Year : 2006 | Volume
: 16 | Issue : 3 | Page : 333--334
Isolated skeletal and splenic hydatid disease
S Uysal, D Gokharman, I Tuncbilek, M Kacar, H Yigit, Ugur Kosar
Department of Radiology, Ankara Training and Research Hospital, Ankara, Turkey
Fakulteler mah. Cemal Gürsel cad, Bahar apt 68/6 Cebeci 06590 Ankara
|How to cite this article:|
Uysal S, Gokharman D, Tuncbilek I, Kacar M, Yigit H, Kosar U. Isolated skeletal and splenic hydatid disease.Indian J Radiol Imaging 2006;16:333-334
|How to cite this URL:|
Uysal S, Gokharman D, Tuncbilek I, Kacar M, Yigit H, Kosar U. Isolated skeletal and splenic hydatid disease. Indian J Radiol Imaging [serial online] 2006 [cited 2020 Feb 28 ];16:333-334
Available from: http://www.ijri.org/text.asp?2006/16/3/333/29009
Hydatid disease (HD) is caused by Echinococcus granulosus. Due to the natural evolution of the parasite, the journey starting in the liver can end anywhere in the body. The presence of hepatic or pulmonary cysts may help to diagnose other secondary organ involvements, whereas primary/isolated manifestations are harder to diagnose. Both the spleen and the bone are the rare primary sites of cyst formation and this often presents as a clinical and radiologic diagnostic problem. Skeletal and splenic involvement accounts for less than 1-4% and 0.9-8% of all HD respectively . Familiarity with imaging findings, especially in endemic areas, may be helpful in making prompt, accurate diagnosis, but it must be kept in mind that atypical features with unusual locations must not exclude the diagnosis. We present a case of hyatid disease with atypical location; i.e. the tibia and spleen, with no other organ involvement.
Materials and Methods
A 35-year-old male patient was admitted to the hospital with a painless, progressively increasing lump in the left lower cruris. On physical examination, there was a fixed and rigid mass on the anterolateral part of the left tibia. Plain radiogram of the left tibia showed diaphyseal osteolytic destruction and expansion with cortical thinning and an associated soft tissue swelling; there was no pathological fracture [Figure 1]. Computed tomography (CT) confirmed the multiloculated osteolytic lesion causing cortical thinning and expansion of the diaphysis of the tibia [Figure 2]. CT additionally showed increased density of the neighbouring bone marrow with an associated soft tissue mass. During systemic evaluation by abdominopelvic ultrasound (US) and CT, a splenic cystic 5 cm-mass with internal and capsular calcification was observed[Figure 3]. Serologic tests were negative. These findings were found to be compatible with HD of the spleen and tibia. During operation, skeletal HD was confirmed followed by medical treatment for splenic HD.
HD is most commonly found in the liver and the lung because the eggs of the parasite are filtered out by the liver in 70% of cases and in the lung in 20% of cases, thus only 10% entering general circulation ,.
Secondary involvement can be defined as extension from the liver or pulmonary circulation with the presence of cysts in those organs, whereas the isolated disease elsewhere is defined as primary involvement . It is known that primary skeletal or splenic involvement is much rarer than the secondary involvement ,,. The skin tests are non-specific and serologic tests are of limited value. They are often negative without hepatic and lung involvement .
Skeletal involvement occurs frequently in adults. It has been most commonly reported in the vertebra, pelvis, femur, and tibia. A definitive diagnosis is made in half of the patients preoperatively . Skeletal HD can often be asymptomatic for a long period because of slow growth. It is usually noticed after certain complications, such as secondary infection, mass-like effect or a sudden fracture with no healing ,,. Skeletal HD occurs mostly in richly vascularized areas such as the epiphyses of the long bones, although atypical oseeous locations such as the diaphysis as in our case may be seen. Soft tissue extension is frequent ,,,. The osteolytic lesion can be uniloculated or more frequently multiloculated. As pericyst formation does not occur in bone, the wall of the cyst is thinner than expected. This, combined with the rigid nature of bone, causes the cyst to be in a non-spherical shape . With the replacement of osseous tissue by the parasite, expansion and cortical destruction occur by time. Radiologically, the lesion usually lacks sclerosis and periosteal reaction. Pathological fractures are common and in this case, the evidence of repairment is usually very little ,,,,,. The disease can spread from bone to surrounding soft tissues ,,. Intraosseous HD rarely shows calcification whereas extraosseous HD may calcify and large lesions with soft tissue calcification are highly suggestive of skeletal HD ,. The differential diagnosis of a skeletal HD includes simple/aneurysmal cyst, abscess, a lipoma, and a malignant tumour. The findings helping differential diagnosis are lack of osteoporosis, soft tissue calcification and a pathological fracture with no evidence of healing ,. Although CT appearances of skeletal HD are similar to those demonstrated on plain films, CT can recognise the internal multicystic nature of the lesion with associated bone marrow and soft tissue changes better and easier. The complications can also be demonstrated by CT accurately ,,.
The involvement of other organs must be evaluated by CT and US if the diagnosis of skeletal HD is considered. In our case, as we assumed the patient to have skeletal HD, during abdominopelvic evaluation we found a calcified cystic mass in the spleen. Primary splenic HD is very uncommon ,,,,. Secondary splenic HD can generally develop by means of systemic dissemination or intraperitoneal spread from a ruptured liver cyst ,,. The clinical manifestations are usually nonspesific with abdominal pain or an incidentally discovered splenomegaly ,,. Splenic HD is usually solitary, exhibiting fluid content with water attenuation values on CT. Mural calcification may be seen and multiple daughter cysts within a large cyst may also be present ,,,. The imaging characteristics are similar to those of hepatic HD ,. These findings help in differentiating the lesion from an epidermoid cyst, a pseudocyst, solitary abscess or hematoma and cystic neoplasm of the spleen. The clinical history, imaging findings, and serologic tests may be helpful in discriminating other splenic lesions.A fine needle biopsy should not be performed because of causing illness extension or anaphylactic reaction.
Although US and CT allow recognition of HD with specific radiologic signs, in the case of the lack of these signs, the diagnosis can be made by a combination of clinical history, imaging findings, and serologic test results. Familiarity with imaging findings, especially in endemic areas, may be helpful in making prompt, accurate diagnosis.
Primary splenic or skeletal HD with no associated pulmonary-hepatic involvement is rare. Our case is a good example and we could not decide about whether the splenic or the skeletal HD was the primary source. This report aims to remind that any cystic lesion in the body may be due to HD and the presence of an osseous expansile cystic mass-even though atypically diaphseal located- with an associated splenic calcified cyst may be diagnostic of HD. Imaging modalities are helpful and generally sufficient to diagnose HD preoperatively as well as investigating the recurrences postoperatively.
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