Progressive macular hypomelanosis: a rarely diagnosed hypopigmentation in Caucasians

Abstract

A 35-year-old woman who developed whitish macules on trunk and limbs at 12 years of age and observed a remarkable increase of the hypopigmentated lesions after her pregnancies at ages 29 and 32 years. Because of the highly characteristic clinical aspect and the light- and electron-microscopic histopathologic findings, we diagnosed progressive macular hypomelanosis (PMH). It is a nonscaly disorder with hypopigmented macules mainly on the trunk and is more often seen in young women. In contrast to some authors assuming the presence of Propionibacterium spp. as a matter of principle in PMH, we report a case with no evidence for Propionibacterium spp.

Figure 1

(a) Disseminated whitish macules on the front and the back of the trunk. (b) Nonscaly macules in detail on the back.

Figure 2

Electron microscopy of non-affected skin. Left (8:300×): numerous melanosomes aggregated in big clusters and disseminated melanosomes. Right detail (49:800×): Granular melanosomes mostly grade III-IV.

Figure 3

Electron microscopy of affected skin. Left (8:300×): sparse melanosomes aggregated in small clusters and some solitary. Right detail (49:800×): Melanosomes mostly grade I-II, few grade III and less granular.