A case is presented of a patient with a history of low-intensity smoking, with an accumulated tobacco index of less than 5 packs-year and without other personal history of interest. She went to the emergency room several times over 2 months, complaining of a diffuse, oppressive and intermittent headache and diplopia accompanied by occasional blurred vision, being diagnosed with ischemic paralysis of the fourth cranial nerve of the left eye and initiating treatment with antiplatelets. Despite treatment, she returned to the emergency room within a week, as she had been suffering from progressive dizziness, instability when walking, loss of vision mainly in the left eye and a greater feeling of weakness in the upper limbs. Finally, admission to Neurology was decided upon with the suspicion of subacute tuberculous meningoencephalitis. However, after various diagnostic tests, it was concluded that it was a pulmonary adenocarcinoma, which began as meningeal carcinomatosis without presenting associated respiratory symptoms.