[Pilomatrixoma in a tattoo].

A 31-year-old man developed a fast-growing tumor on the right upper arm within a black tattoo, which could be classified histologically as pilomatrixoma. While the age of the patient and the rapid growth of the tumor cannot be regarded as typical findings of pilomatrixomas, the localization on the upper arm is one of their predilection points. Despite the wide spread use of tattoos in the last few decades, tumor development in tattooed skin is rarely reported. It is still controversial whether the ingredients of the tattoo agents can be responsible for tumor induction.