Orbital hydatid cyst in childhood: a report of two cases.

Abstract: Intraorbital hydatid disease (IHD) is quite rare and represents < 1% of the Echinococcus cases. In our current communication, we report two children with solitary, primary intraorbital hydatid cysts. Both children presented with nontender, nonpulsatile proptosis. Imaging workup, including CT and MRI scans of the head and the orbits, revealed a retro-bulbar cyst in both patients. Surgical resection was performed by employing a fronto-temporo-orbito-zygomatic (FTOZ) approach. Accidental intraoperative rupture occurred in one case with no further consequences. Albendazole was postoperatively employed for 12 weeks. Outcome was excellent in both cases with complete resolution of their symptoms and complete visual recovery. Pertinent literature was reviewed with this opportunity.

Key Words: albendazole, exophthalmos, hydatid cyst, orbital, outcome

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Echinococcosis represents one of the most common human parasitoses in certain geographical areas; its incidence, clinical manifestations, outcome and treatment have been adequately described in the literature. (1) Although liver and lungs are usually involved in the vast majority of cases, the presence of hydatid cysts in other organs has also been extensively reported. (1) The incidence of orbital hydatid disease has been reported to range from 0.3% to 1.0% among patients with Echinococcosis, while in highly endemic areas orbital hydatid cysts represent 5 to 18% of patients referred to hospitals with ocular orbital space occupying lesions. (2-7) Increased migration and world-wide traveling have made the detection of orbital hydatid cyst cases possible in geographical areas such as Northern America and Northern Europe.

In our current communication we present two cases of orbital hydatid cysts in children, and with this opportunity, we review the pertinent literature regarding the diagnosis and the therapeutic management of patients harboring orbital hydatid disease.

Case Report

Patient 1

A 15 year old girl was admitted to the neurosurgical service with severe proptosis of the left eye after sustaining a minor head injury 48 hours earlier. Her physical examination revealed moderate left eye proptosis, which according to the patient was firstly noted approximately two weeks ago. Her left eye was non tender to palpation while no bruits were audible. Ocular motion was within normal limits. Fundoscopic examination revealed left-sided Grade II pupillary edema. A head CT scan was obtained, which showed a well-defined, round, hypo-dense mass with a peri-lesional rim of hyperdensity; the adjacent bony structures appeared intact (Fig. 1). A MRI study demonstrated a homogeneous unilocular lesion, which was hypointense on T1 weighted images and hyperintense on T2 weighted images (Fig. 2).

At that point, systemic diagnostic workup thought to be necessary for ruling out disseminated hydatidosis. This included thorax and abdominal CT scans as well as echocardiogram. All of the obtained studies revealed no abnormalities. Surgical resection via a left-sided Fronto-Temporo-Zygomatic (FTOZ) craniotomy was undertaken, and with employing microsurgical dissection, the external capsule of the cyst was dissected from the intraorbital structures and the cyst was resected en toto.

No intraoperative or postoperative complications occurred. A postoperative CT-scan confirmed extirpation of the cyst (Fig. 3). Postoperatively, Albendazole (10 mg/kg twice a day) was administered to the patient for 12 weeks.

The patient was followed for 2 years. Her left-side proptosis was totally resolved within 2 weeks postoperatively, and her fundoscopic examination returned to normal within 6 weeks postoperatively. She remained totally asymptomatic, and she was finally discharged from our outpatient clinic.

Patient 2

A 4 year old male was admitted to the neurosurgical service with symptoms of progressive axial proptosis of the left eye and visual disturbances of four week duration. His physical examination revealed a non tender to palpation left eye proptosis, which was nonpulsatile; ipsilateral IVth and VIth nerve paresis was also noted. The rest of his physical examination was unremarkable.

Head and orbital CT and MRI scans were obtained revealing a moderate size cyst within the left orbital cavity, which was compressing and was anteriorly displacing the ocular globe; the cyst demonstrated homogenous intensity and there was no contrast enhancement (Fig. 4). The rest of his imaging workup, including cardiac echo and thorax and abdominal CT-scans, revealed no other lesions.

The patient underwent surgical resection of the retrobulbar cyst via a left FTOZ approach. Intraoperatively, the outer capsule of the exposed cyst was identified, and an effort was made to dissect it from the adjacent, tightly-adherent neural structures. During the micro-dissection, a tear of the outer membrane occurred, with subsequent cystic fluid leakage. The operative field was thoroughly irrigated with 9% hypertonic saline solution, while the cystic content was meticulously removed. The cyst membrane was dissected and finally, completely removed (Figs. 5 & 6).

The patient was maintained on Albendazole (10 mg/kg twice daily for 12 wk) and his postoperative period was uneventful. His clinical examination improved with total resolution of his preoperative proptosis and cranial nerve pareses within three months postoperatively. His follow-up (3 years) revealed no other complications or any other systematic lesions, while the patient remained totally asymptomatic and was finally discharged from our outpatient clinic.

Discussion

Orbital hydatidosis represents a quite rare clinicopathologic entity. (2-7) It can be differentiated to primary, where cyst or cysts are solely located into the orbital cavity (as in our cases) and secondary, when orbital lesions represent a component of disseminated multi-organ systemic disease. (8,9) Its incidence varies from 0.8 to 1.0% of all hydatid disease cases, but in highly endemic areas, orbital hydatid cysts have been reported to represent up to 25.8% of all cystic orbital lesions. (2-7,10,11) Orbital Echinococcal cysts are significantly more common in children (12-15); however, cases of elderly patients with isolated primary orbital cysts have been reported. (16-19) Orbital hydatid cysts are solitary lesions in the vast majority of cases, but there are reports in the literature of multiple intraorbital cysts, a phenomenon which occurs in less than 5% of patients with orbital hydatid cysts. (7) The usual strains responsible for orbital cysts are E granulosus and E multicularis, although E oligarthrus has been isolated in cases from South and Central America. (1,20,21)

Even though intraorbital hydatid cyst is quite rare, especially in nonendemic areas, it should always be included in the differential diagnosis of orbital space-occupying lesions. The most commonly presenting clinical symptoms and signs of orbital Echinococcosis are: nonpulsatile, nontender exophthalmos (as in our cases), visual disturbances, papilledema, diplopia, chemosis, eyelid edema, conjunctivitis and hypopyon. (22) The mean duration of symptoms has been reported to vary between 3 months and 2 years. (23) In our cases, the duration of symptoms was less than 4 weeks. There are reports in the literature, mostly from developing countries, in which patients presented at very late stages of their disease with subsequent unfavorable outcome. (24,25) However, a few cases with acute onset visual acuity loss have been reported, due to retinal detachment. (26,27) Exudative retinal detachment can be explained on the basis of toxins liberated from the semipermeable cyst wall, causing local inflammation. (27)

In regards to the anatomic location of the intraorbital hydatid cysts, various orbital locations have been described. (4,28-36) It is well accepted that there is a predilection for the superomedial and superolateral orbital areas. (37) More uncommon locations, such as within the medial rectus muscle, subretinally in the vitreous body in the anterior chamber, (29) and retro-orbitally (35) have also been reported. Interestingly, Talib, in his report, stated that left-sided lesions were more common than right-sided ones; due to the fact that left, common carotid artery arises directly from the summit of the aortic arch. (3) Another interesting observation is the presentation of several cases in association with a minor head injury, as in one of our cases. (17) This association might be explained by the fact that the sustained head injury alarms the patients and their families and makes them seek medical help so their long-standing ocular symptoms are discovered; however, etiologic association cannot be ruled out.

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The diagnostic imaging approach of these lesions has been thoroughly investigated and adequately described in previous series. (13,29,32,37-39,40-42) However, the absence of the "water-lily" sign in the orbital cysts, which represents a typical characteristic of the Echinococcal cysts in other locations, is a point that needs to be emphasized; there is only one orbital case reported with a positive "water-lily" sign. (42) The superiority of the MRI in the detection of the lesion and the delineation of its relationship to the adjacent ocular structures cannot be overemphasized. (29,32,38) It is also widely accepted that none of the currently employed serologic tests can rule out the existence of a solitary orbital hydatid cyst. (3,17,38,43)

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In regards to the selection of the most appropriate surgical approach for resecting an orbital hydatid cyst, several reports exist in the literature. (5,9,44-46) Each approach carries certain advantages and disadvantages. The size of the cyst, its anatomic location, its extension into the cranial cavity, the patient's general medical condition, the extent of the disease and the surgeon's familiarity with each surgical approach are a few among other factors that will dictate the most suitable approach. We selected the FTOZ approach in our cases because it provides adequate exposure for meticulous microsurgical dissection of the cyst and is very frequently employed in our department in comparison to some purely orbital approaches. The major disadvantage of this approach is the risk of intraoperative cyst rupture and spillage of its content into the cranial cavity. Meticulous microsurgical dissection, continuous irrigation during dissection and adequate visualization are key elements in successful extirpation of these cysts. Postoperative adjuvant chemotherapy with albendazole is recommended by previous reports. (7,47) The outcome of these procedures has been reported excellent in the vast majority of cases (4,5,44,45); however, in late stage cases with extensive optic atrophy and global compression, enucleation of the globe has been reported. (24,25,48)

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The early diagnosis of orbital hydatidosis and its prompt surgical management has excellent results in the vast majority of these patients. This makes the importance of its appropriate diagnosis even more crucial. The clinician should always include the diagnosis of hydatid cyst in the differential diagnosis list of orbital mass, especially in children. Increases of world tourism and migration should make the clinician to include this quite rare diagnosis in his list even in nonendemic areas.

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Alexandru Vlad Ciurea, MD, Gambardella Giuseppe, MD, Theofilos G. Machinis, MD, Teodora Camelia Coman, MD, and Kostas N. Fountas, MD, PHD

From the Department of Neurosurgery, Clinic Hospital, Bagdasar-Arseni, Bucharest, Hungary; the Department of Microsurgery, Hospital Casa Di Cura Cristo Re, Messina, Italy; and the Department of Neurosurgery, The Medical Center of Central Georgia, Mercer University School of Medicine, Macon. GA.

Reprint requests to Kostas N. Fountas, 840 Pine Street, Suite 880, Macon, GA 31201. Email: [e-mail]

Accepted February 24, 2006.

RELATED ARTICLE: Key Points

* Orbital hydatid cyst represents a quite rare location of Echinococcosis.

* Orbital cysts occur most commonly in children.

* Early detection and prompt surgical resection of these orbital cysts result in excellent functional outcome in most patients.

* Albendazole is recommended as an adjunctive treatment.

* Inclusion of orbital hydatid cyst in the differential diagnosis of orbital mass is of paramount importance for their prompt treatment.