Urticaria pigmentosa. Histaminuria and treatment.

We present the case of an adult patient with urticaria pigmentosa. The sudden presence of severe symptomatology (symptoms to mast cell mediators release), made us think of evaluating extracutaneous affection. Our results are consistent with recent reports in the medical literature. We have confirmed an increase of conjugated histamine levels (methyl-histamine) during the attack and its return to normal values after the treatment. For these reasons we comment on the importance of histamine levels in diagnosis and treatment control. The gastrointestinal biopsy suggestive of mastocytosis; the severe clinical manifestations, and the histamine metabolite levels during the clinical course, led us to include this case in the group of "indolent SMCD" according to the TRAVIS classification.