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Hydatid disease involving some rare locations in the body: a pictorial essay.

Yuksel M, Demirpolat G, Sever A, Bakaris S, Bulbuloglu E, Elmas N - Korean J Radiol (2007 Nov-Dec)

Bottom Line: Unusual sites for this disease can cause diagnostic problems.This pictorial essay illustrates various radiological findings of HD in the liver, spleen, kidney, pancreas, peritoneal cavity, omentum, adrenal, ovary, lung, mediastinum and retroperitoneum.Familiarity with the imaging findings of HD may be helpful in making an accurate diagnosis and preventing potential complications.

View Article: PubMed Central - PubMed

Affiliation: KSU Medical School, Department of Radiology, Kahramanmaras, Turkey. myuksel@ksu.edu.tr

ABSTRACT
Hydatid disease (HD) is an endemic illness in many countries, and it poses an important public health problem that's influenced by peoples' socioeconomic status and migration that spreads this disease. Although rare, it may occur in any organ or tissue. The most common site is the liver (59-75%), followed in frequency by lung (27%), kidney (3%), bone (1-4%) and brain (1-2%). Other sites such as the heart, spleen, pancreas and muscles are very rarely affected. Unusual sites for this disease can cause diagnostic problems. This pictorial essay illustrates various radiological findings of HD in the liver, spleen, kidney, pancreas, peritoneal cavity, omentum, adrenal, ovary, lung, mediastinum and retroperitoneum. Familiarity with the imaging findings of HD may be helpful in making an accurate diagnosis and preventing potential complications.

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Type II hydatid cyst is seen on US examination of the liver in a 37-year-old man. Multiple echogenic sand (small white arrows), which is composed of brood capsules and scolices, falls to the dependent portion of the cyst by repositioning the patient. This finding is referred to as the snowstorm sign. Note the early separation of the laminated membrane from the germinal membrane (large white arrow).
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Figure 6: Type II hydatid cyst is seen on US examination of the liver in a 37-year-old man. Multiple echogenic sand (small white arrows), which is composed of brood capsules and scolices, falls to the dependent portion of the cyst by repositioning the patient. This finding is referred to as the snowstorm sign. Note the early separation of the laminated membrane from the germinal membrane (large white arrow).

Mentions: The liver is the most common site of HC. The cysts may cause pain, discomfort, abdominal swelling or a palpable mass or thrill (5, 6). In the early stages of the disease, the appearance of HCs may be uncharacteristic and mimic that of simple cysts. However, the double-line sign can often be seen on sonography in unruptured HCs (Fig. 5) (3, 4). Simple liver cysts do not demonstrate internal structures (2, 3), although multiple echogenic foci due to hydatid sand may be seen within the lesion by repositioning the patient on sonography (Fig. 6) (5). On MRI, a low-signal-intensity rim can be helpful to differentiate a unilocular HC from a simple liver cyst (2). Multiple unilocular cysts are indistinguishable from polycystic disease (2, 5). When echinococcal cysts become enlarged, they can produce pericystic biliary tract dilatation due to the mass effect (Fig. 7) (2, 5, 9). Decreasing intracystic pressure, endocyst degeneration, host response, trauma and medical treatment can cause separation of the endocyst from the pericyst (2, 3). Complete collapse of the endocyst results in a sonographic water-lily sign when the parasite lies in the most dependent part of the cyst or this produces an irregular, solid echo pattern (Fig. 8) (5). The wall of HC, even without calcification, is typically seen as a high-attenuated structure on unenhanced CT (Fig. 1) (3). The calcification may occur in the cyst wall or internally in the cyst, and this is detected on radiography in 20% to 30% of liver HCs (Fig. 3) (2, 3, 5). Following the formation of HC, many potential local complications may develop such as rupture, infection (Fig. 9), perforation to the biliary tree (up to 90% of HCs) (Fig. 10), and involvement of the portal venous system (Fig. 11), diaphragm and thoracic cavity (0.6%-16% of the cases with hepatic HCs) (2, 3).


Hydatid disease involving some rare locations in the body: a pictorial essay.

Yuksel M, Demirpolat G, Sever A, Bakaris S, Bulbuloglu E, Elmas N - Korean J Radiol (2007 Nov-Dec)

Type II hydatid cyst is seen on US examination of the liver in a 37-year-old man. Multiple echogenic sand (small white arrows), which is composed of brood capsules and scolices, falls to the dependent portion of the cyst by repositioning the patient. This finding is referred to as the snowstorm sign. Note the early separation of the laminated membrane from the germinal membrane (large white arrow).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC2627456&req=5

Figure 6: Type II hydatid cyst is seen on US examination of the liver in a 37-year-old man. Multiple echogenic sand (small white arrows), which is composed of brood capsules and scolices, falls to the dependent portion of the cyst by repositioning the patient. This finding is referred to as the snowstorm sign. Note the early separation of the laminated membrane from the germinal membrane (large white arrow).
Mentions: The liver is the most common site of HC. The cysts may cause pain, discomfort, abdominal swelling or a palpable mass or thrill (5, 6). In the early stages of the disease, the appearance of HCs may be uncharacteristic and mimic that of simple cysts. However, the double-line sign can often be seen on sonography in unruptured HCs (Fig. 5) (3, 4). Simple liver cysts do not demonstrate internal structures (2, 3), although multiple echogenic foci due to hydatid sand may be seen within the lesion by repositioning the patient on sonography (Fig. 6) (5). On MRI, a low-signal-intensity rim can be helpful to differentiate a unilocular HC from a simple liver cyst (2). Multiple unilocular cysts are indistinguishable from polycystic disease (2, 5). When echinococcal cysts become enlarged, they can produce pericystic biliary tract dilatation due to the mass effect (Fig. 7) (2, 5, 9). Decreasing intracystic pressure, endocyst degeneration, host response, trauma and medical treatment can cause separation of the endocyst from the pericyst (2, 3). Complete collapse of the endocyst results in a sonographic water-lily sign when the parasite lies in the most dependent part of the cyst or this produces an irregular, solid echo pattern (Fig. 8) (5). The wall of HC, even without calcification, is typically seen as a high-attenuated structure on unenhanced CT (Fig. 1) (3). The calcification may occur in the cyst wall or internally in the cyst, and this is detected on radiography in 20% to 30% of liver HCs (Fig. 3) (2, 3, 5). Following the formation of HC, many potential local complications may develop such as rupture, infection (Fig. 9), perforation to the biliary tree (up to 90% of HCs) (Fig. 10), and involvement of the portal venous system (Fig. 11), diaphragm and thoracic cavity (0.6%-16% of the cases with hepatic HCs) (2, 3).

Bottom Line: Unusual sites for this disease can cause diagnostic problems.This pictorial essay illustrates various radiological findings of HD in the liver, spleen, kidney, pancreas, peritoneal cavity, omentum, adrenal, ovary, lung, mediastinum and retroperitoneum.Familiarity with the imaging findings of HD may be helpful in making an accurate diagnosis and preventing potential complications.

View Article: PubMed Central - PubMed

Affiliation: KSU Medical School, Department of Radiology, Kahramanmaras, Turkey. myuksel@ksu.edu.tr

ABSTRACT
Hydatid disease (HD) is an endemic illness in many countries, and it poses an important public health problem that's influenced by peoples' socioeconomic status and migration that spreads this disease. Although rare, it may occur in any organ or tissue. The most common site is the liver (59-75%), followed in frequency by lung (27%), kidney (3%), bone (1-4%) and brain (1-2%). Other sites such as the heart, spleen, pancreas and muscles are very rarely affected. Unusual sites for this disease can cause diagnostic problems. This pictorial essay illustrates various radiological findings of HD in the liver, spleen, kidney, pancreas, peritoneal cavity, omentum, adrenal, ovary, lung, mediastinum and retroperitoneum. Familiarity with the imaging findings of HD may be helpful in making an accurate diagnosis and preventing potential complications.

Show MeSH
Related in: MedlinePlus