Largest intracranial calcified hydatid cyst: A case report with review of literature

Cerebral hydatid disease is a peculiar manifestation of echinococcosis, an infection acquired from Echinococcus tapeworm, in its larval stage. It symbolizes only 2% of all the cerebral space occupying lesions. It is frequently observed in children and young adults. In this paper, we report an exceptional case of intracranial solitary calcified hydatid cyst in a 25 year old male, shepherd by occupation, presenting with history of difficulty in walking and convulsions for the last 20 years. Craniotomy was carried out and an intact calcified mass weighing around 300 grams was excised. It is the largest intracranial calcified hydatid cyst excised till date and is first of its kind.

Key-words:

Calcified - echinococcosis - hydatid cyst - intracranial

Introduction

Hydatid disease, a cyclo-zoonotic infection induced by Echinococcus tapeworm, a larval form. In humans, the two predominant variety of hydatid disease are caused by Echinococcus multilocularis, and Echinococcus granulosus.[[1]] Cerebral hydatid disease is infrequently observed, even in the endemic areas, depicting only 2% of all cerebral space occupying lesions.[[2]] Infestation with E. multilocularis frequently leads to calcification, but is rarely observed with incidence being <1% of all the intracranial hydatid cysts. In the Indian subcontinent, it is prevalent in Tamil Nadu, Andhra Pradesh, and Punjab.[[2]],[[3]] In the present article, we report an exceptional case of largest solitary calcified cerebral hydatid cyst (~25.4 cm in diameter) in a young male with detailed review of literature.

Case Report

We present a case of a 25-year-old male patient, shepherd by occupation, native of Balaghat, Madhya Pradesh. He presented to our clinic with complaints of difficulty in walking and convulsions for the past 20 years. For all these years, he was being treated by a local physician and was misdiagnosed as a case of poliomyelitis. Neurological examination had revealed muscle wasting and contracture of both limbs on the right side. Power was grade four. Speech and vision were normal. No other deficit was found. A noncontrast computed tomography (CT) of the brain revealed a well-defined spherical nonenhancing, hypodense, well-circumscribed, peripherally calcified 7 cm × 8 cm size space occupying lesion in the left frontoparietal region [[Figure 1]]. A contrast-enhanced magnetic resonance imaging (MRI) of the brain revealed nonenhancing intra-axial focal lesion with calcified walls [[Figure 2]]a and [[Figure 2]]b. No restriction on diffusion was observed. Cyst wall appeared hypo-intense in all sequences with blooming area, suggestive of calcification. No perilesional edema was seen. Complete work-up of the patient was done but there was no presence of primary disease in other organs. The patient was operated with frontoparieto-temporal craniotomy. The mass was totally calcified and loosely adherent to dura matter. Through simple dissection, mass was excised in one piece without rupture and spillage. The weight of the cyst was around 300 g [[Figure 3]]. The longest and shortest diameter of the cyst were 25.4 cm and 23.9 cm, respectively [[Figure 4]]a and [[Figure 4]]b. The cavity was then irrigated with hypertonic saline jet. Ventricle was incidentally punctured leading to spilling of cerebrospinal fluid. Dura was closed primarily. There was no postoperative new neurological deficit. Histopathological examination revealed calcified hydatid cyst. The patient was discharged on 10th postoperative day after removal of the sutures and was prescribed tablet albendazole 400 mg BD for a month and advised regular follow-up.

Figure 1: Computed tomography scan showing left frontoparietal mass (7 cm ˣ 8 cm) with perilesional calcification

Figure 2: (a) T1-weighted magnetic resonance imaging shows images showing the left cystic mass with hypointensity in the posterosuperior wall consistent with perilesional calcification (b) T2-weighted magnetic resonance imaging shows nonenhancing intra-axial focal lesion with calcified wall

Figure 3: Weight of calcified hydatid cyst (~300 grams)

Figure 4: Dimensions of calcified hydatid cyst (a) Longest diameter of the cyst ~25.4 cm (b) Shortest diameter of the cyst ~23.9 cm

Discussion

Hydatid cyst frequently involves liver (75%) followed by lung (15%). However, central nervous system is involved in only 1% of the cases. It is generally diagnosed in children and young adults. Cyst can be located anywhere in the brain, but is usually found in the supratentorial compartment, supplied by the middle cerebral artery. Parietal region is most frequently affected, followed by the frontal region.[[2]],[[4]]

Cerebral hydatid cysts can be categorized as primary and secondary. The primary hydatid cysts grows as a result of the direct infestation of larvae in the brain, devoid of evidence of disease in other organs. Primary cysts incorporates scolices and brood capsules, thus are fertile and can lead to recurrence on rupture. Secondary hydatid cysts do not have brood capsule and scolices. They arise due to traumatic, spontaneous, or surgical rupture of primary hydatid cyst. They are infertile and thus, the chances of recurrence, as a result of rupture, are minimal.[[5]]

Hydatid cyst starts producing symptoms only when they attain a large size. Its location is responsible for the appearance of the various symptoms. Majority of patients present with headache and vomiting.[[6]] Almost all the cases of calcified hydatid cyst described in the literature presented with convulsions.[[4]] Similarly, our patient had a history of convulsion for the past 20 years.

Imaging techniques such as CT and MRI are diagnostic of intracranial hydatid cyst. CT is suitable for distinguishing the cyst calcification, whereas cyst capsule is best demonstrated by MRI. In addition, MRI is beneficial in preparation of the patient for the surgery.[[2]] However, histopathological examination forms the major basis for making the specific diagnosis of hydatid disease. Serological tests are commonly negative, when the cyst is calcified.[[7]]

The differential diagnosis of intracranial hydatid cyst involves arachnoid cysts, porencephalic cysts, pyogenic abscess, and cystic tumor of the brain. Arachnoid cysts are not round in shape, are not covered by the brain tissue, and remain extra-axial. Porencephalic cysts are usually due to trauma to the normal brain parenchyma and are covered with white matter. Cystic tumors often have enhancement of soft-tissue components on imaging. Cerebral abscess show distinct central necrotic area, peripheral edema, and satellite lesions.[[2]],[[8]]

Primary treatment of hydatid cyst is surgical. The most desired procedure is Dowling technique. It includes Valsalva maneuver, gravity assisted removal of the cyst from the corticectomy site, and breaking the adhesions between brain parenchymal tissue and cyst wall with the help of hypertonic saline jet. Different surgical problems encountered includes extraction of the intact cyst to arrest the rupture, anaphylaxis, and recurrence of the cyst.[[9]] Known postoperative complications includes obstructive hydrocephalus and subdural effusion. Chief reason of mortality during the procedure is anaphylactic reaction, as a result of the cyst rupture.[[8]]

Albendazole in the form of drug treatment may be used for small multifocal cysts and presurgically to reduce the size of a large cyst. It is recommended as a four 1-month courses, with 15 days drug free intervals, in a dose of 10–15 mg/kg/day. It is parasiticidal and acts by blocking the uptake of glucose by larvae and adult parasites.[[8]],[[10]]

Our patient's case is unique in a sense that there was a presence of long standing history of complaints coupled with misdiagnosis, as a case of poliomyelitis, and intracranial solitary calcified hydatid cyst weighing 300 g, which is rare in the literature and first of its kind in India. Hydatid cyst in the brain without its presence in other organs has not been fully explained in the literature. This case is, thus, a primarily intracranial calcified hydatid cyst, a condition rare in adults.

Conclusion

An intracerebral calcified hydatid cyst is a rare entity with very few cases reported in literature. Hydatid disease should be considered when there is the presence of calcification and absence of contrast enhancement and perilesional edema during CT brain, in patients living in endemic or nonendemic areas.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Conflict of Interest

There are no conflicts of interest.

Financial support and sponsorship

Nil.

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Publication History

Received: 07 April 2020

Accepted: 11 June 2020

Article published online:
16 August 2022