A case of actinic granuloma associated with periumbilical perforating pseudoxanthoma elasticum.

We report an unusual case of actinic granuloma of the face and periumbilical perforating pseudoxanthoma elasticum located superior to the umbilicus in a 57-year-old Korean woman. Histopathologically, these two dermatoses have a similar degeneration of elastic fibers, but they show different host reactions to the altered elastic fibers. In the actinic granuloma, actinically damaged elastic fibers were followed by granulomatous infiltration on the sun-exposed area, while in the perforating pseudoxanthoma elasticum, the altered elastic fibers induced a foreign body reaction, with subsequent transepidermal elimination. This is the first case report showing both actinic granuloma and periumbilical perforating pseudoxanthoma elasticum in the same patient, which suggests that the basic mechanism eliciting these dermatoses is similar.