589 Urticaria Pigmentosa. Case Report

BACKGROUND: Mastocytosis is a disorder characterized by an abnormal proliferation of mast cells and release of cell mediators. The incidence is 1 per 1000 skin diseases attending in dermatology services. Mastocytosis can be divided into 3 different clinical variants: cutaneous, systemic and malign mastocytosis. Urticaria pigmentosa is the most common variety (70–90%) of mastocytosis. Of all cases 55% ocurr during the first 2 years of life. When the bone marrow, lymph nodes, liver and spleen are affected the disorder is called systemic mastocytosis. METHODS: Case 1: A 20 month old male with history of penicillin and erythromycin allergy, as well atopic family history. Began at 4 months with itchy brown-marrow papules in the back, then generalizated except palms and soles. The lesions were exacerbated by heat and rubbing. There was no fever, weight loss, or any other systemic symptoms in the history. Blood count and biochemical laboratories were normal. Skin biopsy reported the presence of mast cells, confirming urticaria pigmentosa diagnosis. The management included antihistamines, restricted diet and emollients with improved of symptoms. Case 2: A 9 month old male with no history of atopy. At the first visit he had 4 months with skin lesions characterized by hyperpigmented maculopapular eruption, scattered on head, over trunk and extremities. Darier´s sign was positive. Skin biopsy is performed with confirming the diagnosis of mastocytosis. CONCLUSIONS: The urticaria pigmentosa diagnosis is mainly clinical, with emphasis on the Darier´s sign, which is pathognomonic and positive in 90% of cases. In some cases a skin biopsy is required to confirm the diagnosis. Antihistamines are the first line of treatment. Symptoms relieve spontaneously before adolescence in 50% of pediatric patients. In some cases, a malignant transformation of mastocytosis could occur, condition that is called “mast cell leukemia”.