Idiopathic Guttate Hypomelanosis Treated with 308-nm Excimer Light and Topical Bimatoprost

Idiopathic guttate hypomelanosis (IGH) is an acquired pigmentary disorder that is characterized by the presence of multiple hypopigmented macules on the shins and forearms. Albeit asymptomatic, it can cause considerable cosmetic anxiety. The pathogenesis is not fully understood and to date, there have been no successful treatments. We report a case of a 48-year-old female who presented with an 8-year history of multiple hypopigmented macules on both legs, typical of IGH. She previously failed to respond to topical pimecrolimus. She received targeted phototherapy with an excimer lamp (308 nm, 250-480 mJ), and a small patch was treated once daily with topical bimatoprost, in addition to the excimer lamp. After five sessions, better improvement was noted on the combination treatment patch; she received combination treatments for further six sessions. Good repigmentation has been achieved on the smaller macules. The larger depigmented macules continue to improve with further treatments. A combination of excimer light with topical bimatoprost appears to be a promising potential treatment option for IGH, a condition where management options are otherwise limited.