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

Abstract

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.

Keywords: Adenomyoma; Carcinoma; Kidney; Peritoneum; Renal Cell.

Fig. 1

Pelvic MRI. Axial (a) and coronal (b) T2-WI show a hyperintense bulky left kidney mass. White arrowheads: renal cell carcinoma. Black star: renal parenchyma.

Fig. 2

CT scan of the abdomen and pelvis illustrates a marked increase in left renal dimensions, conditioned by the presence of a massive solid interpolar ovoid lesion. On unenhanced CT (a), the baseline attenuation value of the lesion was 28 Hounsfield units (HU). With contrast injection, the mean attenuation was 36 HU at the cortico-medullary phase (b), 47 HU at the nephrographic phase (c), and 63 HU at the excretory phase (d). White arrowheads: renal cell carcinoma. Black star: renal parenchyma.

Fig. 3

CT scan of the abdomen and pelvis demonstrates multiple lobulated iso to hypodense coalescent peritoneal nodules with moderate enhancement. White arrows: peritoneal nodules.

Fig. 4

Microscopic pathology of the mucinous tubular and spindle cell carcinoma of the kidney composed of tubular and spindle cell components separated by mucinous stroma (hematoxylin-eosin stain, 5x).

Fig. 5

Gross photograph of the excised omental lesion (a) shows a circumscribed tan-white nodule. Microscopic pathology shows smooth muscle tissue with benign endometrial glands surrounded by a rim of endometrial stromal, compatible with adenomyoma (b: hematoxylin-eosin stain, 0.25x; c: hematoxylin-eosin stain, 2x).