Episodic Unilateral Mydriasis - Malignancy Or Lyme Induced?

A 20-year-old Caucasian male with known history of signet ring cell colorectal cancer status-post resection and chemotherapy four years prior presented to OSH with one month history of headache, fever, nuchal rigidity, photophobia and horizontal diplopia concerning for aseptic meningitis with bilateral 6th nerve palsy. Serum and CSF evaluation was negative except for positive Lyme antibodies. Brain MRI showed mild meningeal enhancement. He was treated for Lyme meningitis with IV antibiotics but showed no improvement after two weeks. After transfer to our center for further management, patient had an event in which right pupil measured 5mm diameter reactive to neither light nor accommodation, left pupil measured 4mm with brisk reaction to light and accommodation. There was no afferent pupillary defect by reverse testing. Re-examination performed within 10 minute of the initial examination showed briskly reactive bilateral pupils to light and accommodation with neither efferent nor afferent defects. On the following day, again the same episodic of right pupillary involvement was observed. Repeat work up with MRI Brain/Spine revealed multiple enhancing lesions, lumbar puncture showed an opening pressure > 55 cmH20, atypical tumor cells positive for AE1/AE3 and CK20 (consistent with colorectal adenocarcinoma), and elevated carcinoembryonic antigen level concerning for leptomeningeal carcinomatosis. Intraventricular chemotherapy with methotrexate and gemcitabine through an Ommaya reservoir was initiated with subsequent improvement of symptoms.