Phacomatosis melanovascularis: a new example of non-allelic twin spotting.

We report an infant who had a combination of two rather common nevoid skin conditions, namely "telangiectatic nevus" or "capillary malformation", and "hyperpigmented mosaicism" or "segmental pigmentary disorder" in close apposition, occupying large areas of the body in a mosaic distribution. This association may be considered a further example of didymosis, for which we propose the term, "phacomatosis melanovascularis" to denote a possible non-allelic twin spotting condition. To our knowledge, this is the first case reported in the literature.