It is believed that viral infections and the hyperimmune reaction due to these infections are involved in the etiology of Kikuchi-Fujimoto Disease (KFD), a rare cause of fever of unknown origin. Axillary lymphadenopathy and neurologic involvement are rare in KFD. We present a patient diagnosed with KFD histopathologically during an investigation of the origin of fever and axillary lymphadenopathy. Subsequently, incidental sinus aspergilloma was diagnosed radiologically in the patient and acute disseminated encephalitis developed during follow-up. This report aims to draw attention to the co-existence of KFD and Acute Disseminated Encephalomyelitis, two diseases of which the origins are not clear.