Mucinous adenocarcinoma of the renal pelvis with pseudomyxoma peritonei

Mucinous adenocarcinoma of the renal pelvis is an extremely rare tumor with very few case reports in literature. Pseudomyxoma peritonei is an uncommon condition characterized by the presence of mucinous gelatinous material in the peritoneal cavity. It occurs secondary to primary mucinous neoplasms of particularly the appendix and the ovary. We present a case of a 35-year-old female who had a history of dull aching pain in the right flank since one and a half years. Upon ultrasonography (USG) and computerized tomography (CT) scan, there was a large cystic mass measuring 15x15x12 cm, extending into the right lumbar region. Grossly, the entire kidney was converted into a cystic mass measuring 15x15x12 cm containing gelatinous mucinous material weighing 1 kg. Histologically, the tumor was composed of simple and complex glandular acini together with a superficial resemblance to colonic mucosa with abundant extracellular mucin. Thus, a diagnosis of mucinous adenocarcinoma of the renal pelvis leading to pseudomyxoma peritonei was made.