Progressive and extensive hypomelanosis and extensive pityriasis alba: same disease, different names?

We report the cases of five female patients with high skin phototype affected by relapsing, hypochromic, non-scaling macules occurring after the summer on the back and spreading over large areas of skin. Histological features disclosed decreased epidermal melanin. Psoralen plus ultraviolet A (PUVA) treatment proved to be beneficial, but new relapses were noted after stopping treatment. Clinical and histological features were consistent with the diagnosis of 'progressive and extensive hypomelanosis' described by Guillet in persons of mixed racial background. We discuss the differential diagnosis of the latter entity with respect to the other idiopathic acquired primitive hypomelanosis and hypothesize an overlapping with the so-called extensive pityriasis alba (EPA).