A Parasellar Hydatid Cyst Extending to the Opticocarotid Triangle, Pediatric Case
Article information
Abstract
The causes of sudden vision loss in one eye include isolated eye diseases, vascular pathologies, and optic nerve compression. This report highlights a case of parasitosis (Echinococcus granulosus) causing sudden vision loss due to optic nerve compression. To our knowledge, this is the first reported case of a hydatid cyst extending into the optic canal through opticocarotid triangle in a pediatric patient. A 12-year-old girl presented to the ophthalmologist with progressive visual deterioration over a period of 1 week. Examination revealed reduced visual acuity in her right eye. No ocular abnormality was detected on examination, cranial imaging revealed a lesion compressing the right optic nerve and the patient was referred to neurosurgery. The bright white lesion with a microscopic appearance resembling an epidermoid tumor was completely excised after aspirating the contents with transcranial access. Pathology was reported as hydatid cyst. Hydatid cysts invading the optic canal should be considered in the differential diagnosis of sudden visual loss in the pediatric age group; however, it continues to be an important health problem in developing countries. Meticulous excision of the cyst capsule without rupture ensures the success of surgical treatment.
INTRODUCTION
Hydatid cyst disease, caused by Echinococcus granulosus, is a parasitic infestation that predominantly affects the liver and lungs, with cerebral involvement being exceedingly rare, accounting for only 1–2% of all cases worldwide. This condition is most prevalent in sheep and cattle-raising regions, particularly in Mediterranean countries. Cerebral hydatid disease is especially uncommon, with most cases occurring in children through transmission via contaminated food or direct contact with infected animals. In addition to the rarity of intracranial hydatid cysts, parasellar localization is extremely rare and has been reported in cases. Imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI) play a crucial role in diagnosis, typically revealing hypodense, cystic lesions with minimal surrounding edema. The primary goal of treatment is the complete surgical removal of the cyst without rupture to prevent recurrence or severe inflammatory reactions [1,2,8].
In our case report, we present a pediatric patient with unilateral visual impairment due to extension from the cavernous sinus to the optic canal.
CASE REPORT
A 12-year-old girl presented to the ophthalmology clinic with visual impairment on the right side within a week. No ocular pathology was detected in the examination. Intracranial imaging showed a cystic lesion extending from the right cavernous sinus into the right optic canal, compressing the optic nerve and the patient was referred to neurosurgery. Other cranial nerve examinations were normal except for visual problems. The patient had no history of dog bites and lived in a village where his family was engaged in animal husbandry, and the region where he lived was endemic for hydatid diseases.
Radiology
Cranial MRI revealed a hyperintense lesion on T2-weighted images, and a capsular constricted lesion on contrast-enhanced T1-weighted images, with no evidence of diffusion restriction (Fig. 1A-D). The patient’s childhood age, parasellar cystic lesion and visual findings suggested craniopharyngioma as the preliminary diagnosis. Brain CT revealed a well-circumscribed, hypodense lesion with no calcification (Fig. 1E).
Image of hydatid cyst on cranial MRI and CT. A : In the contrast-enhanced T1-weighted MRI axial image, the yellow star indicates the optic nerve and the red triangle indicates the portion of the cyst extending toward the optic canal orifice. It can be seen that the cystic component is hypointense and the capsule is enhanced. B : Similarly on the sagittal T2-weighted sequence, the red triangle indicates the optic nerve and the portion of the cyst extending toward the optic canal orifice. C and D : DWI and ADC map showed no diffusion restriction. The borders of the cyst are shown with a dashed red circle. E : Brain CT shows a hypodense cyst with no calcification. The borders of the cyst are shown with a dashed red circle. F : On the T2-weighted coronal MRI image, the yellow dashed line delineates the cyst, while the red dashed lines indicate the ICA. It is observed that the cyst displaced the right ICA inferiorly. GR : gyrus rectus, ON : optic nerve, TL : temporal lobe, SS : sphenoid sinus, ICA : internal carotid artery, MRI : magnetic resonance imaging, DWI : diffusion weighted imaging, ADC : apparent diffusion coefficient, CT : computed tomography.
Surgery
After performing a right pterional craniotomy and drilling the anterior clinoid process extradurally, the dura was opened, and the cyst was accessed. The part adherent to the optic nerve and extending towards the optic canal orifice was explored. As demonstrated in Fig. 1F, the cyst’s displacement of the right internal carotid artery (ICA) inferiorly resulted in the ICA being initially obscured from the surgical field. Since the part extending into the optic canal is highly adherent to the optic nerve and has a narrow range of motion, the transparent, low viscosity fluid, which is the cyst content, was first aspirated and sampled (Fig. 2A-C). Subsequently, the cyst wall was separated from the optic nerve by sharp and blunt dissection without damaging the nerve. The entire cyst wall was excised completely (Fig. 2D). After the operation, his vision in his right eye improved.
Intraoperative images of optic nerve and cyst. A : Magnification under the microscope shows the anatomical relationship between the optic nerve and the cyst. B and C : Nerve hook is inserted into the optic canal and the cyst is dissected from the nerve. D : Macroscopic view of the total excised cyst. HC : hydatid cyst, ON : optic nerve, NH : nerve hook.
Pathology
Histopathologically, eosinophilic staining, non-nucleated, acellular lamellar cuticular membrane was observed. Scolex structure and germinative membrane were also observed (Fig. 3).
Pathologic staining images of hydatid cyst. A : H&E stained preparation; eosinophilic stained, nucleus-free, acellular lamellar cuticle layer. In addition, inflammatory reaction with fragmented leukocytes (×10). B : H&E stained preparation; germinative membrane and organism compatible with scolex in the lumen (×10). H&E : Hematoxylin A B and Eosin.
DISCUSSION
Sellar and parasellar localized hydatid cyst cases have been reported in the literature. Kireşi et al. [6] reported that parasellar localized hydatid cysts may occur in three forms : cranial, cranial extradural and combined. They explained the rarity of extradural forms with the limited blood flow to that compartment. Similarly, there are few extradural cases in the literature [6]. Guo et al. [3] reported two cases of parasellar hydatid cyst. In the first case, a 7-year-old patient presented with complaints of diplopia and ptosis and in the second case, a 21-year-old patient presented with complaints of visual loss and diplopia and were operated. Radiologic examinations revealed that the cysts compressed the temporal lobe, cavernous sinus and brain stem [3]. Behari et al. [1] reported a case of parasellar hydatid cyst infected after suppurative otitis media. Ophthalmoparesis and other examination findings associated with otitis media were found in this case. A favorable response was obtained with medical and surgical treatment. In this case, it was observed that the cyst capsule was adherent to the dura similar to our case [1]. Diplopia and other cranial nerve findings facilitate the diagnosis. Ozgen et al. [7] reported a case of isolated sellar hydatid cyst. In this case, hypopituitarism was found in an 18-year-old patient, but no findings were found on ophthalmologic examination. This case was operated by transsphenoidal method [7]. In our case, hypopituitarism findings were not observed. Kanpolat et al. [5] reported a hydatid cyst located in the cavernous sinus. In this case, bilateral papilledema was found in the patient. The patient also developed hemiparesis due to a second hydatid cyst in the motor cortex [5]. Rivierez et al. [9] reported a similar case of cavernous sinus hydatid cyst. Ophthalmoplegia and facial hypoesthesia were found in this case [9]. Gurha et al. [4] reported a 15-year-old boy with cysticercosis localized in the optic canal. In this patient, a cystic lesion was observed in the left optic canal and treated by transcranial approach [4]. In our case, although cavernous sinus was involved, other cranial nerve findings were not observed. No cases of hydatid cyst extending into the optic canal have been reported. In cases with only visual loss and ophthalmoparesis, the diagnosis may be difficult and delayed. In our case, the ophthalmologist’s referral to cranial imaging accelerated the diagnosis and treatment process.
CONCLUSION
We report the first case of parasellar pediatric hydatid cyst extending into the optic canal. In underdeveloped and developing countries, considering the age of the patient and the localization of the cyst, always considering parasitosis in the differential diagnosis will be beneficial in diagnosis and treatment.
Notes
Conflicts of interest
No potential conflict of interest relevant to this article was reported.
Informed consent
Informed consent was obtained from the parents of the patient.
Author contributions
Conceptualization : MCK; Data curation : MCK, AD; Formal analysis : MCK, AD; Funding acquisition : MCK, AD; Methodology : MCK; Project administration : MCK, AD; Visualization : MCK; Writing - original draft : MCK; Writing - review & editing : MCK, AD
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