Leptomeningeal metastasis from occult signet-ring cell colon adenocarcinoma presenting with isolated headache.

We report a patient with a rare primary signet-ring cell carcinoma of the transverse colon with secondary leptomeningeal carcinomatosis. The only presenting and persistent symptom was worsening headache for 6 weeks until death. There were no other neurological, constitutional, or gastrointestinal symptoms. The primary tumor was detected by CT scan and confirmed by endoscopy, and the final diagnosis was eventually made from cerebrospinal fluid and tissue cytology. This report confirms the dismal prognosis of leptomeningeal carcinomatosis, especially when the primary malignancy is asymptomatic.