|LETTER TO THE EDITOR
|Year : 2016 | Volume
| Issue : 4 | Page : 603-604
Primary cerebral hydatid cyst: An unusual cause of very slowly progressive hemiparesis in a child
Rajaraman Kartikueyan1, Sachinkumar Maheshbhai Patel1, Arijit Chattopadhyay2, Prasad Krishnan1
1 Department of Neurosurgery, National Neurosciences Centre, Peerless Hospital Campus, Kolkata, West Bengal, India
2 Department of Pediatric Neurology, National Neurosciences Centre, Peerless Hospital Campus, Kolkata, West Bengal, India
|Date of Web Publication||18-Aug-2016|
Department of Neurosurgery, National Neurosciences Centre, 2nd Floor, Peerless Hospital Campus, 360, Panchasayar, Garia, Kolkata - 700 094, West Bengal
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Kartikueyan R, Patel SM, Chattopadhyay A, Krishnan P. Primary cerebral hydatid cyst: An unusual cause of very slowly progressive hemiparesis in a child. J Neurosci Rural Pract 2016;7:603-4
|How to cite this URL:|
Kartikueyan R, Patel SM, Chattopadhyay A, Krishnan P. Primary cerebral hydatid cyst: An unusual cause of very slowly progressive hemiparesis in a child. J Neurosci Rural Pract [serial online] 2016 [cited 2019 May 22];7:603-4. Available from: http://www.ruralneuropractice.com/text.asp?2016/7/4/603/188621
Hydatid cyst, the cystic larval stage of Echinococcus granulosus (dog tapeworm), occurs in humans following accidental ingestion of eggs released from the intestine of the definitive hosts (canines). These eggs then hatch in the intestine into hexacanth embryos that penetrate the intestinal wall and enter the portal circulation.
A 5-year-old girl presented with gradually progressive right hemiparesis over 1½ years. Magnetic resonance imaging (MRI) of the brain showed a single large (8 cm × 7 cm × 7 cm) lesion hypointense on T1 and fluid attenuation inversion recovery sequences and hyperintense on T2 sequences. It was well marginated with no perilesional edema, not enhancing on contrast and was causing mass effect on the ventricle with midline shift. Subfalcine herniation was noted. The lesion had a T2 hypointense wall at its periphery. Hydatid disease was suspected [Figure 1]a and [Figure 1]b. Ultrasonography of the abdomen and chest X-ray were normal. The patient underwent left frontoparietal craniotomy, transsulcal approach and en masse removal of the cystic lesion and its coverings using the Dowling technique (instilling saline between the cyst and brain parenchyma and delivery). There was no intraoperative rupture. The lesion was lined by a milky-white thicker outer layer and an extremely thin transparent inner layer containing fluid and some particulate matte [Figure 1]c. Histopathology showed an acellular outer lamellated layer and an inner germinal layer containing multiple papillary projections with brood capsules containing multiple scolices with distinct hooklets [Figure 1]d. The postoperative period was uneventful with resolution of hemiparesis and computed tomography scan showed good brain expansion with no residual cyst. The patient was put on antihelminthics to treat any occult cysts that may have been undetected. Cardiac evaluation done postoperatively showed no evidence of patent ductus arteriosus or patent foramen ovale.
|Figure 1: (a) Axial fluid attenuation inversion recovery sequence showing a left hemispheric cystic hypointense lesion with no perilesional edema; (b) coronal T2 sequence showing the lesion is hyperintense with a well-defined margin and is causing mass effect and subfalcine herniation; (c) specimen removed intact with part of the thicker outer membrane peeled off showing a transparent thinner inner membrane with particulate matter and (d) microscopic picture showing a lamellated ectocyst (green arrows) and a thinner germinal layer (blue arrows) with brood capsules containing multiple scolices with hooklets (red stars) indicating the cyst is a primary one|
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Cerebral hydatid cysts are exceedingly uncommon and account for only 1–4% of all patients infected with Echinococcus. Although they can occur anywhere in the brain, they are most commonly found supratentorially in the middle cerebral artery territory. Seeding of the brain is usually secondary to a ruptured cyst elsewhere in the body that releases scolices in the blood stream. Such secondary cysts are sterile and have no brood capsules or daughter cysts inside., Surprisingly, though, in our case, though the cyst was a primary one, i.e. fertile with secondary cysts inside. This is uncommon  as the liver and lung usually filter the oncospheres that enter the portal circulation  and further this patient had no evidence of a right to left intra- or extra-cardiac shunt.
As in this case, intracerebral hydatid cysts occur more commonly in children than adults (50–93% are seen in children). They can attain a considerable size by the time they are diagnosed. Their rate of expansion may vary between 1.5 and 10 cm per year and hence a significant time lag may occur between the time of infection and onset of clinical symptoms., Children tend to present with features of raised intracranial pressure. Our case, though, had focal neurological deficits - A finding more common in adults. The differential diagnosis on imaging in such cases would include porencephalic cysts, cystic tumors, and intracerebral arachnoid cysts. However, lack of reactive changes in adjacent parenchyma and hypointense rim on T2 imaging are clues to the diagnosis.
Surgical removal is the preferred treatment of hydatid cysts  and these should ideally be removed into with all layers intact. Contamination of the operative field by cyst fluid predisposes to anaphylaxis and recurrence and must be avoided.,, However, in large cysts where cortical damage would be likely if en masse removal is attempted - cyst puncture, aspiration of fluid, instillation of hypertonic saline (a scolicidal agent), reaspiration and finally removal is an acceptable alternative.
In conclusion, though cerebral hydatid cysts are uncommon, even in endemic zones, they must be regarded as a differential diagnosis in children with a cystic intracranial space occupying lesion. Absence of perilesional edema, lack of mural nodule or wall enhancement on contrast, hypointense margin on T2 imaging (halo sign) and fluid contents being isointense to cerebrospinal fluid in all sequences on MRI must alert the clinician to this possibility as also a history of very slow progression which is unlikely in a neoplastic lesion. Despite the presence of barriers to prevent the entry of larvae into the systemic circulation, primary cerebral hydatid cysts may occur and since they cannot be differentiated from secondary sterile cysts on imaging, in all cases undergoing surgery attempt must be made to remove them without rupturing the wall and spilling the contents.
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| References|| |
Limaiem F, Kchir N. Hydatidosis of the brain. In: Turgut M, editor. Hydatidosis of the Central Nervous System: Diagnosis and Treatment. New York: Springer; 2014. p. 61-70.
Coates R, von Sinner W, Rahm B. MR imaging of an intracerebral hydatid cyst. AJNR Am J Neuroradiol 1990;11:1249-50.
Gupta S, Desai K, Goel A. Intracranial hydatid cyst: A report of five cases and review of literature. Neurol India 1999;47:214-7.
Reddy DR. Managing cerebral and cranial hydatid disease. Neurol India 2009;57:116-8.
Umerani MS, Abbas A, Sharif S. Intra cranial hydatid cyst: A case report of total cyst extirpation and review of surgical technique. J Neurosci Rural Pract 2013;4 Suppl 1:S125-8.