Cystic Intracranial Recurrence of Olfactory Neuroblastoma without Accumulation on Fluorine-18-fluorodeoxyglucose Positron Emission Tomography

A 66-year-old man underwent multimodal treatment for olfactory neuroblastoma (ONB). When he was 72 years old, a cystic intracranial lesion without accumulation on fluorine-18-fluorodeoxyglucose positron emission tomography was detected. Surgical resection was performed when the patient was 73 years old. The pathological examination revealed recurrence of ONB, and the patient underwent focal irradiation. At age 81, he presented with a second recurrence in the right occipital lobe with radiological and pathological findings similar to the prior recurrence. This case suggests that pathological confirmation should be considered in cases with atypical radiological findings following the treatment of ONB.