Abstract: Bullous mastocytosis (diffuse cutaneous mastocytosis) is a rare form of mast cell disease that begins during the first month of life and causes extensive blisters that mimic scalded skin syndrome or bullous erythema multiforme. Discrete pigmented macules, papules, and nodules arc absent and the characteristic leathery induration of skin may not develop until 6 months of age. Skin biopsy shows a subepidermal blister with mast cells at the base. The most serious complications are gastrointestinal hemorrhage and shock. The symptoms of bullous mastocytosis may be modified by a number of new therapeutic agents.