A 7-year-old male child was presented to the Pediatric Department in Shatbi University Hospital with recurrent chest infections since 1 year. Repeated chest X-ray showed left pleural effusion. The child was managed conservatively and discharged from the pediatric department. During the course of follow-up for the respiratory condition an abdominal ultrasound was ordered to investigate a new onset minor abdominal discomfort. An abdominal cyst was found which, otherwise, was not clinically palpable during abdominal examination. Subsequent computed tomography (CT) scanning of the abdomen and pelvis with intravenous contrast revealed a retroperitoneal thick-walled fluid filled mass, measuring approximately 11.5 x 13 cm in close relation to the main pancreatic duct with inflammation of the adjacent pancreatic tissue. Provisional reports indicated a pseudo-pancreatic cyst with further extension into the posterior mediastinum through one of the diaphragmatic hiatus ( Fig. 1 ). Serum amylase and lipase were markedly elevated (amylase: 45,630 U/I and lipase: 180,000 U/I). 
The decision after surgical consultation was to perform laparotomy. The child was prepared for the operation. Through an upper midline incision, the abdomen was explored. This revealed a large, smooth, and fluctuant mass behind the stomach extending up to the posterior mediastinum through the esophageal hiatus, mostly arising from the pancreas. Aspiration of the coffee ground contents was done followed by a drainage procedure by anastomosing the posterior wall of the stomach to the anterior wall of the cyst wall (cystogastrostomy) using running 4/0 vicryl sutures. A Penrose drain was inserted in the left upper quadrant followed by a layered closure. The postoperative course was uneventful. Nasogastric suction and intravenous fluids were continued for 5 days, after which oral feedings were gradually given. The drain was removed after 5 days and the child was discharged from the hospital on the 9th postoperative day. Follow-up abdominal ultrasound was done after 2 weeks and revealed dramatic improvement regarding the size of the cyst. Serum amylase gradually fell to the normal limits. A repeat ultrasound confirmed complete resolution of the cyst after 6 months. The patient is doing well after 1 year of regular follow-up visits.