An 84-year-old man with a history of diffuse large B-cell lymphoma in remission who had completed chemotherapy 3 years previously was referred for imaging evaluation of disease recurrence. Abnormal accumulation in the left scrotum was demonstrated on 18F-FDG PET/CT. Subsequent ultrasonography showed a nodular mass lesion in the left epididymis. He then underwent left orchiectomy. Histopathological examination of the mass diagnosed smooth muscle hyperplasia/hamartoma of the left epididymis. Epididymal smooth muscle hyperplasia/hamartoma should be included as a differential diagnosis for malignant scrotal tumor.