Peripheral neuroectodermal tumors PNET

Although the peripheral neuroectodermal tumor (PNET) and ES were first described, respectively, by Stout in 1918 and Ewing in 1921, it has only recently been established through immunohistochemical and genetic-molecular studies that the two are not only related but also belong to the same family of tumors. ES/PNET may be found in bone, soft tissue, and various parenchymal organs (lung, pancreas, kidney), as well as the head and neck. 

CK, cytokeratin EMA, epithelial membrane antigen LCA, leukocyte common antigen NPC, nasopharyngeal carcinoma ONE, olfactory neuroblastoma ES/PNET, Ewing s sarcoma/peripheral neuroectodermal tumor SNUC, sinonasal undifferentiated carcinoma. 

Many of the tumors of the nasal cavity and paranasal sinuses fall under the category of round cell neoplasms. Among these are olfactory neuroblastoma, sinonasal undifferentiated carcinoma, malignant melanoma, neuroendocrine carcinoma-small cell neuroendocrine carcinoma, malignant lymphoma, extramedullary plasmacytoma, invasive-ectopic pituitary adenoma, rhabdomyosarcoma, and Ewing s sarcoma (ES)-peripheral neuroectodermal tumor (ES/ PNET). But there is also a host of other epithelial lesions that are unique to the sinonasal tract. 

CMV, cytomegalovirus CNS, central nervous system EMA, epithelial membrane antigen GFAP, glial fibrillary acidic protein HV, herpesvirus NF, neurofilament PML, progressive multifocal leukoencephalopathy PNET, primitive neuroectodermal tumor PNS, peripheral nervous system Mw, microwave starting in cold buffer for time noted. 

Peripheral primitive neuroectodermal tumor (pPNET) of the kidney is a very rare entity with high malignant potential and no specific radiological pattern described. The diagnosis is based on histopathology with subsequent demonstration of typical chromosomal translocations of the PNET/ Ewing tumor family (Doerfler et al. 2001 Vicha et al. 2002 Lam et al. 2003). 

The Ewing family of tumors comprises small round cell neoplasms of bone and soft tissue that are, in part, defined by a particular chromosomal aberration [t(ll 22)] and variants thereof. Over the past 15 years, it has become clear that ES and peripheral PNET are part of the same spectrum of neoplastic proliferations. Besides the karyotypic marker just mentioned, both of those tumor types also show neuroectodermal features in tissue culture and similarities in proto-oncogene expression. As classically defined, ES was distinguished from PNET by an absence of pseudorosettes and the lack of ultrastructurally or immunohistochemically detectable neuroectodermal features. However, this diagnostic separation is now considered to be antiquated and has been abandoned. 

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