Smith and Sandra C. have specific serum autoantibodies and corresponding neurologic syndromes, connected neoplasms, and, in some cases, responsiveness to immunotherapies. Taken collectively, these features constitute recognizable syndromes.1,2 Autoantibodies to Ma2, also known as anti-Ta, are a known marker for paraneoplastic brain-stem or limbic encephalitis associated with germ-cell tumors of the testis.3C5 Patients have been described who have seminoma-associated paraneoplastic encephalitis but do not have IgG autoantibodies to Ma2 or to some other antigen and don’t have specific immunofluorescence staining patterns on central nervous system tissue from mice.6C8 We describe a 37-year-old man (Patient 11) who underwent surgery to remove a testicular seminoma and received chemotherapy 3 years before the onset of progressive brain-stem and cerebellar encephalitis, or rhombencephalitis. Standard paraneoplastic autoantibodies, including Ma2 IgG, were not detected. Using a customized phage display system,9 we recognized antibodies to the human being protein kelch-like protein 11 (KLHL11) with this individuals cerebrospinal fluid. KLHL11 is definitely a member of the E3 ubiquitin-protein ligase complex involved in protein ubiquitination.10 The same antibody was recognized in 12 other patients. CASE Statement A remaining testicular seminoma (tumorCnodeCmetastasis stage T2N0M0) was diagnosed in the patient at 32 years of age; he was treated with orchiectomy and a single cycle of carboplatin, and he was in remission for 45 weeks. Over a 9-month period, vertigo and truncal and appendicular ataxia Cytochalasin B developed; these conditions were complicated by diplopia 5 weeks before presentation. Exam 54 weeks after orchiectomy showed horizontal and vertical nystagmus having a rotatory component, intention tremor of the right arm with dysdiadochokinesia, dysmetria Cytochalasin B on fingerCnoseCfinger screening on the right part, and a wide-based, cautious gait with impaired tandem gait. Magnetic resonance imaging (MRI) of the brain showed a nonenhancing hyperintense area adjacent to parts of the fourth ventricle on T2-weighted images (Fig. S1A in the Supplementary Appendix, available with the full text of this article at NEJM.org). The cerebrospinal fluid contained 32 leukocytes per Cytochalasin B cubic millimeter, having a red-cell count of 11 per cubic millimeter, a protein concentration of 59 mg per deciliter, and a glucose concentration of 56 mg per deciliter (3.1 mmol per liter). The individuals neurologic symptoms worsened, and he received intravenous methylprednisolone at a dose of 1 1 g daily for 5 days, followed by tapering doses of oral prednisone. Three weeks later on, the truncal ataxia experienced improved and the eye-movement abnormalities, intention tremor, and dysmetria experienced resolved. He consequently received intravenous immune globulin at a dose of 0. 4 g per kilogram of body weight daily for 5 days and then regular monthly for 3 months. He received glatiramer acetate for any presumptive analysis of multiple sclerosis and experienced increasing ataxia over the next 8 weeks. An MRI showed an enlarged and hyperintense remaining substandard olive on T2-weighted images that did not enhance with the administration of gadolinium and was tentatively interpreted like a brainstem glioma (Fig. S1B in the Supplementary Appendix). The cerebrospinal fluid at that time contained 0 Rabbit Polyclonal to MARK leukocytes per cubic millimeter, a red-cell count of 1 1 per cubic millimeter, protein concentration of 35 mg per deciliter, glucose concentration of 64 mg per deciliter (3.6 mmol per liter), and 14 oligoclonal bands that were not present in the serum (normal array, 2 oligoclonal bands). The reinitiation of high-dose glucocorticoid therapy led to resolution of the positional vertigo, and he received maintenance therapy with regular monthly intravenous immune globulin and rituximab. At his initial evaluation, the patient was enrolled in a research study for detection of pathogens and autoantibodies. This study included antigen finding by programmable phage display.9 After identification of a candidate autoantigen, samples of the patients serum and cerebrospinal fluid were evaluated to characterize the immunofluorescence staining pattern. The immunofluorescence signal was sparse and punctate.