Aneurysmal hemorrhage of the kidney caused by angioleiomyoma.

A small angioleiomyoma consisting of proliferating smooth muscle cells and vessels caused macrohematuria in a 52-year-old female patient. The locally ill-defined tumor in the fatty tissue of the renal pelvis immured small arteries and veins as well as an interlobar artery, and caused damage to the vascular walls accompanied by the development of aneurysm, perforation and fistulation into the renal pelvis, by mechanisms open to various pathogenetic interpretations. Preoperative radiological diagnosis yielded a subcapsular hematoma, and showed more intense contrast medium staining of the upper renal pole. Dysontogenetic tumors are most frequently located in the renal cortex and are capable of locally destructive growth. They are usually well defined and of nodular structure. As, in our case, an exact diagnostic assessment of the process was lacking and both the location and growth pattern of the tumor were atypical, an organ-preserving resection was deemed unsuitable and nephrectomy was performed.