Two Rare Entities in One Patient: Mucinous Tubular and Spindle Cell Carcinoma of the Kidney and Peritoneal Adenomyomas

Mucinous tubular and spindle cell carcinoma of the kidney is a rare subtype of renal cell carcinoma, that is believed to portend a favorable prognosis. Adenomyomas are benign tumors that typically arise from the myometrium. Extrauterine adenomyomas are extremely rare, with only a few cases reported in the literature. Here, we present an unusual case of a 46-year-old woman, with an incidentally detected bulky interpolar left kidney mass measuring 12 cm and multiple lobulated coalescent peritoneal nodules in the large epiploon suspicious for peritoneal carcinomatosis. A biopsy of the lesions revealed a mucinous tubular and spindle cell carcinoma of the kidney and extrauterine adenomyomas of the peritoneum. A left radical nephrectomy was performed and long-term hormone therapy with gonadotropin-releasing hormone agonists was prescribed. The purpose of this article is to focus on these two rare lesions, review the current literature, illustrate their key imaging findings along with pathologic correlation, as well as to discuss the differential diagnosis and clinical management.