Three cases of diffuse cutaneous mastocytosis (DCM) were at first incorrectly diagnosed as staphylococcal scalded-skin syndrome. In the first patient, at age 1 day the disease was recognized promptly by simple techniques such as Darier's sign and Tzanck smear. Much delay in making the diagnosis occurred in the other two patients, however: almost 1 year and 15 years, respectively. Bullous manifestations in mastocytosis occur only in the first two or three years. In the first months the disease can be dangerous and life threatening. To distinguish mastocytosis from vesicular and bullous neonatal disorders, one should perform Darier's sign and a Tzanck smear. The diagnosis is confirmed by histopathologic studies. Treatment of the bullous manifestations is symptomatic, with zinc oxide paste and oral antihistamines, which may provide some relief. In addition, cimetidine and sodium cromoglycate may be beneficial. At a later age psoralen plus ultraviolet A therapy may also relieve the symptoms. Particular foods and medicines can liberate histamine and should be restricted as much as possible in extremely affected patients. Special care should be taken when these patients are to undergo anesthesia. The risk of complications during and after anesthesia is also present in other forms of mastocytosis.