A Rare Case of Spinal Hydatid Cyst Presented with Compressive Myelopathy

Sir, Hydatid disease is an unusual form of zoonosis affecting humans. The causative agent of the disease is a tapeworm Echinococcus granulosus.[1] Carnivores such as dogs or cats are the definitive hosts, and herbivores such as sheep or cows are the intermediate hosts for the disease. Human infestation is incidental and occurs as an intermediate host. The disease presents in the form of cysts forming almost every viscus; hepatic involvement is the most common involvement in humans. Accidental ingestion of the tapeworm eggs is followed by hatching in the human intestine and infiltration into the bloodstream. Various body viscera are involved by hematogenous spread, where the pathogen develops into a cystic mass.[2,3] Isolated vertebral involvement is an infrequent occurrence. The patient presents with symptoms ranging from backache to paralysis. It is challenging to diagnose the disease preoperatively even in the endemic regions because of its rarity and overlapping imaging features. Magnetic resonance imaging (MRI) provides a detailed assessment of the disease and its complications such as cord compression. We highlight the role and importance of MRI in diagnosing this rarer presentation of this rare disease.[4] A 48-year-old female patient presented with gradually progressive paraparesis and was bedridden. The patient was non-symptomatic 6 months ago, and then she developed a tingling sensation and numbness in both feet with occasional slippage of the footwear. The patient gradually developed knee stiffness while standing up from a sitting position over the last 4 months. The patient also had pain in the mid part of the back. For the last 2 months, the patient developed constipation and urgency of micturition. The patient started feeling band-like sensations around the umbilical region and increased stiffness in both lower limbs over the last month. The patient also started complaining about a loss of touch sensation below the umbilical region. One day before the hospital visit, she experienced a sudden jerk-like sensation in the back while getting up from the bed, and after that, she had a loss of power in her lower limbs and loss of bowel/bladder control. The patient also complained about an on/off fever for 6 months. No previous history of any previous surgery or trauma was given. On clinical examination, only 2/5 motor response was present with a sensory level at the D12 level. An area of focal gibbous deformity could be felt in the lower dorsal spine; however, no associated skin changes were present. Arterial examination of both lower limbs was within the normal range. The patient was advised for an MRI of the dorsal spine. On MRI, a well-defined dumb-bell-shaped multilocular cystic lesion was observed in the D12 vertebral body. The lesions measured about 60 × 80 mm with paraspinal and epidural extensions [Figure 1a and b]. Abnormally high T2 signals were observed in the cord, representing cord edema [Figures 1a and 2b]. The cysts were of varying sizes and the contents of the cysts followed fluid signal intensities on all MRI sequences [Figure 1b and c]). The dorsal spinal cord was nearly completely compressed and displaced posteriorly [Figure 2a]. No restricted diffusion was observed in the lesion. On the imaging findings, the possibility of hydatid disease was suggested.Figure 1: (a) T2-Weighted mid-sagittal MRI image denotes complete collapse of D12 vertebra with anterior and epidural soft tissue extension. The spinal cord is severely compressed and shows abnormal increased T2 signals suggestive of edema (horizontal white arrow). (b and c) T2- and T1-weighted parasagittal MRI images show multiple daughter cysts in the lesion. The cyst content is hypointense on T1 and hyperintense on T2 weighted images (horizontal white arrow)The patient underwent a surgical procedure to relieve the cord compression, and it revealed multiple grape-like vesicles of varying sizes in the lesion [Figure 2c], which favored the diagnosis of hydatid cyst and was subsequently confirmed on histopathology [Figure 2d].Figure 2: (a) T2 weighted axial MRI image reveals the multilocular and multi-septate appearance of the lesion with paraspinal, pre spinal, and epidural extension. The cord is compressed posteriorly (horizontal white arrow). (b) A coronal T2-weighted MRI image depicts the complete collapse of the D12 vertebra and bilateral paraspinal daughter cysts (horizontal white arrow). (c) Intraoperative image showing grape-like vesicles in the lesion (horizontal white arrow). (d) Histopathology image under 10× resolution shows laminated cyst wall comprising endocyst, ectocyst, and pericyst of the hydatid cyst (horizontal white arrow)Hydatid disease is an uncommon disease; however, it is endemic in certain parts such as India. Although it can affect any organ, spinal involvement is reported in less than 1% of cases. Many bacterial and other parasitic affections of the spinal column are prevalent in these regions, most commonly tuberculosis.[4,5] The mode of spread to the spine is hematogenous, where the larva matures into a space-occupying multilocular cystic mass. The lesion typically does not involve an adjacent disc or cross the joint. The lesion destroys the vertebra’s typical scaffolding and expands into paraspinal spaces. The epidural component may also develop, which is the cause of the symptoms in most patients. At last, partial to near-complete vertebral collapse ensues, resulting in a curvature deformity.[4,5] MRI provides a detailed and accurate assessment of pathology, and it also helps in excluding the other diagnosis. Other commoner pathologies of the spine include metastases, tuberculosis, primary bony neoplasm, plasmacytoma, and Langerhans cell histiocytosis (LCH).[5,6] Metastases are usually multiple and may have a sclerotic or mixed appearance. Tuberculosis involves adjacent vertebrae with invariable involvement of intervening disc. Primary bony neoplasm or plasmacytoma are mostly unilocular lesions and will show post-contrast enhancement. LCH usually presents as vertebra plana in the pediatric age group and mostly recovers independently. As the future prospective in MRI imaging, various quantitative parametric studies are available such as diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), and T2 relaxometry. On 3Tesla MRI imaging, T1-weighted images depict less noticeable changes in the signal intensity associated with the spinal injuries; however, they still reveal the injury site’s location. Signal-intensity changes are more conspicuous on the conventional T2-weighted images, with edema locating the site of spinal canal injury. Image post-processing of DWI, DTI, and T2 relaxometry allows the measurements of apparent diffusion coefficient (ADC), fractional anisotropy (FA), and T2 maps, respectively. The regions of interest are overlaid onto the anatomic images and show changes in signal intensity associated with spinal canal injury. In general, a decrease in signal intensity in FA with an increase in signal intensity on DWI and an increase in T2-weighted relaxometry denote the location of the spinal canal injury because of loss of nervous tissue organization.[7] Accurate diagnosis is a must in the case of a hydatid cyst of the spine, as is the detailed anatomical depiction of surrounding anatomy for surgical management. MRI provides meticulous details about the cyst, its content, and surrounding anatomical structures, thus assisting in correctly managing the disease. MRI also helps to exclude the close differential diagnosis. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.