Keywords
cysts - endosonography - hydatid - pancreatitis
Introduction
Hydatid disease is a zoonotic disease caused by the larval stage of Echinococcus species wherein the dogs are the definitive host and sheep and goats are the intermediate
host.[1] Human acquire infection by accidental ingestion of the Echinococcus eggs in dog feces. These eggs give rise to the larvae of the parasite which migrate
from the intestine to the portal circulation. Once in circulation, they can involve
any part of the body with liver being the most common site as it is the first organ
to filter the portal circulation. Other common sites of involvement are lungs, spleen,
and kidney.[1]
[2]
Pancreatic hydatid cyst is uncommon but isolated pancreatic hydatidosis is even rarer.[1]
[2] Cysts in the head of pancreas usually present with jaundice, whereas cysts located
in the body and tail are usually asymptomatic. We present a rare case of isolated
pancreatic hydatid cyst that presented with acute pancreatitis and mimicked a pancreatic
fluid collection.
Case Report
A 17-year-old girl presented with a 1-month history of epigastric pain associated
with high-grade intermittent fever of 3 days duration. The evaluation revealed painful
epigastric lump and leukocytosis with elevated serum amylase levels of 768 U/L. Prima
facie, a possibility of acute pancreatitis with necrotic collection was considered.
Ultrasonography (USG) of the abdomen showed large cystic lesion between the stomach
and spleen. Computed tomography (CT) showed a 12 cm thick-walled cystic lesion containing
air in the distal body and tail of the pancreas ([Fig. 1]). Magnetic resonance imaging (MRI) also revealed a large well-defined cystic lesion
in the pancreas with multiple membranes typical of hydatid cyst ([Fig. 2]).
Fig. 1 Computed tomography: 12 cm thick-walled cystic lesion containing air in distal body
and tail of the pancreas.
Fig. 2 MRI (axial section): large well-defined cystic lesion in pancreas with multiple membranes
(arrow), which is typical of hydatid cyst. Abbreviation: MRI, magnetic resonance imaging.
Endoscopic ultrasound (EUS) confirmed the presence of a cystic lesion in the distal
body and tail of the pancreas. This cystic lesion had multiple daughter cysts suggestive
of hydatid cyst ([Fig. 3]). The pancreatic duct (PD) was seen communicating with the cystic lesion ([Video 1]). Her hydatid serology was positive, and she was started on oral albendazole and
intravenous antibiotics. In view of fever with leukocytosis, endoscopic retrograde
pancreatography and drainage were carried out. The ductal communication was confirmed
([Fig. 4]
[Video 1]), and 7Fr transpapillary nasocystic drain was placed. Her fever subsided and follow-up
USG revealed reduction in the size of the cyst. Subsequently, she underwent distal
pancreatectomy, wedge resection of the adherent gastric wall, and splenectomy ([Fig. 5]).
Video 1
Endoscopic ultrasound showing communication of pancreatic duct with the cyst and endoscopic
retrograde cholangiopancreatography, confirming the presence of duct communication
by leaking contrast. Online content including video sequences viewable at: https://www.thieme-connect.com/products/ejournals/html/10.1055/s-0040-1708069.
Fig. 3 Endoscopic ultrasound: large cystic lesion in distal body and tail of the pancreas
with multiple daughter cysts.
Fig. 4 Endoscopic retrograde pancreatography: contrast leaking from pancreatic duct and
filling the cyst cavity, suggestive of duct communication.
Fig. 5 Surgical specimen: Photograph of cyst cut open showing laminated membrane (black
arrow) and daughter cysts (white arrow).
Discussion
Pancreatic hydatid cysts comprise < 1% of hydatid cysts and should be considered a
differential diagnosis of pancreatic pseudocyst or cystic neoplasm, especially in
endemic regions.[1] However, their rarity is compounded by the overlapping imaging features with other
cystic lesions, which makes preoperative diagnosis difficult. These cysts are usually
solitary (approximately 90%) and commonly located in the head of the pancreas.[2] These cysts may be either primary, involving the pancreas only, or secondary involving
other organs, with liver being the most commonly involved.[2] Blood-borne dissemination is hypothesized to be the most common mode of spread of
larva of hydatid cyst to the pancreas.[2]
[3] Due to the slow growth, the majority of patients are asymptomatic at the time of
detection of the cyst. The symptoms occur because of either fistulization of the cyst
into the PD or external compression of the surrounding structures by the enlarged
cyst. Cysts in the head of the pancreas usually present with jaundice, whereas cysts
located in the body and tail are usually asymptomatic.[2]
[3] Cystopancreatic fistulae are very rare, and only four cases were reported in a review
of 57 patients.[2]
As for any other pancreatic cyst, the most commonly performed imaging investigations
are USG, CT, and MRI.[2]
[3] However, as the pancreas is retroperitoneal structure with visualization impaired
by bowel gases, USG plays a limited role in the evaluation of pancreatic cysts. CT
helps in accurately delineating the cyst along with its size and presence of cysts
in other organs, with MRI and magnetic resonance cholangiopancreatography (MRCP) being
useful in delineating the contents of the cyst along with its relationship with pancreatic
and bile ducts. However, all these imaging modalities have limited sensitivity in
making a specific diagnosis because of considerable overlap of imaging findings.[4] EUS is a newer imaging modality that provides high-resolution images of the pancreas
and is an important investigation procedure for diagnosis and evaluation of pancreatic
cystic lesions.[5] Demonstration of daughter cysts and hydatid sand on EUS can help in the confident
diagnosis of pancreatic hydatid disease, as was in the index case. EUS can also help
in demonstrating the communication of PD with the cyst.[6] No single test can help in the accurate diagnosis of pancreatic hydatidosis, and
its diagnosis is usually made in an appropriate epidemiological setting, with imaging
usually EUS showing daughter cysts and USG, CT or MRI showing an undulating lining
membrane along with peripheral eosinophilia and positive hydatid serology.[4]
[7]
Open surgery is the treatment of choice with the type of surgery dependent on the
site of the cyst.[8] Endoscopic retrograde cholangiopancreatography plays no role in either the diagnosis
or treatment but may be used for palliation and bridge to surgery in patients with
cystopancreatic fistula, leading onto pancreatitis or infection, as was done in the
index case.[2]
[3] Minimally invasive techniques such as USG-guided percutaneous drainage, using hypertonic
(20%) saline or absolute alcohol as scolicidal agents, have been successfully used
for noncommunicating hepatic as well as renal hydatid cysts.[9]
[10] It has also been reported to be successfully used for noncommunicating pancreatic
hydatid cysts.[11] In conclusion, pancreatic hydatid cyst is very rare and should be considered as
a differential diagnosis of pancreatic cystic lesions, especially in endemic areas.
