Isolated cerebellar hydatid cyst in a child: a rare case report

Abstract

Introduction:

Hydatid disease is a parasitic infection caused by Hydatid disease, most commonly involving the liver and lungs. Intracranial hydatid cysts are rare, representing only 1–2% of cases, and posterior fossa localization is exceptional.

Case presentation:

We present a 7-year-old girl with a 1-month history of headache, 1 week of fatigue, and 3 days of vomiting and fever. Examination revealed lethargy and a thready pulse. MRI and CT showed a retrocerebellar cyst compressing the cerebellum with obstructive hydrocephalus. Emergency craniotomy was performed, and the cyst was excised intact. Histopathology confirmed a hydatid cyst. The patient recovered well and was discharged without complications.

Discussion:

Posterior fossa hydatid cysts are exceedingly rare and often misdiagnosed as more common pediatric cystic lesions. Imaging can strongly suggest the diagnosis, but histopathological confirmation remains the gold standard. Surgery is the treatment of choice, with intact excision being essential to prevent recurrence and dissemination. Our case demonstrates the diagnostic challenge and emphasizes the importance of early suspicion in endemic regions.

Conclusion:

Although rare, cerebellar hydatid cysts should be considered in the differential diagnosis of pediatric posterior fossa cystic lesions in endemic areas. Early recognition, accurate imaging, and meticulous surgery are key to favorable outcomes.

Introduction

Hydatid disease, or cystic echinococcosis, is a parasitic infection caused by the larval form of Echinococcus granulosus, a tapeworm for which dogs and other carnivores act as definitive hosts^[1–4]. Humans acquire the disease accidentally through ingestion of eggs, usually via contaminated food, water, or direct contact with infected animals. Once ingested, embryos penetrate the intestinal wall and disseminate hematogenously to organs, forming cysts that grow slowly over years.

The disease predominantly affects the liver (50–70%) and lungs (20–30%), while involvement of the central nervous system (CNS) is extremely rare, reported in only 1–2% of cases^[1,2]. Intracranial hydatid cysts are more common in children and young adults, reflecting both higher exposure in endemic regions and greater vulnerability^[2–4]. Most are supratentorial, particularly in the parietal lobe, where blood flow distribution favors parasite lodging^[2,5]. By contrast, posterior fossa lesions, especially isolated cerebellar hydatid cysts, are exceedingly rare and pose a diagnostic challenge^[3].

HIGHLIGHTS

• Posterior fossa hydatid cysts are exceedingly rare in children and can mimic more common cerebellar lesions.

• Accurate imaging with CT and MRI is essential for diagnosis and preoperative planning.

• Meticulous surgical excision without cyst rupture is crucial to prevent recurrence and achieve optimal outcomes.

Clinically, cerebral hydatid cysts may present with headache, nausea, vomiting, visual disturbances, or seizures. Symptoms are largely related to raised intracranial pressure or mass effect, while focal neurological deficits depend on cyst location^[6,7]. Serology has limited diagnostic value for CNS disease, with sensitivities as low as 25–56%^[8,9]. Because clinical features are nonspecific, radiological imaging is indispensable. CT typically demonstrates a well-defined hypodense cyst without enhancement, while MRI better characterizes capsule and associated complications^[9]. Thus, definitive diagnosis is usually achieved intraoperatively or through histopathological confirmation^[5,10].

Surgical excision remains the treatment of choice, as medical therapy alone is insufficient to control intracranial disease^[2,8]. The challenge lies in achieving complete removal without rupture, since spillage may lead to recurrence and secondary dissemination^[8].

In this report, we describe a rare case of a 7-year-old girl with an isolated retrocerebellar hydatid cyst, emphasizing the diagnostic difficulties, surgical considerations, and the importance of early recognition in endemic areas.

Case presentation

A 7-year-old girl presented with a 1-month history of headaches, 1 week of fatigue and inactivity, and 3 days of fever and vomiting. She had no significant past medical history, surgical history, allergies, or family history of similar conditions.

On admission, vital signs were normal except for a thready pulse. Neurological examination revealed poor oral receptivity, difficulty in head extension, and a Glasgow Coma Score of 10/15. Tendon reflexes were responsive, with mild plantar flexion. Cardiac, chest, and abdominal examinations were otherwise unremarkable, though abdominal ultrasound incidentally revealed a horseshoe kidney and gallbladder microlithiasis.

Laboratory tests showed a WBC count of 8700/µl (lymphocytes 54%, neutrophils 37%), Hb 11 g/dl, platelets 328 000/µl, PT 81 seconds, PTT 29 seconds, and normal CRP.

MRI scans revealed a well-defined cyst in the left cerebellar hemisphere, causing compression of cerebellar structures and obstructive hydrocephalus as shown in Figure 1. No additional intracranial masses or hemorrhages were noted. Several cervical lymph nodes were identified but appeared reactive. No hepatic or pulmonary cysts were detected. No additional measures were taken to address the hydrocephalus as the patient underwent an immediate emergency craniotomy.

Figure 1.

Coronal MRI brain images demonstrating a well-defined, hyperintense cystic lesion in the posterior fossa, compressing the cerebellar hemisphere. The lesion appears bright on T2-weighted sequences, consistent with a cerebrospinal fluid–filled cystic process.

The patient underwent emergency posterior fossa craniotomy in the ventral recumbent position with the head slightly tilted to optimize surgical access. A mid-occipital skin incision was made, followed by careful dissection of subcutaneous tissue to expose the occipital bone. An occipital bone flap was elevated to provide adequate exposure of the cerebellar hemisphere.

The dura was opened in an X-shaped fashion, revealing the hydrocephalus-associated cyst in the left cerebellar hemisphere shown in Figure 2. The cyst was carefully separated from surrounding cerebellar tissue using meticulous blunt dissection. Saline irrigation was employed to create a gentle plane between the cyst wall and cerebellar parenchyma, minimizing traction and avoiding rupture. This technique is consistent with Dowling’s method for intact hydatid cyst excision^[2,8].

Figure 2.

Intraoperative images. Left: the tense, translucent cyst wall (yellow arrow) bulging over the cerebellar hemisphere after dural opening. Bottom right: a closer view of the intact hydatid cyst wall (yellow arrow) prior to dissection. Top right: the excised cyst, showing its smooth, glistening wall, after careful removal without rupture.

Once mobilized, the cyst was removed en bloc without spillage. Figure 2 shows the whole mass. Hemostasis was secured using bipolar cautery, and the dura was closed in a watertight fashion. The bone flap was replaced, soft tissues were sutured in anatomical layers, and a pressure bandage was applied. Analgesics and corticosteroids were administered postoperatively to control pain and cerebral edema. The excised cyst was sent for histopathology, which confirmed a retrocerebellar hydatid cyst without malignant features.

The patient tolerated the procedure well, with no intraoperative complications. Postoperatively, she remained neurologically intact and stable, with no seizures or signs of infection.

Postoperative recovery was uneventful. Repeat laboratory tests showed a WBC count of 20 000/µl, Hb 10.6 g/dl, and platelets 492 000/µl. The patient remained neurologically intact, afebrile, and without seizures. She was discharged with instructions to maintain wound care. A follow-up after 10 days showed no deficits or concerns with the surgical wound healing appropriately.

Discussion

Hydatid disease continues to be a public health concern in endemic regions such as the Mediterranean basin, the Middle East, South Asia, Latin America, and Australia, and sporadic cases are increasingly reported in non-endemic countries due to migration and global travel^[8]. Within the central nervous system, hydatid cysts are exceedingly rare, representing only 0.5–4% of space-occupying intracranial lesions^[6–8]. The vast majority occur in the supratentorial compartment, particularly the parietal lobes, while posterior fossa lesions are exceptional^[11]. This explains why our patient’s isolated cerebellar cyst represents an unusual manifestation that challenges clinical suspicion.

The rarity of posterior fossa hydatid cysts contributes to the diagnostic difficulties, as their clinical manifestations overlap with more common pediatric pathologies. Headache, nausea, vomiting, and gait disturbance are frequently seen in posterior fossa tumors of childhood, and seizures may further confound the picture when supratentorial lesions are considered^[2,4,6]. In our case, the presenting symptoms of headache, fatigue, vomiting, and reduced oral tolerance suggested raised intracranial pressure but were not specific for hydatidosis. Such non-distinctive features often result in misdiagnosis, as reported in the literature where cerebellar hydatid cysts have been mistaken for astrocytomas, arachnoid cysts, or epidermoid tumors^[2,11]. Therefore, awareness of hydatid disease in endemic areas is essential to avoid delays in management.

Radiological imaging plays a pivotal role in narrowing the diagnosis. CT scanning typically reveals a round, well-defined hypodense lesion with smooth walls and no contrast enhancement, features consistent with our case. MRI provides superior delineation of the cyst capsule, perilesional edema, and associated hydrocephalus, all of which were clearly identified in our patient^[9]. Despite these advances, radiology alone cannot always distinguish hydatid cysts from other cystic lesions of the posterior fossa, reinforcing the role of epidemiological context. Serological assays such as ELISA or complement fixation, though widely used for hepatic or pulmonary hydatidosis, are of limited value in CNS involvement, with sensitivities ranging between 25 and 56%^[8,9]. For this reason, our diagnostic reliance was primarily on CT and MRI, later confirmed by histopathological examination.

Management of intracranial hydatid cysts rests on complete surgical excision. Dowling’s technique, employing careful saline irrigation to separate the cyst from adjacent brain tissue, is widely regarded as the safest approach^[2,8]. The most critical surgical principle is removal of the cyst intact, as rupture may cause dissemination, anaphylaxis, and recurrence. Intraoperative rupture has been reported in up to 13% of cases, with a strong association with recurrence requiring adjunctive medical therapy such as albendazole^[8,12]. In our case, the cyst was removed intact, and the patient experienced an uneventful postoperative recovery, highlighting the importance of meticulous operative technique.

Postoperative complications reported in the literature include seizures, transient neurological deficits, and subdural fluid collections^[1,12]. Fortunately, our patient had no neurological deterioration, fever, or seizures after surgery or at follow-up, and was discharged in stable condition. The absence of systemic hydatidosis in the liver or lungs also emphasized the rarity of isolated cerebellar involvement.

In conclusion, this case reinforces the importance of maintaining a high index of suspicion for hydatid disease when evaluating pediatric posterior fossa cystic lesions in endemic regions. Despite its rarity, early recognition combined with modern imaging and careful surgery can result in excellent outcomes.

Conclusion

Posterior fossa hydatid cysts are an exceptionally rare manifestation of intracranial hydatidosis. In children presenting with posterior fossa cystic lesions in endemic areas, hydatid disease must be considered as a differential diagnosis. Accurate imaging and timely surgical excision without rupture are critical to achieving favorable outcomes and preventing recurrence.

Methods

This work has been reported in line with the SCARE criteria^[13].

Ethical approval

Ethical clearance was not required for the study as it involves a case report adhering to evidence-based medicine principles, with approval obtained locally from the Department of Neurosurgery.

Consent

Written informed consent was obtained from the patient’s parents/legal guardian for publication and any accompanying images. A copy of the written consent is available for review from the Editor-in-Chief of this journal on request.

Sources of funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author contributions

F.A.: conceptualization, investigation, original draft, editing, reviewing & bibliography; A.F.: original draft, editing & reviewing; M.A.J.: original draft, editing & reviewing; J.A.: original draft, editing & reviewing; J.A.: original draft, editing & reviewing; L.J.: original draft, editing & reviewing.

Conflicts of interest disclosure

The authors declare no conflict of interest.

Research registration unique identification number (UIN)

Not applicable.

Provenance and peer review

Not commissioned; externally peer reviewed.

Guarantor

Fares Abboud.

Data availability statement

All necessary details are available in the article. Further enquiries can be directed to the corresponding author.