[Keratoacanthomas on recent tattoos: Two cases]

Increasing numbers of reports of rapidly arising, isolated or eruptive keratoacanthomas (KA) and squamous cell carcinomas (CSC) on the red part of tattoos tend to suggest a non-fortuitous link with the procedure. We report herein two different presentations of KAs on tattoos: one patient with multiple eruptive KAs on sun-exposed areas of a recent red tattoo and another with a solitary lesion on a recent tattoo. We discuss the issues related to the distinction between KAs and CSCs in this particular context.

Case No. 1: A 55-year-old heavily tattooed man presented multiple round keratotic verrucous-like lesions restricted to a red tattoo. The tattoo had been performed by a professional tattooist in summer 2016, a week before the onset of the symptoms. The patient did not protect a part of his tattoo from sun-exposure during the healing phase and lesions developed only on the sun-exposed tattooed parts. In January 2017, he consulted with about ten lesions. The histologic study by shaving of a lesion militated in favor of a CSC, KA type. The physical examination was unremarkable. He had no previous history of skin cancer. Two weeks later, most of the lesions regressed spontaneously. Based on the clinical history and progression of the lesions, a diagnosis was made of eruptive KA on a red tattoo. Residual lesions were treated by cryotherapy or excision. Case No. 2: A 72-year-old woman developed a 1-cm painful dome-shaped nodule with a central crust three weeks after tattooing. Full excision confirmed the diagnosis of KA.

To date, we have found 31 case reports and series (17 men, median age: 50.5 years) of KA and CSC on tattoos. Lesions usually develop rapidly after completion of the tattoo, after between one week and several months. Exceptional cases have been described in old tattoos. Red tattoo ink is most commonly the culprit. The main difficulty lies in distinguishing between KA and CSC. Nowadays pathologists agree that a KA should be considered as a variant of CSC. Eruptive forms of KA present a peculiar situation. They may sometimes be inherited, and KA on recent traumatized areas or drug-induced have been described. Like other authors, we believe that cases of CSC on red tattoos belong rather to the KA type. The physiopathogenesis of tattoo-associated eruptive KA and CSC is not clearly understood, but could be multifactorial, involving: the trauma induced by tattooing, local inflammatory reaction, a component of the red ink, external factors such UV exposure, and a possible genetic predisposition. Rapidly arising KA and eruptive KA on top of recent (red) tattoos are not fortuitous. The lesions should be excised and the patient monitored. Additional studies on tumor specimens are warranted to identify the possible causative agents in tattoo ink that may be responsible for such reactions.