The term calyceal diverticulum refers to a urine-containing cystic cavity within the renal parenchyma. The calyceal diverticulum is lined by transitional epithelium and communicating with the collecting system via a narrow isthmus or infundibulum. Demonstrating a connection between this fluid-filled space and pelvicalyceal system in contrast studies, such as com¬puted tomography or urography is the key diagnostic finding. Diagnostic difficulties are related to their resemblance to other cystic lesions, including simple cysts, hydronephrotic dilatation of pelvicalyceal system in a duplex kidney and cystic renal tumors. There are two recognised types. Type 1 is the more common form, which communicates with a renal calyx and is usually found in the upper pole. Type 2 is less common, larger, communicates directly with the renal pelvis and found in the interpolar region of the kidney. Type 2 calyceal diverticula may also be termed pyelocalyceal diverticula, reflecting their communication with the renal pelvis. They are generally benign and asymptomatic, although complications include infection and stone formation. Occurrence of the complications may be an indication for treatment.

In this study, a different treatment approach for calyceal diverticulum that was radiologically misdiagnosed as a communicating-type renal cyst was presented. This misdiagnosed led to previous unsuccessful laparoscopic management and further ultrasound-guided percutaneous aspiration and alcohol injection.

A 40-year old female presented to our hospital owing to a left flank pain. Ultrasound (US) and computed tomography (CT) scans revealed a huge renal cyst, measuring 121x97x72 mm arising from the mid-pole on lateral side of the left kidney (probably type 2 calyceal diverticula). Further evaluation with the CT scan showed the presence of contrast agent extravasation into renal cyst on late phase imaging. The transperitoneal laparoscopic management was preferred due to symptomatic communicating-type renal cyst. The first step was the insertion of a ureteral catheter in the lithotomy position to kept accessible for retrograde instillation of methilen blue. A conventional laparoscopy set and 30 degrees telescope is used. A four trocar laparoscopic decortication of renal cyst and closure of the communicating channel by suturing (4/0 Vicryl) were performed for treatment on 45degrees lateral decubitus position. A retrograde pyelog¬raphy was performed to confirm no extravasation. JJ stent was inserted on dorsal lithotomy position following laparoscopic approach. Histopathological examination revealed that the cystic lesion was lined with urothelium originating from the pelvicalyceal system. Because of this unexpected pathological result and recurrence of the cyst, alcohol ablation was planned on post operative period. The cystography demonstrating no extravasation and then alcohol ablation was performed. Despite the alcohol injection both the pain and the cyst was sustained, so an open surgical approach was performed including these steps as follows; excision of the diverticulum and then urothelium, the cauterization of the sub-epithelium and primer defect repair of the renal parencyhma on right flank position. The patient was discharged on post-operative 5 day. Histopathological examination revealed no evidence of neither urothelium nor another epithelial cells, probably due to alcohol ablation.

Calyceal diverticulum should be kept in mind in the differential diagnosis of communicating-type renal cyst.