Derm Dx: Extensive blistering on the elbows, knees, forearms, and feet

A patient aged 3 years presents with skin fragility and sporadic blistering that her parents first noticed during infancy. The condition worsened when the patient began to crawl, and she developed extensive blistering on her elbows, knees, forearms, and feet.

The patient now appears to develop a blister anytime there is friction or trauma to the skin.