A rare case of pancreatic head hydatid cyst

Learning points for clinicians Hydatid cysts are a common pathology encountered in routine practice. However, these are usually found in liver and less commonly in lungs. The presence of hydatid cyst in pancreas is quite a rare phenomenon and should be suspected in patients from endemic areas and typical imaging features. Hydatid disease is a parasitic disease caused by infection with the larval stage of Echinococcus granulosus. Theoretically, echinococcosis can involve any organ. The liver (63%) is the most common organ involved, followed by the lungs (25%). These two organs account for 90% of cases of echinococcosis.1 Pancreatic hydatidosis remains rare even in countries where the disease is endemic, with an incidence ranging from 0.14% to 2%.2–4 The diagnosis can be difficult, confusing with other cystic lesions of the pancreas. Hydatid cysts may remain silent and asymptomatic or cause severe to life-threatening complications requiring prompt medical treatment. Here, we present a case of a primary hydatid cyst located in the head of the pancreas. A 49 years old female patient was referred from surgery department with complaints of intermittent abdominal pain since 3 months. Ultrasound of the abdomen was performed which showed a well-defined cystic lesion in the pancreatic head with internal echoes and multiple irregular septae within. A contrast-enhanced computed tomography scan of the abdomen showed a well-defined thin-walled cystic lesion of approximate size 7.5 × 9.1 × 8.2 cm seen in the region of pancreatic head. It was seen to be compressing the distal common bile duct which showed mild proximal dilatation of intrahepatic biliary radicals. All hematological and biochemistry investigations done were within normal limits except serum amylase (444) and serum lipase (7101) which were significantly increased. Serum tumor markers such as carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 were normal. Magnetic resonance imaging abdomen was done which was suggestive of a well-defined thin-walled cystic lesion measuring 7.5 × 9.1 × 8.2 cm in the pancreatic head and uncinate region with a hypointense serpentine membrane seen within the lesion. It showed peripheral wall enhancement on post-contrast images. There was no evidence of any solid component within the lesion. No communication with the main pancreatic duct was seen. The patient underwent exploratory laparotomy, which revealed a mass occupying head of pancreas compressing the common bile duct, first and second part of duodenum. By using a needle, thick serous fluid was aspirated which ruled out the possibility of pseudocyst of pancreas. The gross examination of the mass revealed hydatid cyst with its wall. It contained multiple, yellowish, translucent cyst walls. Histopathological examination of the surgical specimen demonstrated a degenerated fibro-collagenous lamellated echinoccocal cyst wall with abundant debris and proto-scolices fragments. Cyst wall showed acute on chronic inflammation. Postoperatively serum ecchinococcus IGG was sent which was 9.28. Hydatid disease is a parasitic infestation by the tapeworm E. granulosus in its larval stage. Hydatidosis is more predominant in sheep-raising communities, where dogs have access to infected offal. Human infection occurs by ingesting food or water contaminated with infected-dog feces containing viable tapeworm eggs. PHCs, despite being rare, have been reported with an incidence of 0.14–2%.2–4 They are commonly seen in the head of the pancreas (50–58%), followed by the body (24–34%) and the pancreatic tail (16–19%).5 Pancreatic infestation by E. granulosus occurs mainly by hematogenous dissemination.6 Radiological imaging and the epidemiological background of patients are the cornerstone for the diagnosis of abdominal hydatid disease. Because of significant morphological changes during hydatid cyst evolution, and the fact that it can affect almost any organ, a definitive diagnosis can be established only after histopathological confirmation. PHC is a rare condition, often confused with cystic pancreatic neoplasms. Although PHC presents a unique challenge in preoperative diagnosis, it should always be considered in the differential diagnosis of cystic pancreatic lesions from endemic areas. Awareness of this phenomenon helps prevent misdiagnosis and inappropriate treatment. Conflict of interest: None declared. (a) Axial CT scan image shows a well-defined thin-walled cystic lesion in the head of pancreas which can also be appreciated on (b and c) MRI images with hypointense serpentine membrane within. (d) Gross examination of the resected mass revealed hydatid cyst with its wall and (e) it contained yellowish translucent debris within. (f) Histopathological examination demonstrated a degenerated fibrocollagenous lamellated echinoccocal cyst wall.