This research seeks to illustrate the efficacy of imaging for the precise identification of tumor masses in individuals with horseshoe kidneys. A patient hospitalized with febrile syndrome without focus undergoes a tomographic scan. So as to characterize the findings in detail, it is decided to perform an MRI with intravenous contrast. Computed tomography in axial sections and sagittal reconstruction shows a voluminous formation in renal topography on the left side with soft tissue density and irregular borders. In the left cardiophrenic angle a rounded image with smooth edges apparently adenopathy is identified. Axial MRI shows a horseshoe kidney with a voluminous formation with lobulated borders and heterogeneous signal in T2 fat sat sequence in the posterior sector of the left kidney. After intravenous contrast administration, peripheral enhancement areas are seen in T1 + C sequence. The diffusion sequence shows peripheral restriction area. The histopathological result in this case was infiltration by high-grade large B-cell lymphoma. After reviewing the literature, we can conclude that the tumors found in horseshoe kidneys present incidence rates very similar to those of the general population. Renal lymphomas are rare entities, although extranodal dissemination usually involves the urinary tract. Despite the definitive diagnosis is histopathological, MRI imaging studies have proved to be useful in this particular case.