Introduction Primitive neuroectodermal tumors PNETs are
Primitive neuroectodermal tumors (PNETs) are malignant, small round cell tumors of neural crest origin which typically arises from bone or soft tissue in the trunk/axial skeleton/paraspinal regions in adolescents and young adults and comprises of <1% of all sarcomas. Incidence of extraosseous PNET involving genitourinary system such as kidney, bladder, epididymis, and prostate is extremely rare.1, 2 The diagnosis of renal PNET is based on histomorphology and immunohistochemistry, supported by cytogenetic analysis, therefore preoperative diagnosis is challenging. Multidisciplinary treatment strategies including surgery, adjuvant chemotherapy, and radiotherapy are favored. Owing to the high aggressiveness, presence of >50% cases with local recurrence and metastasis at the time of presentation lead to overall poor prognosis of renal PNET (rPNET). Ewing sarcoma (ES) and PNET represent morphologic spectrum of same disease process; however, cases with, Flexnere Wintersteiner or Homer Wright rosettes were initially diagnosed as PNET. Genetically, this tumor is characterized by recurrent chromosomal translocations of EWSR1 gene on chromosome 22, i.e. t (21;22) (q24;q12) resulting in fusion of EWSR1 (22q12) and Friend leukemia virus integration 1 (FLI1 genes 11q24) in 90–95% of rPNET/EWS. Here we are discussing the clinical, histopathological, immunohistochemical findings and treatment outcomes of rPNET in a young male with preoperative diagnosis of clear cell type of renal cell carcinoma (RCC).
Case report A 35-year-old male patient presented with left lower flank pain radiating to back, painless hematuria, dysuria, and weight loss and managed initially as a case of left ureteric colic. Ultrasonography of abdomen revealed bilateral renal calculus with a mass lesion at upper pole of left kidney. Contrast enhanced computed tomography (CECT) showed a hypodense lesion measuring 80 × 67 mm in upper pole of left kidney with variegated post nos inhibitor enhancement and extension into the left renal vein; a possibility of RCC with right non-obstructive renal calculi was considered. Hematological and biochemical profiles were within normal limits. The patient underwent left robotic radical nephrectomy. Gross examination of the specimen showed a lobulated, variegated tumor measuring 9.1 × 5.8 × 4 cms occupying the upper pole. Renal pelvis and left renal vein appears involved on gross. Histopathological examination revealed a tumor composed of sheets, cords of small, round, and monomorphic cells having high N:C ratio, poorly defined cytoplasmic membrane, hyperchromatic nuclei, and inconspicuous nucleoli (Fig. 1). Immunohistochemical analysis showed positivity for vimentin, CD 99, WT1, and Ki67 80–90%, while negativity for CD45, pancytokeratin, synaptophysin, and chromogranin (Table 1). A diagnosis of rPNET with involvement of renal sinus, perirenal fat, left renal vein, and two positive regional lymph nodes was confirmed (pT3aN1My: stage III). After nephrectomy, the patient started, from 29 May 2017, VAC/IE regiment adjuvant chemotherapy comprised of vincristine, doxorubicin, cyclophosphamide, ifosfamide, and etoposide and has received 11 cycles till 16 Jan 2018. On follow-up, our patient is disease-free till now.
Conflicts of interest
Introduction To maximize the benefits and minimize the toxicity of an oncotherapy, targeted therapy has emerged as one of the major modalities for cancer control, with impressive results obtained for a number of cancers. These targets are either surface markers such as human epithelial receptor 2 (HER2) (targeted by trastuzumab) . or internal identifiers such as BRAF V600E mutation (targeted by vemurafenib)  and EML4-ALK fusion (targeted by crizobinib) . It is estimated that gene fusions are responsible for 20% of global cancer morbidities . Increasing evidences have elucidated many crucial oncogenic functionalities of fusion genes, from fusion generation mechanisms to pathological consequences, against which targeted therapies have demonstrated tremendous efficacies in clinics.