CNS listeriosis confused with leptomeningeal carcinomatosis in a patient with a malignant insulinoma.

We describe a case of presumed listeria monocytogenes rhomboencephalitis, which was initially confused with leptomeningeal carcinomatosis in a patient with a malignant carcinoid tumor. Long-term corticosteroid treatment and immunosuppression caused by malignancy predisposed the patient to developing listeriosis. The clinical and radiologic features of this illustrative case are described. Listeriosis is an important treatable differential diagnosis in patients with malignancy presenting with neurologic signs.