[CT Findings of Mucinous Adenocarcinoma Arising from the Renal Calyx in Horseshoe Kidney: A Case Report].

Mucinous adenocarcinoma of the kidney is an extremely rare cystic malignant tumor with a poor prognosis that occurs in the pelvicalyceal system. Pre-opeartive diagnosis is very difficult because the tumor's clinical and imaging features are nonspecific. Here we report a case of primary mucinous adenocarcinoma arising from the horseshoe kidney in a 69-year-old male, focusing on CT findings. The tumor was a complex cystic mass with irregular wall thickening, multifocal calcifications, and septa and progressed to pseudomyxoma peritonei postoperatively.