Multiple Myeloma Presented With Testicular Involvement at Initial Diagnosis on 18 F-FDG PET/CT.

Extramedullary involvement is a rare presentation of multiple myeloma (MM), and testicular involvement is even rarer. Testicular involvement associated with poor prognosis and orchiectomy is necessary for definitive diagnosis. Although 18 F-FDG PET/CT is well-known for its ability to detect extramedullary involvement and assess treatment response in MM, testicular involvement of MM on 18 F-FDG PET/CT at initial diagnosis has not yet been reported. Herein, we present a rare case of MM with testicular involvement at initial diagnosis.