Primitive Neuroectodermal Tumor (PNET) of the kidney: a case report

Abstract

Background: A case of Primitive Neuroectodermal Tumor (PNET) of the kidney in a 27-year-old woman is presented. Few cases are reported in the literature with a variable, nonspecific presentation and an aggressive behaviour. In our case, a radical nephrectomy with lymphadenectomy was performed and there was no residual or recurrent tumour at 24-month follow-up.

PNET/Ewing’s sarcoma of the kidney: imaging findings in two cases

“…In adolescents or young adults presenting with a large renal mass, PNET/Ewing's sarcoma may be included in the differential diagnosis. diagnosis include rhabdomyosarcoma, Wilms' tumor, carcinoid tumor, neuroblastoma, lymphoma, desmoplastic small round cell tumor and nephroblastoma (1,3,5). Since no pathognomonic features of PNET/Ewing's sarcoma have been described, it is difficult to preoperatively diagnose this entity (1,4).…”

“…(25%), pulmonary metastases (20%) and liver metastases (14%) (1)(2)(3)(4)(5). One third of patients present with tumor thrombi in the renal vein or inferior vena cava at the time of diagnosis (1).…”

“…It remains unclear whether or not Ewing's sarcoma and PNET are distinct entities since they have similar biologic, pathological and molecular findings (2,5). In the WHO classification they are considered as one entity, presumed to originate from one common precursor (the neural cells in the kidney or the embryonic neural crest cells that migrate into the kidney) probably blocked in a different stage of differentiation (3)(4)(5). PNET shows more mature neural cells than Ewing's sarcoma as demonstrated by the expression of neural immunohistochemical markers such as NSE, vimentin, synaptophysin and S-100 (1).…”

“…Overexpression of the surface membrane CD99 is a suggestive diagnostic clue on immunohistochemistry but the final diagnosis of PNET/Ewing's sarcoma is based on cytogenetic analysis (FISH and PCR) revealing EWS gene rearrangement, including the t(11;22)(q24;q12) translocation (1)(2)(3)5). It remains unclear whether or not Ewing's sarcoma and PNET are distinct entities since they have similar biologic, pathological and molecular findings (2,5). In the WHO classification they are considered as one entity, presumed to originate from one common precursor (the neural cells in the kidney or the embryonic neural crest cells that migrate into the kidney) probably blocked in a different stage of differentiation (3)(4)(5).…”

“…Microscopically PNET/ Ewing's sarcoma is characterized by small round tumor cells with typical Homer-Wright rosette-like growth pattern (2,3,5). Overexpression of the surface membrane CD99 is a suggestive diagnostic clue on immunohistochemistry but the final diagnosis of PNET/Ewing's sarcoma is based on cytogenetic analysis (FISH and PCR) revealing EWS gene rearrangement, including the t(11;22)(q24;q12) translocation (1)(2)(3)5). It remains unclear whether or not Ewing's sarcoma and PNET are distinct entities since they have similar biologic, pathological and molecular findings (2,5).…”