Introduction : The peripheral primitive neuroectodermal tumor(PNET) is a malignant small round cell neoplasm of neural origin that arises outside the brain, spinal cord and sympathetic nervous system.This tumor most often arises in the chest wall and paraspinal region; however, less common origins have been described in literature including bones, limbs and genitourinary tract . We here report one case of primitive neuroectodermal tumor of kidney in our Institution.

Case Report: A 23 year old male presented with complaints of pain abdomen and fever since a week. There was no history of haematuria, vomiting or burning micturition. On examination, right renal angle tenderness was present, a vague mass was palpable in right lumbar region. Ultrasonography showed lobulated hypoechoic lesion in lower pole of right kidney. CT scan revealed, well defined heterogeneously enhancing iso to hypodense lesion measuring 5x4.6x4.6 cm in lower pole of right kidney. On post contrast study, lesion shows heterogenous enhancement with multiple non enhancing areas within-s/o necrosis. Patient underwent nephrectomy Histopathology  revealed round cell tumor with capsular , peri nephric fat  and lymphovascular invasion. Renal sinus showed tumor infiltration. Immunohistochemically  neuron specific marker was identified.

Conclusion: PNET is extremely rare in the kidney, but because of its imaging characteristics, when a large necrotic and haemorrhagic renal mass is found in within the tumor are less likely to indicate this diagnosis. Exact diagnosis of pnet of kidney should be done using  immunohistochemical markers.