Intraorbital and intracranial extension of adenoid cystic carcinoma without clinical or radiological lacrimal gland involvement.

Adenoid cystic carcinoma (AdCC) is a rare epithelial neoplasm of the head and neck, most commonly found in the salivary glands. Orbital AdCC is an uncommon clinical entity arising from the lacrimal glands, however primary orbital AdCC has been previously described in a small number of case reports. The exact origin of the neoplasm with uninvolved lacrimal gland in the orbit is unknown, however it may arise from ectopic lacrimal or salivary gland tissue, or extension from nearby epithelial structures. We describe the clinical characteristics, investigations and management of a 55-year-old man presenting with vertical diplopia, found to have left posterior orbital AdCC invading the skull base with intracranial extension involving the inferotemporal fossa, pterygopalatine fossa, left carotid artery, cavernous sinus and temporal lobe dura, without clinical or radiological lacrimal gland involvement or systemic metastases.