Unknown: Papules on the knees. Elastosis perforans serpiginosa (EPS).

Elastosis perforans serpiginosa (EPS) can occur in patients with an underlying connective tissue disorder. Down syndrome, osteogenesis imperfecta, acrogeria, Ehlers-Danlos syndrome type IV, Marfan syndrome, pseudoxanthoma elasticum, Rothmund-Thomson syndrome, and scleroderma have all been associated with EPS. The clinical appearance exhibits umbilicated papules arranged in a typical serpiginous pattern, usually located around the neck. Less frequently, lesions may be seen on the face, abdomen, and extremities with a symmetrical distribution, as in our case. The clinical course may be variable with a spontaneous resolution in a few months or years, but frequently new lesions develop leading to persistence and progression of the disorder. We describe a 12-year-old girl affected by Down syndrome who presented a localized form of EPS, which involved only the extremities. Strangely, it resolved spontaneously after biopsy with no recurrence, without therapy.