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Biliary cystadenoma in an endemic zone of hydatid cyst: A rare surgical surprise

The advancement of radiological investigations has led to the early and incidental detection of hepatic cystic lesions. These are most commonly the simple cysts but can be malignant as well. Despite the recent advances, these lesions still pose a diagnostic as well as therapeutic challenge. The biliary cystadenomas and carcinomas form around 5% of all the malignant cystic lesions of liver. These lesions are hardly diagnosed preoperatively and are usually a histopathological surprise. They warrant a surgical excision. Herewith, the authors are describing a case of cystic hepatic neoplasm initially misdiagnosed as hydatid cyst of liver and discovered to be a vascular cystic lesion intraoperatively. This patient underwent resection of the lesion and was discovered to harbour biliary cystadenoma on histopathological specimen.


INTRODUCTION
Hepatic cystic lesions (HCL) are increasingly been encountered in modern day surgical practice. 1 These are usually asymptomatic and are incidentally found on radiological investigation for unrelated problem. The lesions are usually benign however can be malignant as well. 2,3 These cystic lesions comprise of constellation from a benign simple cyst to a malignant cystadenocarcinoma. The benign lesions can be observed but the malignant ones need to be investigated and treated properly.
Biliary cystadenoma (BC) are rare HCL. They comprise of 5% of the cystic lesions. 4 These lesions are more commonly reported in middle aged group females. 5 They are usually asymptomatic however can lead to symptoms when the adjacent visceral structures are compromised. 6 Echinococcal cysts or hydatid cysts of the liver can closely mimic these lesions in the endemic areas. 7,8 The diagnosis of hydatid cyst is essentially radiological according to the World health organization (WHO) classification. The false negative serology in hydatid cyst also poses a diagnostic dilemma. 9 Herewith the authors are describing a male patient with large HCL involving the right lobe of the liver.
He was diagnosed with hydatid cyst on initial radiological tests and subsequently found to have vascular cystic neoplasm intraoperatively. He underwent an excision of the lesion and discovered to harbour a biliary cystadenoma without a focus of malignancy. The rarity of these lesions in males along with the associated diagnostic and surgical surprise makes this case a unique report.

CASE
A 25 year male without any associated comorbidities presented to our outpatient department with complaints of pain in right hypochondrium for last 5 years which was intermittent and dull aching in nature. There were no aggravating or relieving factors. There were no associated symptoms. Clinically there was a large mass involving the right hypochondrium and lumbar regions. This was mobile with respiration and had irregular surface and margin.
The dullness over the mass was continuous with the liver  With the preoperative diagnosis of hydatid cyst this patient was optimized and prepared for surgery. He underwent the DJ stenting of the right ureter followed by laparotomy with excision of the cystic mass. Intraoperatively, a large mass involving the right lobe of liver was identified. This mass was abutting the antropyloric region of the stomach and right kidney but could be separated from them. Fluid aspiration from the mass yielded mucinous fluid hence a decision of formal excision was made.
The mass was excised without any capsular breach. The cut section of mass showed multiloculated cystic lesion with mucinous fluid within it (Fig. 2). The patient had an The cyst wall contained fibrocollagenous tissue with macrophages and lymphocytes at places. There was the presence of proliferating lymphatic and vascular channels.
There was absence of ovarian stroma, parasite or a neoplastic process. Estrogen and Progesterone immunostains were negative. The features were consistent with a biliary cystadenoma without any focus of malignancy (Fig. 3).

DISCUSSION
HCL are increasingly been encountered in the modern day surgical practice. 1 They include the spectrum of benign simple cysts to a malignant cystic lesion. The parasitic infections also add to the surgical challenges especially in the endemic areas. Biliary cystadenomas form 5% of the total HCL. 4 The incidence rate of these lesions is 1 in 20000-1 in 40000. 10 The etiology of these lesions is largely unknown however a congenital malformation of biliary epithelium is suggested. 5 These are indolent lesions and the rate of growth is very slow. They can turn malignant if neglected. The middle aged females form 85% of the patients. 11 Liver (85%) is the most commonly involved viscera however, extrahepatic bile ducts as well as gallbladder can also be affected in rare cases. 12 The presence of this cyst in a male patient and mimicking a hydatid cyst in an area endemic for echinococcosis makes the index patient an unique report.
Biliary cystadenomas are usually asymptomatic. These are indolent and rarely symptomatic. These symptoms arise secondary to the the adjacent visceral compromise.
There may be obstructive jaundice due to common bile duct compression, 13 bilateral pedal edema or deep vein thrombosis in case of inferior vena caval obstruction. 6 The present patient had hydronephrosis secondary to ureteral compression necessitating a preoperative ureteral stenting. www.ahbps.org The wide variety of HCLs in the liver pose a diagnostic challenge. The hydatid cyst of the liver as well as the liver abscess are the most common space occupying lesions (SOL) that resemble cystadenomas. 7,8 The aspiration of the liver abscess is therapeutic but it is contraindicated both in hydatid cyst as well as cystadenoma 14 due to risk of anaphylaxis as well as seeding respectively. These cysts may be a differential diagnosis for intrahepatic cholangiocarcinoma or the cystic variant of cholangiocarcinoma as well. 6 Vonmeyenburg complex and other variants of hepatic plate dysgenesis syndromes may closely mimic these lesions. 15 The BC is usually an incidental finding. The liver function test and biochemical profile is usually normal. The serum tumor markers are recommended to rule out any hepatic malignancy. Serum hydatid serology and amoebic serology must be performed in endemic areas. 6 The false negative rates of the serologic tests are in range of 20% 9 which means the hydatid cyst being the more common SOL in endemic area should be considered in priority.
The present case is the classical example where the pres- Writing -Review and editing: LK.