Multiple Cranial Neuropathies as the Initial Presentation of Primary Ductal Adenocarcinoma of the Lacrimal Gland.

Primary ductal adenocarcinoma of the lacrimal gland is a rare, aggressive malignancy that clinically and histologically resembles salivary duct carcinoma. Similar to other malignant epithelial lacrimal gland tumors, ductal adenocarcinoma typically presents with unilateral proptosis, pain, upper eyelid swelling, palpable mass, diplopia, ptosis, and blurred or decreased vision. Rarely, primary malignant epithelial lacrimal gland tumors may first present with multiple cranial neuropathies due to occult spread to the cavernous sinus, as in this case. With such a vast differential diagnosis, a practical yet systematic approach to multiple cranial neuropathies, as guided by clinical history, exam, and neuroimaging, allows for a more targeted diagnostic evaluation, especially when multiple diagnostic tests and interventions return unrevealing. A repeat biopsy or complete excision of the lacrimal gland may be necessary to yield the correct diagnosis.