A case report on retroperitoneal PNET/EWS

Abstract

Primitive neuroectodermal tumor (PNET) and Ewing's sarcoma (EWS) are small round cell tumors occurring mainly in children and adolescents, rarely in adults. It can occur in multiple tissues and organs including kidney, adrenal, bladder, liver, small intestine, colon and rectum, with a preferred location within the chest area, in the limbs and around the spine, but with rare cases of abdominal, pelvic or retroperitoneal. Here we present a case of the retroperitoneal PENT/EWS in a 38-year-old man and we discuss the clinical features, histopathological characteristics, diagnosis, treatment and prognosis.

Retroperitoneal blue cell round tumor (Ewing sarcoma in a 35 years old male)- case report

“…The better known of the Ewing sarcoma family is Ewing's sarcoma (EWS)/Peripheral NeuroEctodermal Tumor (PNET). It is a malignant small blue round cell tumor with variable degree of neuroectodermal differentiation [4] , [5] . Most common site of Ewing sarcoma is the bone and hence the so called skeletal EWS predominantly occurring in pediatric age group, while the extra- skeletal (extraosseous) EWS is very rare.…”

“…The cytoplasm is usually pale blue with punched out valocules corresponding to glycogen deposits which will be demonstrated by the acid Schiff stainig – but yet the large amount of intracellular glycogen is not specific for the ES EWS [11] . Homer -Wright rosettes may or may not be present depending on the degree of differentiation [12] . As the histopathological appearance of small round blue cells has an ever expanding list of differentials in case of retroperitoneal EWS depending on the cell lineage such as: 1/Epithelial tumors including small cell Carcinomas, 2/Mesenchymal tumors as Desmoplastic Small Round Cell Tumors (DSRCTs) and Rhabdomyosarcomas, 3/ Malignant melanoma, and Lymphoma, immunohistochemistry is often mandatory to reach the final diagnosis.…”

“…Many studies have confirmed that CD99 or MIC which shows membrane positivity was helpful in distinguishing the EWS/PNET group from other MSRCTs [11] , [13] . Vimentin, NSE and S-100 are also frequently expressed [4] , and negative for Desmin and CK [7] .…”

“… They usully present as large masses at time of the disgnosis so they do not produce symptoms unitil they grow large to compress on adjacent organs Multimodality treatment is recommended in terms of surgical resection, chemotherapy and high dose radiotherapy. Early diagnosis of such rare tumor will help targeting it at early stage [1] , [2] , [3] , [4] …”