Differential diagnosis of retroperitoneal masses may become complex and requires careful anamnesis, physical examination and several complementary tests. We present the clinical case of a male patient aged 45 years who was diagnosed with a 4cm paraaortic lesion compatible with neuroendocrine tumor in the abdominal computed tomography (CT) exam. The workup performed with SPECT-CT, somatostatin receptors scintigraphy, MIBG scintigraphy, 24-hour urine total and fractionated catecholamines and 24-hour urine 5-OH indoleacetic did not confirm the first diagnostic impression. Finally, the lesion was biopsied and presence of micro-organisms was revealed. Further exams confirmed schistosomiasis as the cause of the paraaortic lesion. Histological diagnosis can be helpful with regard to the differential diagnosis of retroperitoneal masses.