Nefroma quístico: tumor benigno de apariencia maligna

Cystic nephroma is a renal lesion belonging to the group of mixed epithelial and mesenchymal tumors, together with other infrequent tumors, such as synovial sarcoma and mixed epithelial and stromal tumor. It is considered one of the rarest renal tumors, and up to the present date, fewer than 250 cases have been reported in the international medical literature.

A 24-year-old homosexual man with a smoking index of 2 had a past history of condylomatous perianal lesion resection. He presented with left renal colic that was medically managed. Physical exploration revealed left costovertebral angle percussion. Urinalysis reported a pH of 5.5, blood ++, and a scant quantity of yeasts. The patient was HIV negative. Tomography scan identified an incidental left renal lesion with a Bosniak III multicystic component (25.3 mm × 28.2 mm). Magnetic resonance imaging showed a complex cystic lesion. A left open partial nephrectomy was performed and the histopathologic study reported cystic nephroma. The patient had adequate postoperative progression and was released on the 4th day after surgery.

Cystic nephromas are rare lesions that are commonly diagnosed in the postoperative period because their radiologic characteristics are similar to complex cysts suggesting malignancy. Treatment is surgical and nephron-sparing surgery is preferred in young patients with a small lesion.

Cystic nephromas are rare tumors and it is a challenge to differentiate them from malignant renal tumors and thus manage them by sparing functioning renal units whenever possible.