Mediastinal extension of a progressively enlarging pseudocyst treated by EUS-guided transgastric drainage in a child: A rare case report (with video).

A 13-year-old girl was diagnosed with acute idiopathic pancreatitis complicated with pseudocyst 18 months ago. Without significant symptoms related to the pseudocyst, she was followed up in the outpatient clinic. Ten months ago, she was presented with abdominal pain. Abdominal computed tomography (CT) scan was performed, revealing a 7.8 cm × 9.1 cm × 13.1 cm pseudocyst located in the tail of the pancreas. Ultrasound-guided percutaneous drainage of the pancreatic pseudocysts was performed. The cyst regressed significantly and the drainage tube was removed 5 days later. Five months ago, due to dyspnea, the patient underwent a CT of the chest and abdomen, which showed that the pseudocyst was progressively enlarged and occupied a large space of the right thoracic cavity [Figure 1a], acommpanied with left shifting of esophagus and dilataion of pancreatic duct [Figure 1b]. These indicated that the high-pressure pseudocyst penetrated into the right thoracic cavity through the esophageal hiatus and a pancreatic-pleural fistula had been formed. Ultrasound-guided percutaneous drainage of the cyst was again performed uneventfully. Four months ago, the X-ray showed the pseudocyst regressed significantly [Figure 1c] and the tube was removed.Figure 1: (a and b) 2021-5-18 CT of the chest and abdomen (5 months ago): The pseudocyst was progressively enlarged and occupied a large space of the right thoracic cavity, acompanied by left shifting of esophagus and dilatation of pancreatic duct. (c) 2021-6-20 X-ray (4 months ago): The pseudocyst regressed significantly. (d and e) 2021-10-15 CT of the chest and abdomen (before the operation): The pancreatic pseudocyst extended into the posterior mediastinum, accompanied by posterior mediastinal-epigastric cystic mass and compression of the stomach. (f) 2021-10-15 MRCP (before the operation): The pancreatic duct is dilated, but not disrupted. CT: Computed tomography, MRCP: Magnetic resonance cholangiopancreatographyThe patient was referred to our hospital with a recurrence of abdominal pain. She was unable to lie down due to dyspnea. Her height and weight were 158 cm (P50) and 44 kg (P25-P50), respectively. The CT of the chest and abdomen showed a pancreatic pseudocyst extending into the posterior mediastinum, accompanied by left shifting of esophagus [Figure 1d] and compression of the stomach [Figure 1e]. Magnetic resonance cholangiopancreatography (MRCP) was performed, revealing the pancreatic duct was dilated, but not disrupted [Figure 1f]. This indicated that the high-pressure pseudocyst had penetrated into the posterior mediastinum through the esophageal hiatus again. After the discussion among a multidisciplinary team, including endoscopists, interventional radiologists, and surgeons, the EUS-guided transgastric drainage was determined to resolve the severe symptom. EUS (EG-580UT, Fujifilm) showed a large cystic lesion in the body of the pancreas, which extended into the posterior mediastinum. The maximal cross-section size was approximately 16 cm × 12 cm [Figure 2a]. The puncture point was chosen 2 cm below the cardia [Figure 2b]. The 19G puncture needle (M00550001, Boston Scientific) was used to puncture the cyst [Figure 2c] and 6 mL of cyst fluid was aspirated (cyst amylase: 27071 U/L). Then, a 0.035-inch guidewire (M00556581, Boston Scientific) was inserted [Figure 2d]. The tract was dilated using a 10-Fr cystotome (CST-10, Cook Medical), followed by a 10-mm dilation balloon dilator (MBD-0655-18, Micro-Tech (Nanjing)) for 5 min [Figure 2e]. Two double-pigtail plastic stents (7Fr, 7cm) (ZSO-7-7, Cook Medical) and one nasobiliary tube were placed across the dilation tract [Figure 2f]. The procedure was uneventful [Figure 2 and Video 1].Figure 2: (a) EUS showed a large cystic lesion was located in the body of the pancreas, which extended into the posterior mediastinum. The maximal cross-section size was approximately 16 cm × 12 cm. (b) Endoscopy showed the lower esophagus and stomach fundus were deformed under compression, and the puncture point was 2 cm below the cardia. (c) EUS image showed the 19G puncture needle was used to puncture the cyst. (d) Endoscopy showed a 0.035-inch guidewire was inserted into the cyst. (e) Endoscopic image showed the tract was dilated using a 10-Fr cystotome followed by a 10-mm balloon dilator. (f) Endoscopy showed two double-pigtail plastic stents and one nasobiliary tube were inserted across the dilation tractFollow-up of CT after 2 days of the operation revealed a dramatic decrease in the cystic size [Figure 3a]. The nasobiliary tube was removed 4 days later. Due to the global pandemic of COVID-19, the patient was delayed to attend our hospital 7 months after the operation. She was free of symptoms and her height and weight were separately increased by 7 cm and 20 kg. A repeat CT confirmed the complete resolution of the posterior mediastinal-epigastric cystic mass [Figure 3b]. Then, the two stents were removed [Figure 3c]. Follow-up of CT after 2 months reported a reduction of the mediastinal pseudocyst, the residual cavity contains viscous proteinaceous effusion, and the patient is asymptomatic [Figure 3d]. The patient continues to be followed up regularly.Figure 3: (a) 2021-10-22 Follow-up CT (2 days after the operation): A dramatic decrease of the cystic size. (b) 2022-5-17 A repeat CT (7 months after the operation): Complete resolution of the posterior mediastinal-epigastric cystic mass. (c) 2022-5-17 Endoscopy (7 months after the operation): Removal of two stents. (d) 2022-7-25 Follow-up CT (2 months after stent removal): Reduction of the mediastinal pseudocyst, with the residual cavity containing viscous proteinaceous effusion. CT: Computed tomographyMediastinal extension of pancreatic pseudocysts is a rare complication of acute pancreatitis, especially in children. Up to date, only 14 pediatric cases with mediastinal extension of pancreatic pseudocyst have been reported. Ten of these cases underwent cystogastrostomy, Roux-en-Y cystojejunostomy, thoracoscopic drainage, or Puestow’s procedure, whereas four received EUS-guided transesophageal drainage. These procedures were uneventful and the patients recovered well.[1,2] The choice of surgical approach depends on the anatomic location of the cyst. Cystogastrostomy is preferred for retrogastric cyst adherent to the stomach, whereas pseudocysts located at the base of transverse mesocolon are best drained by cystojejunostomy. Endoscopic cyst drainage procedures through transesophageal, transgastric, or transpapillary routes have been described in the literature.[3,4] However, these methods are mainly reported in the adult population, and endoscopic transmural drainage is rarely reported as a lack of expertise in the pediatric age group. It remains unclear whether the mediastinal extension of pseudocysts is more common in children than adults due to the less strong barrier of the diaphragm. In addition, while most pseudocyst extension results in the occupation in the left thoracic cavity, the pseudocyst of the present case extended to the right side of the thoracic cavity. Although various management options are available for the management of mediastinal pancreatic pseudocyst, the individualized treatment plan is made according to the underlying cause, anomaly of the pancreatic duct, and symptoms experienced by the patient. This case further demonstrated the advantages of EUS-guided transmural drainage in the treatment of pancreatic pseudocyst. If technically possible, EUS-guided transmural drainage, as a less invasive, effective, and radiation-free method, can be considered the appropriate alternative for the treatment of pancreatic pseudocysts in children. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the parents have given their consent for the child’s images and other clinical information to be reported in the journal. The parents understand that the child’s names and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed. Financial support and sponsorship This study was supported by grants from the Special Project of Chinese Digestive Endoscopy Innovation Development (Z-2019-45-2001), Science and Technology Action Plan of Xi’an Science and Technology Bureau (20YXYJ0002 [4]), Project of Xi’an Children’s Hospital (2020C09), and Project of Xi’an Children’s Hospital (2020D03). Conflicts of interest There are no conflicts of interest.