An 11-year-old Italian boy with type 1 diabetes mellitus with onset in 2004 was brought to the Department of Pediatrics for a routine visit during which a large hemangioma in the left leg was observed (Figure, A). The hemangioma had been present since birth, had a distinct linear border along the midline of the leg, and extended from the lumbar region to the foot (Figure, B and C). The boy did not report any pain or itching. At clinical examination, compared with the right leg, the left leg was 1.5 cm longer, its circumference was 2 cm wider, and it was warmer. Its aspect was characterized by a large superficial venous reticulum. Color Doppler ultrasonographic examination of the affected leg revealed only mild femoral vein incontinence. Results of magnetic resonance imaging of the brain were negative for arteriovenous malformations and hemangiomas.