Introduction

 

Hydatid disease is a serious public health problem in endemic areas. Most common site of involvement is liver. However, extrahepatic sites such as lung, spleen, bone, kidneys and retroperitoneum have been described. Primary pancreatic lesions are very rare for hydatid disease with an incidence of less than 1%.[1,2,3] The diagnosis is challenging and rarely made before surgery as the presenting symptoms and radiological findings may be similar to other commonly encountered cystic lesion of pancreas. We share our experience in a case of pancreatic hydatidosis, masquerading as a cystic neoplasm of the pancreas.

 

Case Report

 

A thirty years old lady presented with a history of lump abdomen for the last two months. This was associated with dull aching pain in the epigastric region. There was history of progressively increasing jaundice which was associated with itching and clay coloured stools. History of weight loss and anorexia was present. On examination, she was found to be deeply icteric. Her abdominal examination revealed a 10 x 8 cm globular lump in the epigastrium moving freely with respiration which was not continuous with liver dullness. The clinical diagnosis of surgical jaundice with a palpable gall bladder was made.

 

On investigation, her liver function tests revealed a total bilirubin of 13.8 mg/dl (normal- 0.8-1.0 mg/dl) with direct fraction of 11.0 mg/dl. Liver enzymes were mildly elevated (alanine transaminase-56 IU/L, aspartate transaminase-72 IU/L). The alkaline phosphatase was elevated to 2331 IU/L (normal 80-240 IU). Ultrasonography of the abdomen revealed mild hepatomegaly, distended gall bladder and dilated common bile duct. Magnetic resonance cholangio-pancreatography (MRCP)  demonstrated a cystic swelling in close relation with the lower end of common bile duct with dilated common hepatic duct and intra hepatic biliary radical dilatation (Figure 1). The gall bladder was distended and MRCP suggested a diagnosis of type III choledochal cyst. On endoscopic ultrasound, it was diagnosed as a lesion arising from head of pancreas most probably a serous cystadenoma.

 

On laparotomy, there was an 8 x 6 cm cystic lesion arising from the head of pancreas which was compressing the distal common bile duct. Intra operatively a diagnosis of cystic neoplasm of head of pancreas (Figure 2) was made and a Whipple’s pancreaticoduodenectomy was done. Patient had an uneventful post operative recovery. On cut section of the  specimen, the cyst had a thick wall (Figure 3) with clear fluid and no daughter cysts. The cyst was communicating with the main pancreatic duct and the common bile duct was separately opening into the duodenum. On histopathological examination, the cyst had laminated membranes with a pericyst and endocyst, features compatible with that of a hydatid cyst of the pancreas. In view of the hydatid disease patient was started on oral albendazole at a dose of 400 mg twice daily for 6 weeks. After 6 months the patient is asymptomatic and there is no evidence of hydatid disease anywhere else in the body.

 

Discussion

 

First described by Talmund as “bladder full of water’, hydatid disease is most commonly caused by Echinococcus granulosus. Liver is the most common organ to get involved (55-75%) followed by lung (18-35%).[1] Other sites described include the peritoneal cavity, kidney, spleen, bone, retroperitoneum. Most of these occur concurrently with liver hydatid. Pancreatic hydatidosis is rare (0.3-2%)[1,2,3] and primary pancreatic hydatid disease even rarer with only 40 cases being reported in medline4 over the last 30 years.

 

Pancreatic infestation can occur via haematological spread, peripancreatic lymphatic invasion, retroperitoneal spread and local spread via pancreatic/bile ducts.[5]

 

A number of cystic lesions can involve the pancreas including benign lesions (such as congenital pancreatic cysts, pseudocysts) and malignant cysts (such as serous/mucinous cystadenocarcinoma and endocrine tumors of pancreas). Although the cystic neoplasm of head of pancreas are not very common but still the incidence of cystic neoplasm is much higher than hydatid cyst of head of pancreas.[6] It is very difficult to differentiate hydatid cyst of pancreas from other cystic lesions and a high degree of clinical suspicion is required.

 

Preoperatively a fine needle aspiration of the cyst and biochemical and microbiological examination for hydatid antibodies, carbohydrate antigen-19.9, amylase and presence of live scolices can help in differentiating a hydatid cyst from a pseudocyst of pancreas and malignant cystic lesions of head of pancreas. Pancreatic hydatid cysts are most commonly located in the head of pancreas (57%) followed by body (24%) and tail (19%). The clinical presentation is highly variable. They can be asymptomatic or present as obstructive jaundice (as in our case), or as acute/chronic pancreatitis.[7,8,9] Lesions in tail of pancreas can rarely present with portal hypertension.

 

The diagnosis is based on an enzyme-linked immunoadsorbent assay (ELISA) test for echinococcal antigens, which is positive in over 85% of infected patients.[10] Ultrasonography will typically demonstrate daughter cysts. Contrast enhanced computed tomography (CECT)/magnetic resonance imaging (MRI) may show the presence of daughter cyst though this is not always the rule. The diagnosis is usually made on laparotomy.[11] In our case CECT and MRI failed to provide a diagnosis because of the location of cyst in the head of pancreas. There was no suspicion of hydatid disease in our patient preoperatively as well as intra-operatively. The diagnosis of hydatid cyst came as a histological surprise and even on cut section there was only clear fluid and no daughter cysts.

 

The definitive treatment of pancreatic hydatid is surgical. Various methods have been described depending on the location of the cyst such as total/subtotal cystectomy, distal pancreatectomy (for tail of pancreas cyst), cystoenteric anastomosis, deroofing and omentoplasty and external drainage. However, when the diagnosis has not been made even a pancreaticoduodenectomy has been performed mistaking it to be a cystic neoplasm of pancreas.[12] In our case also pre-operative and intra-operative diagnosis was of a cystic neoplasm of head of pancreas. Our patient underwent a pancreatodeudonectomy.

 

Adjuvant medical therapy is reserved for patients where complete surgical excision is not possible or patients unfit for surgery.

 

In conclusion, primary hydatid disease of pancreas is extremely rare. However, a high degree of clinical suspicion should be kept whenever dealing with cystic lesions of pancreas especially in endemic areas as it is very difficult to arrive at a diagnosis pre-operatively.

 

References

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5.     Kayabali I, Gokcora IH, Ormeci N. Surgical treatment of hydatid cysts of the pancreas. Int Surg. 1991;76:185–8.

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7.     Ozmen M, Moran M. Recurrent acute pancreatitis due to a hydatid cyst of the pancreatic head: a case report and review of the literature. J Pancreas (Online). 2005;6:354–8.

8.     Regan JK, Brown RD, Marrero JA, Malik P, Rosenberg F, Venu RP. Chronic pancreatitis resulting from primary hydatid disease of the pancreas: a case report and review of the literature. Gastrointest Endosc. 1999;49:791–3.

9.     Sayek I, Onat D. Diagnosis and treatment of uncomplicated hydatid cyst of the liver. World J Surg. 2001;25:21–7.

10.   Saidi F. Surgery of the Hydatid Disease. Philadelphia, PA: Lippincott Williams & Wilkins; 1976.

11.   Khiari A, Mazli R, Ouali M, Kharrat M, Kechaou MS, Beyrouti MI. Hydatid cyst of the pancreas: Apropos of 7 cases. Ann Gastroenterol Hepatol (Paris). 1994;30:87–91.

12.   Lemmer ER, Krige JE, Price SK, Girdwood AH.Hydatid cyst in the head of the pancreas with obstructive jaundice. J Clin Gastroenterol. 1995;20:136–8.