Teaching Case

The patient presented with abdominal pain and loss of weight. Laboratory tests confirmed that she had anemia, mild eosinophilia and an increased level of alcalic phosphatase. An abdominal CT scan demonstrated a multiloculated cystic mass originating from the tail of the pancreas. Mural calcification could be noticed.

The patient presented with abdominal pain and loss of weight. Two years earlier, she had undergone excision of a hydatid cyst in the liver. Laboratory tests confirmed that she had anemia, mild eosinophilia and an increased level of alcalic phosphatase. She was referred to our department for a sonographic examination of the abdomen. A cystic lesion with internal septa could be vaguely revealed near the splenic hilum, but its origin could not be recognized. Therefore, this was followed by a CT scan of the abdomen. The scan demonstrated a multiloculated cystic mass 8 cm in diameter and originating from the tail of the pancreas. Mural calcification could be observed. Taking into account her previous medical history, the diagnosis of a pancreatic hydatid cyst with daughter cysts was suggested. Laboratory tests specific for hydatid disease confirmed the diagnosis. Partial pancreatectomy was performed, and the patient was discharged a few days later.

Hydatid disease is most commonly caused by Echinococcus granulomatosus. It is endemic in certain regions such as Asia, Australia, South America and Southern Europe. Humans are affected either by direct contact with a dog or by ingestion of contaminated food and fluids. The larvae, which are freed from the eggs in the upper gastrointestinal tract penetrate the mucosa of the jejunum and enter the blood circulation. Once they enter the blood stream, they infest the liver and the lungs, which represent a “barrier” to further spread the infection in the body and are the usual sites prone to hydatid disease (90% of the cases). Involvement of the pancreas, either primary or secondary, is very rare (less than 0,1%). The head of the pancreas is affected in half of these cases. The primary disease occurs when the larvae escape from the liver and the lung barrier, whereas the secondary disease occurs after the rupture of a subcapsular hepatic cyst. Depending on its locatio,n a pancreatic hydatid cyst can manifest clinically with jaundice, cholangitis and pancreatitis or can be clinically asymptomatic and represent an incidental finding. The diagnosis of a hydatid cyst is suggested when a multiloculated lesion, representing daughter cysts, with calcified walls is found but it is not confirmatory. A previous history of hydatid disease or the presence of demographic risk factors can facilitate the diagnosis, but in any case confirmation of the radiological diagnosis of hydatid disease is based upon the positive results of specific serological tests, such as the indirect hemagglutination test, ELISA with the presence of the arc 5 of Capron, etc. We should keep in mind the fact that these tests are negative within months or years of treatment or death of the hydatid cyst. Based on imaging findings alone, differential diagnosis from other cystic lesions such as simple cysts, pseudocysts, neoplasms (microcystic adenoma and mucinous cystic neoplasm) and cystic metastases is needed. A knowledge of the patient’s medical history is important for assessing such lesions. In cases of a unilocular cyst, the diagnosis of a pseudocyst is highly probable, when there is a history of pancreatitis, trauma or alcoholism. Simple cysts are another entity which should be considered. These are rare, congenital lesions and represent a usual finding in patients with dominant autosomal polycystic disease and in von Hippel-Lindau syndrome. In cases of multilocular cystic lesions, demonstration of markedly enhancing soft tissue components after intravenous administration of a contrast medium supports the diagnosis of a microcystic adenoma. Mucinous cystic neoplasms represent other multiloculated lesions that should be differentiated and these are hypovascular. Mural and internal calcifications are commonly found in both, but microcystic adenomas usually affect an older age group (60 to 70 years old) when compared to mucinous cystic neoplasms (affecting those around 50 years old). Surgery remains the treatment of choice, and the extent of the excision depends on the location and the size of the lesion. The combination of surgery and chemotherapy is highly effective in reducing the risk of recurrence due to peritoneal spillage.