Cystic degeneration of pleomorphic adenoma of the lacrimal gland: a diagnostic dilemma.

Pleomorphic adenoma of the lacrimal gland is a benign epithelial neoplasm and can rarely undergo cystic degeneration, mimicking other conditions with similar radiological findings. It commonly presents as a slow growing, painless mass in the outer upper eyelid, characterised by exophthalmos, ptosis, diplopia and reduced ocular movements. Here, we present one such case of a male in his mid-30s presenting with a painless, progressive fullness in the left upper eyelid with mild proptosis and restricted ocular movements which was initially suspected to be due to an underlying dermoid cyst owing to the cystic nature of the lesion on imaging. Surgical intervention involving complete excision was preferred, rendering no recurrence on follow-up. Histopathological examination however revealed microscopic features suggestive of a pleomorphic adenoma with cystic changes contrary to the initial diagnosis of a dermoid cyst. This case highlights the challenges faced in arriving at the right diagnosis with successful treatment outcomes.