A case of treatable dementia with Lewy bodies remarkably improved by immunotherapy.

We report a case of probable dementia with Lewy bodies (DLB) with several findings indicating autoimmune encephalitis (e.g. anti-thyroid antibodies in serum and oligoclonal band and anti-N-methyl-d-aspartic acid receptor antibodies in cerebrospinal fluid). The symptoms and the findings of ancillary tests such as Iodine-123-metaiodobenzylguanidine myocardial scintigraphy and 99m Technetium-ethyl-cysteinate-dimer single photon emission computed tomography were improved after the pulse and oral steroid treatment. This case is thought the autoimmune encephalitis mimicking DLB. This experience indicated the importance of suspecting treatable DLB even when the findings of laboratory and radiological tests fulfill the diagnostic criteria of DLB.