Segmental acne versus mosaic conditions with acne lesions.

Acne rarely presents in segmental patterns, which are encountered only in cutaneous mosaicism. We report herein two cases of segmentally arranged acne and systematically review the literature on the topic. Beside already known mosaic conditions which may show primary lesions typical of acne, i.e. nevus comedonicus, Happle-Tinschert syndrome, acne superimposed on epidermal nevi and mosaic Apert syndrome, we introduce the possibility that acne itself may present in a mosaic form. As from the extremely small casuistics retrieved, segmental acne is not present at birth, follows Blaschko lines, is polymorphous in nature and occurs on locations typical of common acne.