Abstract
Anti-N-methyl-D-aspartate receptor (NMDAr) encephalitis is an autoimmune encephalitis that commonly presents with various neurobehavioral symptoms. Anti-NMDAr encephalitis is known to occur more commonly in young females with teratoma. In this case, we report a rare presentation of hypersexual behavior in a 21-year-old African-American male, with an incidental finding of multicystic scrotal mass, who was also diagnosed with anti-NMDAr encephalitis. The patient had no significant past psychiatric or medical history and presented for psychiatric hospitalization with severe hypersexual behavior, aggression, disorganized thoughts, and fluctuating confusion as characterized by forgetfulness, disorientation, and distractibility, with poor response to various psychiatric medications. His laboratory tests and imaging studies were unremarkable. Cerebrospinal fluid analysis showed anti-NMDAr antibodies. Prompt treatment with intravenous immunoglobulin and methylprednisolone significantly improved the symptoms. This case illustrates that clinicians should be aware that nonspecific symptom such as hypersexual behavior may also be a predominant presenting symptom in anti-NMDAr encephalitis.