A woman in her 50s presented with diffuse blue to slate-gray patches on her entire face immediately after administration of Q-switched Nd:YAG laser toning (Figure 1A). These pigmented lesions corresponded exactly to areas that had previously received laser treatment. Her history was remarkable for rheumatoid arthritis treated with oral gold salts 15 years ago, but the total dosage of gold salts could not be determined. Rechallenge with the original Q-switched Nd:YAG laser was administered on the right forearm, and a similar slate-gray macule developed immediately (Figure 1B). A skin biopsy specimen of the lesion on the right side of the woman’s face was obtained, and histopathologic evaluation was conducted.
Chu C, Chou C, Cheng Y. Immediate Pigmentation After Laser Treatment. JAMA Dermatol. 2015;151(9):1021-1022. doi:10.1001/jamadermatol.2015.1569