Background: Hydatid disease is one of the common zoonotic diseases caused by the larval stage of Echinococcus granulosus. It is endemic in sheep-raising and cattle-raising areas worldwide and humans are an accidental intermediate host following the ingestion of the larvae. Head and neck involvement of echinococcosis is a rare entity and involvement of the infratemporal region is extremely rare even in endemic areas. Only a few cases of hydatid cysts located in the infratemporal fossa have been reported in the literature. Moreover, extension of the hydatid cyst into the intraorbital region and infiltrating into the surrounding orbital bone is even rarer.
Case presentation: We present a case of a 65-year-old Gurung Nepalese woman with painless proptosis of her left eyeball of 2 months' duration with recent progressive diminution of vision for 15 days. Radiological findings showed a cystic mass in the left infratemporal fossa extending into the left orbit and involving the surrounding orbital bone. Surgical removal was carried out. On histopathological evaluation, it was reported as hydatid cyst infiltrating into the bone. She was prescribed albendazole and discharged after surgery. However, she was lost to follow up and returned after 15 months with recurrence and proptosis of the same eye. Repeat excision of the lesion was carried out and postoperatively she was administered tablet albendazole. She was found to be disease free after 6 months of follow up.
Conclusions: Clinical and radiological findings are important but may not be sufficient in the preoperative diagnosis of hydatid disease especially if rare sites are involved. Proptosis may be seen in several conditions and orbital or infratemporal hydatidosis, although rare, should be considered a differential diagnosis.
Keywords: Echinococcus; Hydatid cyst; Infratemporal fossa; Orbit; Proptosis.