Rhabdomyosarcomas desmoplastic small round cell tumor

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. 

T-cell lymphoma, ALCL, AML, GIST, breast metaplastic carcinoma, ovarian sex cord stromal tumors, synovial sarcoma, Merkel cell carcinoma, endocrine and neuroendocrine tumors, desmoplastic small round cell tumor, melanoma, nephroblastoma, ependymoma, mesenchymal chondrosarcoma, extrarenal malignant rhabdoid tumor, rhabdomyosarcoma, meningeal... 

Neuroblastomas are small, round, blue cell tumors that may arise in the adrenal gland and a variety of extra-adrenal sites. The differential diagnosis is wide and includes rhabdomyosarcoma, Ewing s sarcoma-primitive neuroectodermal tumor (ES-PNET), medulloblastoma, small cell osteosarcoma, lymphoblastic lymphoma, blastematous Wilms tumor, and small cell desmoplastic tumor. Numerous markers have been used for the diagnosis of neuroblastomas including NE markers, cytoskeletal proteins, catecholamine-synthesizing enzymes, and neuroblastoma-"specific antibodies (Eig. 

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