Intermittent use of topical dimethyl sulfoxide in macular and papular amyloidosis

Background Severe and therapy-resistant pruritus is the most prominent feat ure of macular (MA) and lichen (LA) amyloidosis that leads to further amylo id deposition by recurrent frictional trauma to the epidermis. Of the vario us therapeutic modalities with variable success, the most encouraging and b eneficial effect has been observed with topical dimethyl sulfoxide (DMSO) t herapy. In a previous study, we achieved marked clinical improvement in nin e of 10 patients in a daily treatment regimen over 6-20 weeks, but relapses occurred in the post-treatment follow-up period. The aims of this study ar e to investigate whether the patients would benefit from intermittent thera py and to determine the optimal application interval of DMSO to maintain th e relief of symptoms. Methods Thirteen patients with histopathologically verified cutaneous amylo idosis (five MA, two LA and six biphasic) were enrolled in the study. They were treated once daily with a 50 or 100% DMSO solution until pruritus disa ppeared. Then, DMSO was applied at increasing intervals until the widest ef fective application interval for maintenance of relief was reached. Patient s were regularly followed-up by a scoring system for pruritus, papules, and pigmentation, control biopsies, photographs, blood biochemistry, and side- effects. Results The mean time required for the disappearance of pruritus was 4.1 we eks. Remarkable flattening of the papules was achieved after an average the rapy period of 9 weeks. After a total therapy period of 6.5 months, a nearl y 50% remission in pigmentation and >70% flattening of papules were achieve d. The widest effective DMSO application interval was 8.6 days. The side-ef fects of therapy were contact urticaria, desquamation, burning sensation, a nd garlic-like breath odor, which were more prominent with the higher conce ntration of DMSO, In interval therapy, side-effects were tolerated more eas ily than in daily therapy. No reduction of amyloid deposits was revealed in control biopsies. Conclusions Locally applied DMSO can break the vicious "pruritus-amyloid de position-pruritus" cycle in patients with MA and LA, In addition to its dai ly use, interval therapy seems to maintain this effect and enables patients to tolerate side-effects more easily.