Phototherapy of urticaria pigmentosa: Clinical response and changes of cutaneous reactivity,histamine and chemotactic leukotrienes

Summary Ten patients with moderate to very severe urticaria pigmentosa were studied for the therapeutic effect of photochemotherapy (PUVA; six adults) and selective ultraviolet phototherapy (SUP; four adolescents). Despite a high mean PUVA dosage (138.6 ±63.4 J/cm²), only two patients had a very good response, while three had a good response and one had a fair response. On the reduction of the frequency of treatments, the symptoms gradually recurred, and several months after the discontinuation of therapy, the clinical status had reached the level prior to PUVA. The results with SUP were even less encouraging. A number of biophysical and biochemical parameters of the skin were studied in five patients before PUVA treatment, immediately after several months of PUVA treatment and again 5 months after the discontinuation of PUVA treatment. Weal and erythema reactions to intracutaneous skin tests remained unchanged after PUVA, while wealing with topically applied dimethylsulfoxide (DMSO) decreased. Transepidermal water loss was markedly reduced over DMSO weals. Histamine levels, which were elevated in lesional but not in normal skin, dropped with PUVA treatment, but after the discontinuation of treatment, they increased again in the lesions. On reverse-phase high-performance liquid chromatography, two main chemotactic factors, leukotriene B₄ and 5-HETE, were identified in lesional skin. Chemotactic activity was elevated in both lesional and uninvolved patient skin, reached normal levels at both sites after PUVA and maintained these low levels for several months after the discontinuation of treatment. Our data suggest that PUVA has reversible anti-inflammatory effects on human skin, because it increases epidermal-barrier function and decreases the synthesis of mediators of inflammation. These observations show the transitory therapeutic benefit of PUVA in patients with urticaria pigmentosa.