Laparoscopic Injection of Methylene Blue to Discriminate Cyst from Calyceal Diverticulum

Introduction

The kidney is one of the most common sites for the cyst in the body (prevalence about 5%). Kidney cysts are sacs of fluid in the kidneys which are characterized as "simple" cysts with a thin wall (1). They become common as people getting old and are with no symptoms or harm. Because they often don’t cause symptoms are incidentally found by renal imaging including computed tomography (CT) and ultrasonography (2, 3). The prevalence, number, and size of renal cysts are greater in men compared to women and are connected to age, hypertension, and smoke (4). Most renal cysts (sporadic, acquired, or hereditary) arise from parts of nephrons or collecting ducts, while multicystic dysplasia arises before the formation of nephrons (5).
The calyceal diverticulum or pyelocalyceal diverticulum is a urine-containing cystic cavity within the renal parenchyma lining by transitional epithelium and surrounded by muscularis mucosae which are connected to the collecting system (6). The majority of calyceal diverticula can be diagnosed by ultrasound and intravenous urogram (IVU) and retrograde studies are required to confirm calyceal diverticula diagnosis. More often than not, the diverticulum is misdiagnosed as a complex cyst or even as a neoplasm.
The treatment strategy is completely dependent on the exact diagnosis of cysts or calyceal diverticula and it is critical to discriminate cysts from calyceal diverticula. In some patients, there is not possible to place a Double J stent because of the skeletal situation of patients or make the surgery duration shorter. In the current study, we use laparoscopic methylene blue in cysts to ensure there is no contact with the pyelocaliceal system.

Case presentation

A 52-year woman referred to Sina hospital complaining about vague right flank pain and heavy feeling. Her diagnosis was a large flank cyst. She had no family examination, no history of surgery, and no other illness. Abdominal and pelvic computed tomography with and without contrast and simple culture indicated to the 15 cm cyst.
We selected this case and all steps of our study were completely adhere to CARE guidelines. She was the candidate for surgery but there was no certain diagnosis between renal cysts and calyceal diverticulum. In the flank position and through the open access the trocar 15 was embedded. Then peritoneoscopy was performed and 2 trocars 5 were implanted. The colon with strong adhesion was fully medialized. Now the cyst was exposed (Figure 1). The needle was inserted through the skin into the large cyst and sterile methylene blue was injected (Figure 2). The cyst was complete with blue color. The catheter was checked to see whether the blue color enters the urine stream or not (Figure 3). Fortunately, it was completely clear and its roof was unroofed. At the bottoms of the cyst, several small cysts were observed so we inject methylene blue as mentioned above and check for urine color, after approved that the lesions are cyst, the cyst wall was removed. After six weeks and six months, the patient report the satisfying result of surgery with no vague right flank pain or cyst recur in follow-up sonography.

  Figure1. Reveal cyst

                               Figure 2. Injection of methylene blue