Treatment of urticaria pigmentosa using interferon alpha.

Long-term treatment with interferon alpha (IFN-alpha) has recently been shown to reduce the bone marrow infiltrate and cutaneous lesions in systemic mast cell disease. We therefore administered this cytokine to six patients with urticaria pigmentosa for up to 12 months, using subcutaneous injections of 5 x 10(6) U, initially five times, and subsequently three times a week. The generally well-tolerated therapy resulted in marked improvement of the cutaneous symptoms, especially in three of the patients who suffered from very severe pruritus. Two of the patients with bone marrow infiltration showed normal findings after treatment. However, in none of the patients was there any change in the skin lesions, or decrease in the degree of cutaneous mast cell infiltration, as evidenced by light and electron microscopic examination. These findings indicate that IFN-alpha is highly effective in the control of symptoms, but otherwise does not influence the cutaneous lesions of urticaria pigmentosa.