An 85-year-old woman presented with decreased visual acuity. MRI of the brain revealed bilateral orbital masses, and FDG-PET/CT demonstrated moderate to intense uptake in the orbital tumors and thickened skin on the left lower leg. Biopsies of the orbital and cutaneous lesions revealed infiltration by T-cell lymphoma, and the presence of human T-cell lymphotropic virus type 1 antigens confirmed the diagnosis of adult T-cell leukemia/lymphoma (ATLL). Although orbital ATLL is rare, the skin is a common site of extranodal involvement of T-cell lymphomas, including ATLL, and FDG uptake by a cutaneous lesion can facilitate early diagnosis.