Evaluation of imaging features of pelvic echinococcosis based on multimodal images

Abstract

Background Hydatid disease (HD) is a zoonotic parasitic disease caused by the larvae of Echinococcus, It is mainly prevalent in pastoral areas. Bone echinococcosis is rare, accounting for 0.5 to 4.0% of all echinococcosis. It is likely to miss the diagnosis and misdiagnose due to non-specific early symptoms and the clinical manifestations and imaging features. The clinical data of 15 patients with pelvic cystic echinococcosis were analyzed retrospectively, and the X-ray, CT, and MRI imaging features of the disease were discussed, which are reported below. Methods All 15 patients underwent CT scan evaluation. A total of 8 patients underwent coronal, sagittal, and three-dimensional reconstruction with 3-mm-slice thickness, and 4 patients underwent X-ray plain film examination. Five cases underwent MRI scan. Eight cases underwent MRI or CT enhanced scan. Results X-ray plain film is characterized by continuous cystic bone destruction, irregular low-density shadow when invading soft tissue, and sometimes calcification which can be seen on the wall or inside the cyst. The involved sacroiliac joint or hip joint may narrow or disappear. The involvement of pelvic cystic echinococcosis is relatively wide, and 80% of patients with pelvic cysts in this group had multiple lesions in the same period. Cystic expansive bone destruction was the most common. Pelvic CT revealed a lobulated hypodense lesion of varying size with internal septae, causing cortical thinning and destruction. Most of them had no periosteal reaction. The iliopsoas muscle is most easily invaded. Single cystic echinococcosis of pelvis showed intermediate or low signal intensity on T1-weighted images and hyperintensity on T2-weighted images in the involved bone and surrounding soft tissue on MRI, and the cyst wall showed linear low signal in T1WI, T2WI, and STIR sequences. The polycystic type is characterized by multiple cysts of varying signal intensity (daughter cysts) within a larger cyst is the typical MRI finding, forming “small vesicles” high signal daughter cysts. Osteosclerosis or calcification showed low signal in T1WI and T2WI. Conclusions The results of this study suggest that the lesions of pelvic cystic echinococcosis are mostly cystic expansive and osteolytic bone destruction, which is easy to invade the surrounding soft tissue, often accompanied with calcification; among them, multiple cystic lesions are characteristic.

Primitive pelvic bone hydatidosis: What an amazing extension

“…8,9 When located in the bone marrow cavity, hydatid lesions grow slowly; they can spread along the trabecular bone and cause bony destruction. 5 They can penetrate through the bone cortex and overrun the surrounding soft tissue. Unlike other viscera, there is no adventitia formation in skeletal hydatidosis; thus, daughter cysts…”

“…13 Epidemiological arguments might help the diagnosis as history of pastoral contact seems to be an important risk factor. 3,5 In addition, a relatively higher prevalence of hydatid disease was noted in the rural populations and that is mainly attributable to the slaughtering of animals in these areas. 5 However, those elements are not always present, as it is in our case, and their absence should not misguide the diagnosis.…”

“…3 The intralesional calcifications should be looked for as they are highly suggestive of hydatid bone disease and help in the differential diagnosis. 5 However, they are rare and they are more frequent in the extraosseous parts. 15 In pelvic bones, CT scans typically reveal single or multiple hypodense lesions with internal septa.…”

“…1,4 Although it is an old disease, the diagnostic of hydatid bone is still challenging given the delayed clinical manifestations and the nonspecific radiological features. 5 We herein report a case of a primary bone hydatid disease of hip, pelvis, and the surrounding soft tissues.…”

Hydatid cysts of the pelvis following pulmonary hydatid disease: A rare case report

“…It results in the replacement of the trabecular bone by various slow-growing vesicles that proliferate along the medullary canal, without creating encapsulated cysts similar to other organs; therefore, diagnosis can be delayed (9). Osseous hydatidosis is usually diagnosed in advanced stages when the cyst has enlarged and caused complications, such as infection or abscess fistula, neural deficits, osteolytic bone destruction, invasion to soft tissues, and pathological fractures (6,10).…”