Journal of Neuro-Ophthalmology, March 1992, Volume 12, Issue 1

Orbital hydatid cyst. Report of a case followed by serial computed tomography.

Journal of Cllllleal NCllro- Ol'hthalmo! ogy 12( 1): 43- 46, 1992. Orbital Hydatid Cyst Report of a Case Followed by Serial Computed Tomography Mehmet Turgut, M. D., Suleyman Saglam, M. D., and Osman Ekin Ozcan, M. D. "~ 1992 Raven Press, Ltd., New York A case of an orbital hydatid Cyst which showed recur­rence and regressed with antihelminthic therapy is de­scribed. Key Words: Orbital cyst- Hydatid cyst- EcilillOCOCCliS grallllloslis- Computed tomography, From the Department of Neurosurgery, Hacettepe University Hospitals, Ankara, Turkey, Address correspondence and reprint requests to Dr. Mehmet Turgut, Dokuzuncu Durak, Bakacak Sokak 19/ 2, Yenimahallel Ankara, Turkey. 43 Orbital hydatid cyst is very rare, while nonor­bital forms constitute a still frequently encountered disease in Turkey ( 1- 4), It has been stated that only 1% of all hydatid cysts are localized in the orbit ( 5), In 1982, two children with orbital hydatid disease were reported from our clinic ( 2). In this article, we report an additional case in whom we observed recurrence of the disease and in whom antihel­minthic therapy caused complete clinical and ra­diological regression on serial scans, CASE REPORT This 5- year- old boy was admitted to our clinic on March 28, 1987, with a progressive left- sided ex­ophthalmos that had started 9 months previously, From his history, we learned that his family were farmers and owned three sheep dogs, General physical examination on admission was unremarkable, On routine chest radiograph exam­ination, two well- circumscribed lesions, 1.5 cm in diameter, were observed on the right lung, Neuro­ophthalmological examination showed left- sided exophthalmos of 7 mm and papilledema, Visual acuity was 20/ 20 in the right eye, and 20/ 30 in the left eye, The left eyeball was pushed downward, outward, and forward, Upward, medial, and lat­eral ocular movements were limited on the left. The eyeball was nonpulsatile and nonreducible, Skull films were normal. Computed tomography ( CT) scan showed a nonenhancing oval cystic le­sion with a hyperdense rim within the muscle cone, The optic nerve was not identified, On CT, there was mass effect on the medial orbital wall and a septum running through the cyst ( Fig. 1). In April 1987, he was operated on at Pediatric Surgical Service for cysts in his right lung. Two weeks later, surgical intervention was performed 44 M, TURGUT ET AL FIG. 1. A well- circumscribed, low- density intraconal cyst with hyperdense rim on precontrast ( A) and postcontrast ( B) axial CT scans Note the septum ( small arrows) running through the cyst and slight bowing of the wall ( large arrows), through a transcranial approach in our clinic. An echinococcus cyst containing approximately 8 ml of hydatid fluid, located within the muscular cone, was removed. Unfortunately, it was ruptured due to poor location during the surgical intervention, Therefore, the surgical area was generously washed with hypertonic saline solution. Patholog­ical examination of the specimen was consistent with a diagnosis of EchillococClIS gralllllosliS infesta­tion. The patient was readmitted 7 months later be­cause of recurrent left- sided exophthalmos, Neuro- ophthalmological findings suggested an ex­panding lesion of the orbit. A repeat CT scan again showed growth of a cystic lesion with a thicker cavity wall in the left orbit located partially intra­conal ( Fig. 2), In view of the location of the lesion, the patient was treated with mebendazole, a an an­tihelminthic drug, for 10 months and remained well at follow- up, A CT scan in August 1988 showed a considerable reduction in size of the le­sion ( Fig. 3), and when repeated again in Decem­ber 1990, three years after the start of treatment, it showed almost complete resolution and resultant small calcified lesion ( Fig. 4). " The generic name of mebendazole is [ metil( S- benzoil benz­imidazol- 2- il) karbamat] . FIG. 2. Precontrast ( A) and postcontrast ( B) scans showing the recurrence of hydatid cyst which ruptured dUring first operation, with a thicker cavity wall. Again noted is the enlargement of the left orbit with bowing of the medial wall ( arrows), In addition, the left optiC nerve appears slightly swollen, ] Clin NCUlu-" phti'alll10L Vol 12. No, 1. 1992 HYDATID CYST OF THE ORBIT 45 FIG. 3. Follow- up CT scan. 9 months after the start of antihelminthic drug, demonstrates marked decrease in the size of the cyst. DISCUSSION Hydatid disease, a parasitic infectious disease caused by the larval stage of Echinococcus granulo­sus, is endemic in Turkey, ( 3) and it usually in­volves all three hosts of the epidemiological chain consisting of sheep, dog, and humans ( 16). Hu­mans are intermediate hosts; the parasite enters the host in childhood, because of the child's close contact with dogs, and it becomes symptomatic in following years. Although the hydatid cyst affects almost every organ in the body, it generally occurs in the liver and lungs. Orbital localization is rare ( 1). Clinical symptomatology, in general, is not di­agnostic ( 7) and immunodiagnosis of the hydatid cyst is always negative as well ( 6). At the present time, however, CT has advanced significantly the diagnosis and management of orbital lesions ( 7). The first case of an orbital hydatid cyst studied by CT was reported by Ozgen et al. ( 4). In the follow­ing years, orbital hydatid cysts have been reported with increasing frequency with the help of the CT scanner, especially from the Middle East ( 7,8), the Mediterranean Basin ( 1,6,9), and India ( 10). Its CT characteristics differentiate it from other intraor­bital space- occupying lesions. The CT appearance of a hydatid cyst has been described as a hypo­dense, nonenhancing, oval homogenous mass with a hyperdense rim ( 1- 3.4,6- 10). Our case, in addition, showed bowing of the medial orbital wall without bony erosion and evidence of a septum running through the cyst. Other cystic lesions of the orbit occurring in childhood such as dermoid cyst, encephalocele, sinus mucocele, and teratoma do not display septations and bone displacement. Thus it is important to know the presence of these features in the differential diagnosis of unilateral exophthalmos in patients from countries where echinococcosis is endemic. The only current definitive treatment is total sur­gical excision of the cysts when possible ( 1- 13). At the surgery, aspiration or opening of the cyst should be avoided unless removal cannot other­wise be accomplished ( 11). When the cyst wall was torn, the beneficial effect of irrigation with hyper­tonic saline solution as an adjunct to the surgical treatment is reported ( 4,13). In our case, the area of spillage was irrigated with this solution, but the recurrence of the disease developed in the same area. Pearl et a1. reported that mebendazole was FIG. 4. Three years later. repeat axial ( A) and coronal ( 8) scans demonstrating almost complete resolution and resultant calcified residue ( arrows). I elin Neuro- ophthalmol, Vol. 12, No. 1, 1992 46 M. TURGUT ET AL. exceedingly active against Echinococclis grt1llll/ 0SlIS cyst ( 12). In the present case, treatment with an antihelminthic drug was started and caused com­plete clinical and radiological response with a small calcified residue. As occurs with cerebral cys­ticercosis and tuberculosis ( 14,15), echinococcosis may eventually calcify and regress into scars after medical treatment ( 4,16). To our knowledge, the present case is the first report of a calcified residue seen in a patient with orbital hydatid cyst follow­ing treatment. Acknowledgment: The authors thank Dr. N. S. Oz­tekin, who reviewed neuro- ophthalmological details; Dr. M. Gran, who assisted with radiographic interpre­tations; and Dr. F. Turgut, who collected the necessary data for this work. REFERENCES 1. Martz RD, HoH IT. Parasitic and fungal diseases of the central nervous svstem. In: Youmans JR, ed. N" l/ fl, lo'<:/ CI/ t Sl/ rgery. Vol. 6. Philadelphia: WB Saunders, 1990: 3742:"' 51. 2. 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