Photochemotherapy (PUVA) in the treatment of urticaria pigmentosa.

SUMMARY Eight patients received PUVA for mastocytosis. Five women had typical adult-onset urticaria pigmentosa, without evidence of systemic disease. Another woman had suspected hepatic involvement while the remaining female had early-onset familial urticaria pigmentosa with morphologically atypical mast cells. The only male patient had cirrhosis with hepatic deposits of mast cells in addition to polycythaemia rubra vera. In all patients, except the man with systemic disease, there was reduced pruritus and wealing and partial to almost complete fading of the macules. The manifestations of urticaria pigmentosa recurred after treatment was discontinued. In both lesional and uninvolved skin there was no significant change in either the mean mast cell counts or mast cell ultrastructure after an average of twenty-seven PUVA exposures. In addition, PUVA did not cause a significant alteration in the histamine content of the skin. The beneficial effect of PUVA in urticaria pigmentosa therefore does not appear to be directly related to a change in mast cell numbers or morphology, or to the histamine concentration in the skin. Urticaria pigmentosa usually presents as a generalized maculo-papular rash which urticates on rubbing (Darier's sign). Many patients are troubled only by the unsightliness of the rash while some complain of pruritus, wealing or flushing. These symptoms are attributed to the release of histamine by mast cells which characteristically occur in increased numbers in the dermis. Symptomatic treatment is often unrewarding, but favourable results have been claimed for cimetidine with or without Hi blockers (Hirschowitz & Groarke, 1979; O'Laughlin & Bredfeldt, 1980) and for oral disodium cromoglycate (Soter, Austen & Wasserman, 1979; Czarnetski & Behrendt, 1981). In 1978, Christophers and colleagues reported that photochemotherapy (PUVA) produced symptomatic relief in all of ten adult patients with typical urticaria pigmentosa. Similarly encouraging results were subsequently reported from other centres (Ortonne et al., 1980; Allevato, Donatti & Cordero, 1980; Granerus, Roupe & Swanbeck, 1981; Vaatainen, Hannuksela & Karvonen, 1981). In this study we examined the effects of PUVA in eight adult patients with urticaria pigmentosa. Although PUVA produced a moderately good clinical response in seven out of these eight patients (reduced pruritus, reduced wealing and faded macules) quantitative studies failed to reveal a consistent effect of PUVA on either the mast cell population density or the histamine concentration in both lesional and clinically uninvolved skin. The findings arc discussed in relation to existing information concerning the effect of ultraviolet radiation (U VR) on mast cells and other constituents of the skin.