Renal leiomyoma

Renal leiomyomas are benign tumors of the kidney originating from smooth muscle cells of the renal capsule, pelvis, calyces, or blood vessels.

There is a 4-5.5% prevalence based on autopsy findings ¹.

Clinical presentation

Renal leiomyomas are usually incidental findings. In symptomatic cases, these lesions can cause abdominal/flank pain and/or palpable mass ¹.

Pathology

At macroscopic examination, leiomyomas are typically well-demarcated, solid, firm nodules with rare calcifications and cystic changes, without necrosis.

Microscopically, spindle cells with few nuclear polymorphisms and no mitotic activity are arranged in intersecting fascicles ².

Diagnosis

Diagnosis in based on histological analysis.

Radiographic features

Ultrasound

Ultrasound may display a solid or cystic mass and allow for identification of a plane between the tumor and kidney, but has very poor specificity ¹.

DSA-angiography

• can be either hypo- or hyper-vascular
• features indicative of malignancy (e.g. vessel encasement, renal vein invasion, arteriovenous shunting) are absent ¹

CT

Computed tomography scanning provides improved anatomic definition and reveals well-circumscribed margins, a capsular/subcapsular or peripelvic origin, minimal parenchymal distortion, and no evidence of extra-renal invasion ¹. Some suggest attenuation value, location and margins of the lesion can help to address the diagnosis of renal leiomyoma ².