PMC10118874_01
Axial (a-c) and coronal (d) images of contrast-enhanced CT exam show a left upper paravertebral cystic mass (arrows) with daughter cysts (asterisks), peripheral and intrinsic calcifications, adjacent ribs remodeling and erosions, and extension into adjacent left neural foramina (dashed arrows).
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T3 to T5 vertebral bodies. The cystic mass had peripheral and intrinsic calcifications, cysts of different sizes and showed remodeling and erosion of adjacent ribs, with extension into the left T3-T4 and T4-T5 neural foramina (Figure 1).
Axial fused PET/CT images (a, b) show a well-define left paravertebral cystic mass and heterogeneous cystic mass with no significant FDG uptake.
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Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F 18-FDG PET/CT) showed no significant FDG uptake in the lesion (Figure 2).
Coronal (a) and axial (b) T2-weighted images and axial T1-weighted images pre- (c) and post-IV contrast injection (d) show a left paravertebral hydatid cyst. The cystic mass shows numerous and variable in size daughter cysts (asterisks), the rim of low signal intensity on T2-weight images with enhancement in the postcontrast image (arrows), and extension into the adjacent neural foramina (dashed arrows).
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T2 signal intensity compared to the large mother cyst matrix, which had intermediate T1 signal intensity and intermediate to high T2 signal intensity. The lesion also had a smooth, peripheral rim of low T2 signal intensity with postcontrast enhancement (Figure 3). There was no evidence of mural nodules or suspicious solid components, and no imaging signs of hepatic or pulmonary hydatid disease were present.
Axial T2-weighted images before medical treatment (a, b) show the left paravertebral hydatid cyst with numerous daughter cysts (arrows). Axial T2-weighted images postmedical treatment (c, d) show interval rupture of the daughter cysts and visualization of floating membranes (dashed arrows); these findings are compatible with contained rupture.
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Five months after starting medical treatment, a follow-up MRI showed the interval rupture of the daughter cysts and the development of low-signal floating membranes (Figure 4).
Histopathology images using hematoxylin and eosin (H&E) stains. Low power view (H&E 20x, (a)) shows the thick fibrous capsule with a mixed inflammatory infiltrate and granulation tissue. Medium power view (H&E 40x, (b)) shows the inner side of the capsule with a laminated cyst wall lining. A higher power view (H&E 200x, (c)) shows the laminated membrane structure. In the cyst wall, some areas demonstrated acellular laminated membranous structures with cellular debris and calcifications (b, c). The adjacent lung tissue was congested and showed a chronic inflammatory reaction. There were no viable protoscolices in the cyst wall and adjacent lung.
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The histologic findings are consistent with hydatid disease, and there was no evidence of viable protoscolices (Figure 5).