Role of ultrasound and CT-scan in diagnosis of hydatid cyst of the orbit.

Hydatid cyst of the orbit is a rare cause of proptosis, even in endemic countries like India. We report two histopathologically proven cases with ultrasonographic and computerized tomographic correlations. Both patients had marked dimness of vision and disc edema. One of them did not regain vision following cyst removal because of optic atrophy. The two cases indicate that hydatid cyst should be retained as a differential diagnosis of unilateral proptosis with disc edema. A combined ultrasound and CT-scan should be done to establish the diagnosis. An attempt should also be made at complete surgical removal of the cyst.