A tattoo is the result of the deposition of exogenous pigment into the skin. This may be purposeful or accidental. Accidental tattoos may occur after abrasion injuries introducing asphalt, graphite, or carbon into the injured skin. Rarely, medically induced tattoos have developed after the use of ferrous subsulfate solution (Monsel’s solution) for coagulation purposes. While traumatic tattoos are not rare, decorative tattoos are more common.
Tattooing has been practiced for thousands of years for purposes of identification, group affiliation and protection, and artistic expression.
In the modern world, tattooing is often done by tattoo artists using electric needles to introduce particles of pigment into the dermis. Other tattooists may use any pointed object to place pigment particles into the various layers of the dermis or epidermis. Tattooing remains a common custom in many countries and cultures. It gained popularity in Western countries throughout the 1990s. In the past, decorative tattoos were primarily seen in men, especially in groups such as sailors and members of the armed forces; however, in North American culture today, they are increasingly observed in young professionals of both sexes. The components of many tattoo pigments have been identified, although new formulations continue to appear (see Tattoo Pigments, below).
Complications resulting from decorative tattoos are surprisingly rare, but the incidence is increasing.
The introduction of foreign substances into the skin can result in a number of adverse effects, including toxic or immunologic reactions to the tattoo pigments, transmission of infectious diseases, and the localization of skin disease within the tattoo. An immunologic reaction to a tattoo may be an acute inflammatory reaction or an allergic hypersensitivity. The histopathologic pattern can be granulomatous, lichenoid, or pseudolymphomatous.
See the image below.
Types of reactions include but are not limited to acute inflammatory reactions, granulomatous reactions, lichenoid reactions, sarcoid reactions, photo-aggravated reactions, and MRI sensitivity reactions. Images courtesy of Science Photo Library (top left), NIH (top and bottom right; center), and Medscape Drugs & Diseases (bottom left).
Motivation for the removal of tattoos varies among individuals. The reasons can range from feelings of regret to the development of an adverse reaction in the skin. Many tattoo removal methods exist. Also see Tattoo Lasers.