Mediastinal Pancreatic Pseudocyst in Children: A Case Report and Review of Literature.

Mediastinal pancreatic pseudocyst (MPP) is an infrequent complication of acute pancreatitis in children. A contrast-enhanced computed tomogram (CECT) of the chest and abdomen can aid in diagnosing pleural effusion and MPP. We describe a child with MPP in whom a transcutaneous computed tomogram-guided external drainage was curative. The case is being presented, and the relevant literature is highlighted in view of rarity of this entity. Copyright:

INTRODUCTION

Respiratory complications of acute pancreatitis are common, and they can range from minimal pulmonary atelectasis to respiratory failure. Pleural effusion, mediastinal pancreatic pseudocyst (MPP), and pancreaticopleural fistula are rare complications seen in children after acute pancreatitis.[1] Mediastinal extension of peripancreatic fluid usually occurs through the esophageal or aortic diaphragmatic hiatus.[2] MPP can be managed conservatively or by surgical modes of management. Herein, we report a case of a 6-year-old boy with MPP who was managed by a transcutaneous computed tomogram (CT)-guided external drainage. We aim to highlight the importance of guided external drainage of the pseudocyst in the management of children with MPP. We have also carried out a PubMed search on MPP in children and included all the recently published (since the year 2000) reports to highlight the recent trends in the management of this rare condition.

CASE REPORT

A 6-year-old boy presented to the outpatient department with episodic dull-aching pain in the left upper abdomen for the past 2 years. The pain was intense, dull-aching, radiating to the left side of the chest, and required parenteral analgesics for relief. On physical examination, the child was tachypneic and had decreased air entry in the left infrascapular region. His blood investigations were within normal limits apart from an elevated serum amylase level (200 IU/L). Chest skiagram showed blunting of the left costophrenic angle and left lower zone collapse. Ultrasound of the abdomen revealed an atrophied pancreas and a peripancreatic pseudocyst. CECT and magnetic resonance imaging (MRI) of the abdomen were done to characterize the pseudocyst and the pancreatic parenchyma and ducts. They revealed two well-defined cystic lesions involving the pancreatic parenchyma (the larger cyst around the body and the tail and the smaller cyst around the head and uncinate process). One of the cysts had a supradiaphragmatic extension through the esophageal hiatus and led to the compression of the left atrium and atelectasis of the left lower lobe of the lung [Figure 1a and 2a, b]. The CECT also confirmed the presence of an atrophic pancreas [Figure 1b] with a mildly dilated main pancreatic duct (4.6 mm). While the intrathoracic cystic collection was subjected to CT-guided pigtail drainage [Figure 2c] through a posterior approach, the small intra-abdominal cyst was not drained. The child made an uneventful recovery and was discharged after 24 h of observation. At follow-up after a week, the drainage from the catheter had become minimal, and MRI was done to reassess the residual collection, if any [Figure 2d]. Another MRI after 6 months showed that both the collections had resolved, and the child had become asymptomatic.

Figure 1

Mediastinal pancreatic pseudocyst. (a) Contrast-enhanced axial computed tomogram shows a large fluid collection in the middle mediastinum (white arrow) located posterior to the esophagus (black arrow) and aorta. Mild left pleural effusion (small white arrow) with collapsed left lower lobe is also noted. (b) Atrophied pancreas, dilated main pancreatic duct (white arrow), and a small collection in the head of the pancreas (black arrow) consistent with changes of pancreatitis

Figure 2

Magnetic resonance imaging abdomen and computed tomogram-guided drainage in mediastinal pancreatic pseudocyst. (a) T2-weighted image shows hyperintense fluid collection (white arrow) posterior to the esophagus (black arrow). (b) T1-weighted image shows the hyperintense signal suggesting hemorrhagic fluid (white arrow). (c) Computed tomogram-guided drainage with pigtail catheter (arrow). (d) Follow-up magnetic resonance imaging after 1 week shows a significant reduction in the size of collection. Pigtail catheter seen in situ (arrow)

DISCUSSION

Left-sided pleural effusion following pancreatitis is quite common and is associated with a raised pleural fluid and serum amylase levels. Pseudocyst formation after acute pancreatitis is seen in 7%–15% of cases.[2] Mediastinal extension of these pseudocysts is rare, and only a few cases have been reported in children till date. On searching the literature for cases of MPP published in the English language in PubMed, we found that the first case of MPP was reported in a 10-year-old girl by Galligan and Williams in 1966.[3] Since 2000, only nine cases have been published [Table 1]. Only one of them had a prior history of trauma before the development of MPP.

Table 1

Summary of reports (since the year 2000) in the literature on mediastinal pancreatic pseudocyst in pediatric age

Case number	Author/year	Age at diagnosis (in years)	Clinical features	Initial treatment	Final treatment
1	Kotb et al./2019[1]	7	Recurrent chest infections	Conservative (details not mentioned)	Cystogastrostomy
2	Halder et al./2018[4]	8	Chest painRespiratory distress	Thoracocentesis	Roux-en-Y cystojejunostomy
3	Nabi et al./2018[5]	11	Chest painAbdominal pain	Conservative	Endoscopic transesophageal drainage and stenting
4	Basu et al./2017[2]	7	Cardiac tamponade (massive pericardial effusion)Abdominal pain	Pericardiocentesis, octreotide	Roux-en-Y cystojejunostomy
5	Nuwayhid et al./2011[6]	4	Blunt traumaAbdominal pain, vomitingDysphagiaAnorexia	CT-guided pigtail drainage	-
6	Visrutaratna and Ukarapol/2010[7]	14	PalpitationsDysphagiaPain abdomen	Details not mentioned (clinical image only)	Details not mentioned (clinical image only)
7	Snajdauf et al./2007[8]	3	Pancreatic pseudocyst with abdomen and mediastinal recurrence(primary features not mentioned)	Laparotomy and drainageCystogastrostomy	Roux-en-Y pancreaticojejunostomy
8	Balasubramanian et al./2004[9]	16	Details not mentioned	Pericardiocentesis and pleurocentesis	Roux-en-Y pancreaticojejunostomy
9	Bonnard et al./2001[10]	11	Details not mentioned	Thoracoscopic drainage	-
10	This case	6	Abdominal pain	CT-guided pigtail drainage	-

CT: Computed tomogram

Posterior pancreatic ductal disruption into the retroperitoneum leading to peripancreatic fluid collection initiates the etiopathogenesis of MPP. Extension of this fluid into the mediastinum can occur through all diaphragmatic hiatuses. In the majority of these cases, an extension is seen through the esophageal or aortic hiatus into the posterior mediastinum;[12] however, in rare instances, the fluid can access the foramen of Morgagni and reach anterior mediastinal space also. Within the mediastinum, it can get walled off to form a pseudocyst or rarely percolate into the pleural cavity causing pleural effusion.

Clinical features of children with mediastinal pseudocyst are nonspecific and usually reflect the mass effect on the adjoining structures. This may include abdominal pain, vomiting, anorexia, dysphagia, chest pain, tachypnea, and respiratory distress. Due to the decompression of the fluid around the pancreas into the chest, a palpable cyst during the abdominal examination may not be apparent.[1] An elevated serum amylase level is often seen at the time of presentation but is not specific. Ultrasonography of the abdomen can reveal pancreatic abnormalities, but CECT scan is a better radiologic modality to characterize MPP. It helps us in defining the extent of pseudocyst in the mediastinum, the presence of calcification, and delineating the diaphragmatic communication (esophageal hiatus in the index case).[1] Not routinely used, but magnetic resonance cholangiopancreatography or endoscopic retrograde cholangiopancreatography can help us in defining the fistulous tract and ductal anatomy preoperatively.[6]

Although rare, spontaneous resolution of MPP is reported in the literature. Therefore, a watchful period of 4–6 weeks can be opted for in asymptomatic cases.[6] Various management options are described for MPPs. Medical measures predominantly include octreotide and total parenteral nutrition in the acute phase.[4] Endoscopic drainage of MPP (through transesophageal or transgastric route) is commonly reported in adults. However, reports on these procedures in the pediatric population are limited.[6] Only one case in our review was treated by endoscopic transesophageal drainage and stenting.[5] Open surgical options include cystogastrostomy, cystojejunostomy, and lateral pancreaticojejunostomy/modified Puestow procedure. Both surgical and medical modalities of management have their own merits and demerits. An individualized approach should be adopted after considering the advantages and disadvantages.

Another treatment modality is percutaneous extrapleural CT-guided drainage. It can be employed for solitary cysts. Apart from the index case, the literature review revealed only one pediatric case where percutaneous extrapleural drainage was adopted.[6] We had opted for CT-guided drainage (and not the open drainage procedures) because the mediastinal component was larger and dominant. Follow-up imaging revealed resolution of both the cysts and supported this decision.

CONCLUSION

MPPs are rare complications of acute pancreatitis in pediatric age group. Although various management options are available for their management, an individualized approach should be adopted. Percutaneous extrapleural CT-guided drainage can be considered in a selected subset of patients.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.10

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.