Didymosis aplasticosebacea Q84.8

Didymosis aplasticosebacea denotes the very rare concordant coincidence of aplasia cutis circumscripta with a nevus sebaceus.
Happle compiled 15 cases from the literature in 2001. The total published number of this syndrome is probably < 20 cases.

Didymosis, a special form of a cutaneous mosaic, is defined as twin spots (or didymosis; from didymos = twin), which are defined as the paired occurrence of mutated areas. These differ both from each other and from the surrounding heterozygous tissue.

1. Demerdjieva Z et al (2007) Epidermal nevus syndrome and didymosis aplasticosebacea. Pediatric dermatol 24:514-516.
2. Happle R et al (2001) Didymosis aplasticosebacea: coexistence of aplasia cutis congenita and nevus sebaceus may be explained as a twin spot phenomenon. Dermatology 202:246-248.