Retroperitoneal neoplasms are usually large at the time of presentation due to delay in their diagnosis. Differential diagnosis for retroperitoneal mass includes retroperitoneal sarcoma either liposarcoma, leiomyosarcoma, rhabdomyosarcoma and MFH, retroperitoneal metastasis and retroperitoneal lymphoma. This lesion was biopsied and revealed Non-Hodgkin lymphoma.