Linear porokeratosis associated with disseminated superficial actinic porokeratosis: a new example of type II segmental involvement.

The coexistence of linear porokeratosis (LP) and disseminated superficial actinic porokeratosis (DSAP) in a 3-year-old girl with a family history of DSAP is presented. Happle proposed loss of heterozygosity (LOH) to explain the origin of this unusual phenomenon. Homozygosity would explain why lesions in LP are far more pronounced than those of the associated heterozygous DSAP lesions.