[Progressive macular hypomelanosis successfully treated with topical clindamycin and benzoyl peroxide].

Progressive macular hypomelanosis is an acquired skin pigmentation disorder that was initially thought to be related to racial characteristics, but is currently more often associated with the presence of Propionibacterium acnes. A 23-year-old woman was seen for the progressive appearance over a 5-year period of asymptomatic whitish lesions on the trunk (Figures 1A and 2). The lesions were poorly defined, nondesquamating, hypopigmented macules tending to become confluent. The macules were initially located in the center of the chest but had spread centrifugally to affect the neck and the most proximal regions of the upper limbs. The lesions did not improve in summer, but rather tended to stand out more noticeably against the adjacent skin. The patient had no history of atopic dermatitis or other eczematous disorders, and had never reported pruritus or desquamation of the lesions. After other causes of acquired hypopigmentation, such as resolving pityriasis alba or pityriasis versicolor, had been ruled out clinically, the patient was diagnosed with have found a statistically significant prevalence of diabetes mellitus6; and f) repeated trauma (Koebner phenomenon).3 The isomorphic response, also known as the Koebner phenomenon, consists of the appearance of typical lesions of a certain dermatosis in areas of healthy skin that have previously been subjected to different kinds of trauma. They are divided into 4 groups: