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BACKGROUND:Neuroendocrine tumors represent an expansive group of neoplasms that share an etiology of epithelial origin with neuroendocrine differentiation. Poorly-differentiated neuroendocrine carcinomas behave similarly to their aggressive pulmonary counterpart, small cell lung carcinoma. Most patients with gastroenteropancreatic neuroendocrine tumors present with symptoms of metastasis, most commonly to the liver. There have been no case reports, to our knowledge, until now that demonstrate metastasis to the central nervous system. CASE PRESENTATION/METHODS:A 72-year-old male with poorly-differentiated stage IIIB neuroendocrine carcinoma of the colon presented with acute altered mental status and right facial droop. Head CT was negative for an acute hemorrhagic process without evidence of suspicious lesions. Several days later, the patient developed fever and neck stiffness suspicious for bacterial meningitis. A lumbar puncture procedure was performed. Cytology of the CSF demonstrated metastatic disease to the central nervous system and the final diagnosis of carcinomatous meningitis secondary to metastatic neuroendocrine carcinoma of the colon was made. CONCLUSIONS:High-grade gastroenteropancreatic neuroendocrine carcinomas most commonly metastasize to the liver, which often corresponds with the patient's initial presentation. When neuroendocrine tumors do metastasize to the central nervous system, the primaries are most commonly of pulmonary origin. When meningeal metastasis does occur, it commonly presents as neurologic deficits or cerebrovascular events, rarely does meningeal metastasis mimic bacterial meningitis with symptoms of fever, photophobia and meningismus. As neuroendocrine carcinomas have been increasing in incidence over the past several decades, it is important to consider varying metastatic presentations when working up a patient with a diagnosis of neuroendocrine tumor.