Renal embryonal nephroma exhibiting malignant features in a Dutch rabbit (Oryctolagus cuniculus)

Abstract Background Benign embryonal nephromas have been documented in rabbits. However, only one case of nephroblastoma with concurrent metastasis (pulmonary), a post-mortem incidental finding, has been published. Case presentation A three-year-old neutered male Dutch rabbit (Oryctolagus cuniculus) was referred for assessment of a firm mass located in the mid-dorsal abdomen. Abdominal ultrasonography confirmed a large soft tissue mass of suspected renal origin. A left-sided nephrectomy was performed via a ventral midline approach. Multiple white macular lesions, hyperemia, and petechiae were observed in the mesenteric fat surrounding the spleen. Histopathological examination of the abnormal kidney and the mesenteric fat revealed microscopic findings consistent with an embryonal nephroma exhibiting distinct features of malignancy. At 6- and 12-months post-surgery, ultrasonographic evidence of tumor recurrence was not observed. Conclusion and case relevance This is the first report of successful treatment of an embryonal nephroma showing malignant behavior and metastasis to the surrounding adipose tissue with a minimum post-operative survival time of 12 months and no ultrasonographic evidence of local recurrence.