Renal capsule leiomyoma: case report

We present a case of leiomyoma of the renal capsule in a 49 year-old woman that was detected incidentally during an abdominal study for gastroesophageal reflux. We discuss the clinical, radiological and pathological diagnosis of renal leiomyoma as well as its treatment alternatives.

Ultrasonography, CT and MRI were performed. A conventional pathological analysis including immunohistochemistry was performed after radical nephrectomy.

Ultrasonography detected a solid hypoechoic mass poorly vascularized in the upper pole of the right kidney. CT and MRI detected a well-delimited mass showing soft tissue density without extension to the neighbor structures and without lymphadenopathies. Radical nephrectomy was performed. Microscopically, the mass was made of a low-grade fusocellular proliferation with cells staining with antibodies against smooth muscle markers. The mass was in continuity with the renal capsule and compressed slightly the renal parenchyma without damaging it.

Renal leiomyomas are unfrequent benign tumors that should be suspected in young and middle aged women showing asymptomatic, well delimited and hypoechoic renal tumors with soft tissue density in CT scans. When vascular structures are not involved by the tumor, a conservative surgical intervention could be the first therapeutic option. Microscopically, renal leiomyomas are low-grade fusocellular tumors showing a smooth muscle immunohistochemical profile.