A 70-year-old man presented with 2 years history of a painless hard mass in the left scrotum. Both pelvic computed tomography and magnetic resonance image showed enhancement only in the wall of the tumor, indicating a benign disease, rather than a neoplastic lesion. Physical examination 3 weeks after the first presentation showed the remarkable reduction of the left testicular size. Left inguinal orchiectomy was carried out and pathological diagnosis was seminoma with extensive necrotic areas occupying mostly the tumor. Either shrinkage or enlargement of testicular size with a long history demands full investigation for malignancy.