Answer for BIR CoW 23 Feb 2025
HEPATIC HYDATID CYST
Findings
Evidence of large well defined lobulated exophytic multiloculated T1 hypointense,T2 Hyperintense cystic lesion noted arising from left lobe of liver measuring 12.2 (anteroposterior)x 17.1(transverse)x 15.5 (craniocaudal) cm causing compression of body of stomach and pancreas posteriorly with mild dilatation of distal MPD. Numerous T2 Hyperintense daughter cysts of varying sizes noted within the lesion with surrounding areas of diffusion restriction with low ADC values in the intercystic region. The lesion causes mass effect laterally over the hepatic hilum and gall bladder. No evidence of IHBRD.
DIAGNOSIS
HEPATIC HYDATID CYST - TYPE II / { TYPE CE3b (WHO) }
Stage : Transition stage
Management : Surgical + Albendazole
Discussion
Hydatidosis : The liver is the most affected organ in the body for hydatid disease because it is the first filter of portal venous blood and stops about 75% of ingested embryonated E.granulosus eggs. Hydatid cysts of the liver are often asymptomatic and often represent an incidental finding on medical imaging; however, manifestations may occur due to cyst expansion, leading to hepatomegaly or inflammatory reactions of the host. The principal complications are hydatid cyst infection, biliary duct fistula, and rupture into the peritoneum or chest. Ultrasounds are considered the best and the most convenient imaging modality for liver hydatid cysts. They are a screening modality with a monitoring efficacy of treatment of up to 90% diagnostic accuracy, depending on the operator’s experience. An ultrasound can clearly demonstrate the hydatid sand, membranes, daughter cysts, and vesicles inside the hydatid cyst. It can differentiate hydatid cyst Type I of the liver from simple liver cysts with 96% and 98% sensitivity and specificity, respectively. CTs can differentiate hydatid cyst Type I with 80% and 62% sensitivity and specificity, respectively. A CT has a sensitivity rate of 94% to approach liver hydatid cysts and is important in detecting calcification in the cyst wall or septa, demonstrating cystic structures, assessing complications, and in cases of obesity, excessive bowel gases, abdominal wall deformities, and previous surgery. Magnetic resonance (MR) may be performed to confirm the hypothesis of hepatic hydatidosis and visualize the lesion in different planes. It is the best diagnostic tool for differentiating the cystic component from others and demonstrating biliary tree involvement. Hydatid cysts show variable signal intensities on T1- and T2-weighted images, depending on their internal components. The necrotic and fluid components appear hypointense on T1-weighted images and markedly hyperintense on T2-weighted images. Daughter cysts, when present, appear as cystic structures attached to the germinal layer and are hypointense relative to the intracystic fluid on T1-weighted images. A characteristic feature of hydatid disease is the pericyst, which usually appears as a low-signal-intensity rim on T2-weighted images. An intermediate-signal-intensity inner ring may also be seen, representing membrane detachment. After intravenous gadolinium injection, the pericyst may show slight enhancement. MR is particularly useful for detecting floating membranes and irregularities of the rim, which indicate early membrane detachment. However, MR is less sensitive than CT for detecting cyst wall calcification. The "snake sign," another typical MR feature, represents collapsed parasitic membranes due to cyst damage or degeneration. These membranes exhibit low signal intensity on all sequences. Additionally, an intracystic air-fluid level may be visible on MR, suggesting superinfection. MR cholangiopancreatography (MRCP) is valuable for assessing biliary tree involvement, such as cyst-biliary communication or biliary dilatation secondary to cyst compression. Routine MRI does not reliably differentiate completely liquid hydatid cysts (type I) from simple cysts. However, diffusion-weighted MRI (DW-MRI) has been shown to be helpful in this differentiation. Initially used for brain imaging, DW-MRI has been adapted for abdominal imaging with faster sequences. Using DW-MRI with a high b-factor (1000 s/mm²), hydatid cysts appear hyperintense, whereas simple cysts do not show significant hyperintensity. Additionally, apparent diffusion coefficient (ADC) values can be used to distinguish hydatid cysts from simple cysts. The hydatid cyst’s content, which includes viscous hydatid sand with scolices, proteins, and polysaccharides, results in lower ADC values. In contrast, simple cysts, having lower viscosity, exhibit higher ADC values. In patients with hepatic hydatidosis, contrast-enhanced MR angiography may help detect hepatic venous outflow obstruction, thrombosis, or invasion. Pulmonary embolism remains a possible complication in these cases. The management of hydatid cysts includes medical therapy, percutaneous therapy, and surgical intervention. Medical therapy alone using mebendazole or albendazole has less than a 30% success rate. Surgery remains the most effective therapy, with about 30% postoperative complications, such as biliocutaneous fistula and infection, and a demand for prolonged postoperative hospitalization. The size of hydatid cysts is considered a significant predictor of morbidity and mortality, and the residual cavity is a challenging postsurgical problem in large hydatid cysts and is associated with a high risk of infection. Minimally invasive methods have fewer complications and shorter hospitalizations.
REFERENCES
Hydatid Disease: A Radiological Pictorial Review of a Great Neoplasms Mimicker; Diagnostics 2023, 13(6), 1127; https://doi.org/10.3390/diagnostics13061127 - Multidisciplinary imaging of liver hydatidosis; World J Gastroenterol. 2012 Apr 7;18(13):1438–1447. doi: 10.3748/wjg.v18.i13.1438
Findings
Evidence of large well defined lobulated exophytic multiloculated T1 hypointense,T2 Hyperintense cystic lesion noted arising from left lobe of liver measuring 12.2 (anteroposterior)x 17.1(transverse)x 15.5 (craniocaudal) cm causing compression of body of stomach and pancreas posteriorly with mild dilatation of distal MPD. Numerous T2 Hyperintense daughter cysts of varying sizes noted within the lesion with surrounding areas of diffusion restriction with low ADC values in the intercystic region. The lesion causes mass effect laterally over the hepatic hilum and gall bladder. No evidence of IHBRD.
DIAGNOSIS
HEPATIC HYDATID CYST - TYPE II / { TYPE CE3b (WHO) }
Stage : Transition stage
Management : Surgical + Albendazole
Discussion
Hydatidosis : The liver is the most affected organ in the body for hydatid disease because it is the first filter of portal venous blood and stops about 75% of ingested embryonated E.granulosus eggs. Hydatid cysts of the liver are often asymptomatic and often represent an incidental finding on medical imaging; however, manifestations may occur due to cyst expansion, leading to hepatomegaly or inflammatory reactions of the host. The principal complications are hydatid cyst infection, biliary duct fistula, and rupture into the peritoneum or chest. Ultrasounds are considered the best and the most convenient imaging modality for liver hydatid cysts. They are a screening modality with a monitoring efficacy of treatment of up to 90% diagnostic accuracy, depending on the operator’s experience. An ultrasound can clearly demonstrate the hydatid sand, membranes, daughter cysts, and vesicles inside the hydatid cyst. It can differentiate hydatid cyst Type I of the liver from simple liver cysts with 96% and 98% sensitivity and specificity, respectively. CTs can differentiate hydatid cyst Type I with 80% and 62% sensitivity and specificity, respectively. A CT has a sensitivity rate of 94% to approach liver hydatid cysts and is important in detecting calcification in the cyst wall or septa, demonstrating cystic structures, assessing complications, and in cases of obesity, excessive bowel gases, abdominal wall deformities, and previous surgery. Magnetic resonance (MR) may be performed to confirm the hypothesis of hepatic hydatidosis and visualize the lesion in different planes. It is the best diagnostic tool for differentiating the cystic component from others and demonstrating biliary tree involvement. Hydatid cysts show variable signal intensities on T1- and T2-weighted images, depending on their internal components. The necrotic and fluid components appear hypointense on T1-weighted images and markedly hyperintense on T2-weighted images. Daughter cysts, when present, appear as cystic structures attached to the germinal layer and are hypointense relative to the intracystic fluid on T1-weighted images. A characteristic feature of hydatid disease is the pericyst, which usually appears as a low-signal-intensity rim on T2-weighted images. An intermediate-signal-intensity inner ring may also be seen, representing membrane detachment. After intravenous gadolinium injection, the pericyst may show slight enhancement. MR is particularly useful for detecting floating membranes and irregularities of the rim, which indicate early membrane detachment. However, MR is less sensitive than CT for detecting cyst wall calcification. The "snake sign," another typical MR feature, represents collapsed parasitic membranes due to cyst damage or degeneration. These membranes exhibit low signal intensity on all sequences. Additionally, an intracystic air-fluid level may be visible on MR, suggesting superinfection. MR cholangiopancreatography (MRCP) is valuable for assessing biliary tree involvement, such as cyst-biliary communication or biliary dilatation secondary to cyst compression. Routine MRI does not reliably differentiate completely liquid hydatid cysts (type I) from simple cysts. However, diffusion-weighted MRI (DW-MRI) has been shown to be helpful in this differentiation. Initially used for brain imaging, DW-MRI has been adapted for abdominal imaging with faster sequences. Using DW-MRI with a high b-factor (1000 s/mm²), hydatid cysts appear hyperintense, whereas simple cysts do not show significant hyperintensity. Additionally, apparent diffusion coefficient (ADC) values can be used to distinguish hydatid cysts from simple cysts. The hydatid cyst’s content, which includes viscous hydatid sand with scolices, proteins, and polysaccharides, results in lower ADC values. In contrast, simple cysts, having lower viscosity, exhibit higher ADC values. In patients with hepatic hydatidosis, contrast-enhanced MR angiography may help detect hepatic venous outflow obstruction, thrombosis, or invasion. Pulmonary embolism remains a possible complication in these cases. The management of hydatid cysts includes medical therapy, percutaneous therapy, and surgical intervention. Medical therapy alone using mebendazole or albendazole has less than a 30% success rate. Surgery remains the most effective therapy, with about 30% postoperative complications, such as biliocutaneous fistula and infection, and a demand for prolonged postoperative hospitalization. The size of hydatid cysts is considered a significant predictor of morbidity and mortality, and the residual cavity is a challenging postsurgical problem in large hydatid cysts and is associated with a high risk of infection. Minimally invasive methods have fewer complications and shorter hospitalizations.
REFERENCES
Hydatid Disease: A Radiological Pictorial Review of a Great Neoplasms Mimicker; Diagnostics 2023, 13(6), 1127; https://doi.org/10.3390/diagnostics13061127 - Multidisciplinary imaging of liver hydatidosis; World J Gastroenterol. 2012 Apr 7;18(13):1438–1447. doi: 10.3748/wjg.v18.i13.1438
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!