochemical evidence for up-regulation of autocrine and paracrine growth factors. Ann Clin Lab Sci. 1998 28 386-393. 

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