A 6-year-old boy is referred to dermatology for evaluation of his dry, thin skin. Since birth, it has frequently torn, and it burns with the application of almost any product or soap. Neither OTC nor prescription products have helped.
The boy is reportedly in good health otherwise and is not atopic. Nonetheless, two of his siblings are similarly affected, and there is a strong family history of similar dermatologic problems on his father’s side. He and his family are from Mexico and have type IV skin.
The patient is in no distress but does complain about his skin problems. His skin is quite thin and dry, and fine scaling covers his palms, face, legs, trunk, and scalp. In short, none of his skin looks normal. The skin on his legs is especially scaly and has a pronounced reticulated appearance.
His fingernails are dystrophic, with transverse ridging and a loss of connection between the cuticles and nail plates.
What is the diagnosis?