Multiple Fat- Containing Hepatic Hydatid Cysts: A Case Report in The X- Ray Institute at Medical City Health Directorate in Iraq

Background: Hydatidosis is a zoonotic disease caused by Echinococcus granulosus and Echinococcus multilocularis parasite which is still endemic in many countries all over the world especially in the developing countries. The liver is the primary site to be infested by the parasite with a rate of 60 – 75%. The right lobe of the liver gets infected in about 80% of cases. Hydatid disease of the liver is usually asymptomatic and most cases discovered accidentally on routine clinical or radiological examinations for other illness. Symptoms usually appear in complicated cases either due to rupture, secondary bacterial infection, or due to the large size of the cyst which might cause pain in the right upper quadrant of the abdomen, discomfort, and sometimes swelling. In this case report, we reported the presence of fat globules within the hepatic hydatid cysts which is most probably due to rupture of hepatic hydatid cysts into the biliary tree.


Introduction
Hydatidosis is a zoonotic disease caused by Echinococcus granulosus and Echinococcus multilocularis parasite which is still endemic in many countries all over the world especially in developing countries. The world health organization reported the https://djm.uodiyala.edu.iq/index.php/djm Abdul-Wahaab et al Multiple Fat-Containing Hepatic Hydatid Cysts: A Case Report in The X-Ray Institute at Medical City Health Directorate in Iraq incidence rate of hydatid disease exceeding more than 50 infections per 100000 individuals annually [1]. The liver is the primary site to be infested by the parasite with a rate of 60 -75%. The right lobe of the liver gets infected in about 80% of cases. Less commonly the parasite can infest the lungs, brain, spleen, bones, peritoneum, and kidneys. The cyst is composed of 3 lay¬ers: outer, middle and inner layers. The outer layer is referred to as the pericyst which results as a defense mechanism from the tissue against the infestation. The inner or what is called the germinal layer produces the middle laminated membrane (middle layer) and the scolices. The middle and inner layers represent the endocyst [2]. Hydatid disease of the liver is usually asymptomatic and most cases are discovered accidentally on routine clinical or radiological examinations for other illnesses. Symptoms usually appear in complicated cases either due to rupture, secondary bacterial infection, or due to the large size of the cyst which might cause pain in the right upper quadrant of the abdomen, discomfort, and sometimes swelling [3]. Hydatid cysts might have a wide variety of imaging presentations at diagnosis such as simple cysts, cysts with multiple daughter cysts, calcifications whether intralesional or wall calcifications depending on the stage of the disease [4][5][6].
Complications of hepatic hydatid disease include: rupture into peritoneal or thoracic cavities and abscess formation due to secondary bacterial infection [7]. In addition to that hydatid cyst may rupture into the biliary tree [8]. The imaging modality of Hydatid disease represented by ultrasonography, computed tomography (CT) and magnetic resonant imagines (MRI). Ultrasonography is the most commonly used test to diagnose and evaluate hydatidosis of the liver; moreover, it plays an important role in the diagnosis of hydatid disease of spleen, kidneys, heart, pelvis and pleura. The typical ultrasonic finding for hepatic hydatid cyst is a well-circumscribed anechoic lesion that has a posterior acoustic enhancement with no signs of hepatic parenchymal infiltration. The lesion may show fine internal echoes which refer to hydatid sand and represent the debris. The mass effect may be evident when the size of the cyst is large enough to cause pressure on the surrounding structures [9]. Computed tomography and magnetic resonanceimaging have crucial roles in the assessment of extra-hepatic hydatidosis since they give more information about the site, size, and the extent of the lesion. The cyst appears as well-circumscribed hypoattenuating in CT examination and hypointense in T1 or hyperintense in T2 weight MR images. After parentral administration of contrast material, the hydatid cyst shows mild peripheral enhancement [10]. In this case report, we reported the presence of fat globule within the hepatic hydatid cyst which is most probably due to rupture of a hepatic hydatid cyst into the biliary tree.

Case presentation
A 39 year old female patient presented to the international center for medical specialization in Baghdad at the 22 nd of February 2017 complaining of right hypochondrial heaviness and discomfort for the last few months. She was referred to the ultrasonography unit for an abdominal ultrasound. The patient gave a history of https://djm.uodiyala.edu.iq/index.php/djm Abdul-Wahaab et al Multiple Fat-Containing Hepatic Hydatid Cysts: A Case Report in The X-Ray Institute at Medical City Health Directorate in Iraq previous medical visits and checkups from which she discovered the presence of multiple focal lesions in her liver which was thought to be of metastatic character. Abdominal ultrasound was performed for her to find out the lesions. In addition, CT scan was done for better characterization & localization of the lesion & to exclude the possibility of malignancy.

Radiological findings
Abdominal ultrasonography was done by using GE Voluson 735 sonography which revealed the presence of multiple welldefined focal cystic and solid lesions in the right & left lobes of the liver. The cystic lesions showed low-level internal echoes. The lesions were of different sizes and the largest was measuring 80 mm x 69 mm in segment VIII of the right lobe of the liver. CT scan was recommended to exclude metastasis. Thus the patient was examined by using Philips Brilliance 64 CT scanner. The patient was positioned quite supine on the CT scan table. Non-contrast thin sections were carried out through the abdomen to detect any possible hepatic lesions. After that 80 ml of non-ionic contrast material (Ultravist 370 and Omnipaque 350) was injected through a cannula placed in the right antecubital vein at a rate of 5.5 ml/sec. CT scan examination revealed the presence of multiple rounded heterogeneous lesions in the right and left lobes of the liver namely in segment II, IVa, VII, and VIII, and the largest lesion located in segment VIII measuring approximately 77 mm x 71 mm. The lesions appeared to be hypodense with some of them containing fat density globules. Contrast-enhanced CT scan showed no obvious enhancing solid components. There was no evidence of intrahepatic biliary radical dilatation & the liver parenchyma looked normal. The picture was suggestive of multiple hepatic hydatid cysts.
Axial non-contrast CT image shows well-defined cyst in segment VII of the liver with intra-cystic fat globules (red arrow) Axial CECT examination image showed no obvious enhancing solid components https://djm.uodiyala.edu.iq/index.php/djm

Discussions
Hepatic hydatid disease is caused by the larva of tapeworm, E. granulosus [2]. The radiological findings differ depending on the stage of the disease and the growth of the cyst which could be: unilocular simple cyst or complex large cyst with multiple daughter cysts in addition to the cystic wall calcification which could be partial or complete calcification [3]. Hepatic hydatid disease might be discovered incidentally as the patient might be asymptomatic or the patient presents with signs and symptoms due to the occurrence of the complications which could be infection or rupture. The modality of choice for diagnosis of hepatic hydatid disease is the CT scan examination which can detect the hypodense cystic lesion with well-circumscribed wall. The contrastenhancing CT scan reveals the rim enhancement of the wall with air-fluid level can be seen in cases of complications. Rupture of hepatic hydatid cyst occurs in about 20 -50% of cases [13] and the main causes of the rupture are: 1) direct trauma, 2) degeneration of the cyst membranes and 3) rupture after reaching large size [2]. Rupture of hydatid cyst could be of three types:1) contained, 2) direct, and 3) communicating. In the first type the endocyst is ruptured while the pericyst remains intact with the membranes floating inside. Communicating rupture in which the cyst contents pass into the biliary tree. While when there is rupture for both endocyst and pericyst and spillage of the cyst content into the body cavities like pleural, peritoneal and pelvic cavities and into the hollow viscera of the abdomen is called the direct rupture. The presence of fat fluid level within the cyst is regarded as an indirect sign of communication rupture [7]. Previous studies like Mendez Montero et al. (1996) mentioned that the possible causes for the presence of fat globule within a hepatic hydatid cyst might be due to a cyst-biliary communication [7]. Malik et al. (2010) suggested that lipids play an important role in the metabolism of HHCs and that fat-fluid level in an HHC is related to degeneration of hydatid membranes (aging process of the cyst) [

Conclusions
Hepatic hydatid cyst containing fat globules due to cystic rupture into the biliary tree.

Recommendations
It is important to keep in mind intra-biliary rupture of hepatic hydatid cysts.

Source of funding: This research was
funded by ourselves and these is no other funding cover this study or manuscript preparation and publication.