[Retroperitoneal myxoid leiomyoma: report of a case].

We report a case of retroperitoneal myxoid leiomyoma in a 36-year-old woman complaining of urinary retention. An ultrasonogram revealed a mass in the pelvic space, while CT and MRI demonstrated a retroperitoneal tumor. Open resection of the tumor was performed. The resected tumor weighed 600 g and measured 16 x 11 x 9 cm. Histological examination disclosed a tumor mainly composed of smooth muscle with myxomatous change and only rare mitoses. The pathologic diagnosis was retroperitoneal myxoid leiomyoma. Twenty-seven cases of this type of lesion previously reported in the Japanese literature were reviewed.