Single and multiple keratoacanthomas after a recent black tattoo in two patients

As studies on keratoacanthomas (KAs) within tattoos are scarce, our comprehension on the development of KAs in tattoos remains limited. Notably, existing studies predominantly focus on KAs found in tattoos containing red ink. This study addresses these gaps by documenting two cases of KAs within recently applied black and grey tattoos. The first case, a woman in her mid-40s, presented with two painful hyperkeratotic lesions in the tattooed skin on her left forearm and, notably, one similar simultaneously grown asymptomatic papule outside the tattooed skin. The second case, a man in his early 40s, presented with a painful hyperkeratotic nodule on a tattoo on the right leg. Histopathology showed that the nodules in both patients were compatible with a KA. After discussing therapeutic options, both patients opted for a wait-and-see approach, whereafter, the nodules regressed within months.