Tattooing: medical uses and problems.

Decorative tattooing is a custom thousands of years old and is growing in popularity today. Medical professionals may be less familiar with its medical applications-medical alert tattooing, reconstructive and cosmetic applications, endoscopic tattooing, corneal tattooing, tattooing in radiation oncology, and uses in forensic medicine. We review current medically related tattooing applications and discuss their potential risks and benefits.