Decrease of urticaria pigmentosa on cladribine. Remarkable reduction of urticaria pigmentosa lesions in patient A before treatment (A) and after 6 cycles of cladribine (B) and in patient D before treatment (C) and after 6 cycles of cladribine (D). Brown remnants of lesions are still seen after 6 months, consisting of predominantly melanocytes with hardly any mast cells present, confirmed in skin biopsies.