Limbic encephalopathy as a nonmetastatic complication of oat cell lung cancer. Its reversal after treatment of the primary lung lesion.

A 52-year-old white woman presented with dementia, a seizure disorder, and an inappropriate affect characteristic of limbic encephalopathy. Chest x-ray showed a mass lesion that, on biopsy, proved to be oat cell carcinoma. Her central nervous system symptoms improved following radiotherapy limited to the primary lesion and later resolved completely with attainment of a complete remission after chemotherapy with cyclophosphamide, doxorubicin, vincristine, and VP-16--drugs unable to penetrate the cerebrospinal fluid. The resolution of the paraneoplastic syndrome in this patient without the addition of cranial irradiation suggests that a trial of cytoreductive therapy is warranted in patients with limbic encephalopathy associated with an underlying neoplasm.