Mucinous Cystadenocarcinoma in a Horse Shoe Kidney Masquerading as Giant Hydronephrosis - A Case Report: Diagnostic Challenges, Lessons Learnt and Review of Literature.

Primary epithelial tumour of the renal pelvis is a rare entity. So far, very few cases are reported in literature. Of these, mucin secreting adenocarcinomas are distinctly rare. However, mucinous cystadenocarcinoma, that too arising in a horse shoe kidney is extremely rare to be reported. Mucinous cystadenomas and carcinomas arising from the renal pelvis are regarded to be secondary to a metaplastic change in the urothelium. Here, we present a case of a 51-year-old male, who complained of abdominal pain, palpable abdominal mass, haematuria along with passage of mucoid material in the urine, with a very poorly functioning kidney. A pre-operative diagnosis of horse shoe kidney with pelvi ureteric junction obstruction and a poorly functioning kidney was made. Intraoperative findings and frozen section biopsy were suggestive of mucin secreting cystic mass and a right heminephrectomy was done. The final histopathology was suggestive of mucinous cystadenocarcinoma of the renal pelvis of the right moiety. This case is presented for its rarity, diagnostic challenges faced and the lessons learnt, stressing on the need for having a high index of clinical suspicion in making such diagnosis.