No abstract

Progressive macular hypomelanosis (PMH) is a common skin disorder that is often misdiagnosed. Various authors have written about similar skin disorders, referring to them by different names, but we believe that all these similar disorders are part of the same entity.PMH is characterized by ill-defined nummular, non-scaly hypopigmented spots on the trunk, often confluent in and around the midline, and rarely extending to the proximal extremities and neck/head region. There is no itch, pain, or preceding inflammation. PMH has a worldwide distribution; however, it is more often identified in Black people living in or originating from tropical countries. It is also more often seen in young females. The natural history of PMH is stable disease or perhaps slow progression over decades, with spontaneous disappearance after mid-life. Extensive pityriasis alba is probably identical with PMH and we suggest discontinuation of use of the former term on the grounds that extensive pityriasis alba is histologically and clinically different from classical pityriasis alba, which is basically an eczematous type of disorder.PMH is characterized histologically by diminished pigment in the epidermis and a normal-looking dermis. Electron microscopy shows a shift from large melanosomes in normal-looking skin to small aggregated, membrane-bound melanosomes in hypopigmented skin. PMH should be differentiated from other disorders with hypopigmentation on the trunk such as pityriasis versicolor. We propose that Propionibacterium acnes bacteria living in hair follicles are the cause of PMH as a result of production of a hypothetical depigmenting factor. This hypothesis is based on: (i) the presence of a red follicular fluorescence in the hypopigmented spots and the absence of this phenomenon in normal skin when examined under a Wood's light in a dark room; (ii) cultivation of P. acnes from the follicles in the hypopigmented spots but not from follicles in normal-looking skin; and (iii) improvement of the disorder after elimination of these micro-organisms with topical antimicrobial treatment in combination with UVA light.Currently, the treatment of choice of PMH is application of 1% clindamycin lotion during the daytime, 5% benzoyl peroxide gel at night-time, and UVA light irradiation three times a week for a period of 12 weeks. There is insufficient information available as yet to comment on the recurrence rate after therapy.

No abstract

Vitiligo development in melanoma patients during immunotherapy is a favorable prognostic sign and indicates breakage of tolerance against melanocytic/melanoma antigens. We investigated a novel immunotherapeutic approach of the skin-depigmenting compound monobenzone synergizing with imiquimod in inducing antimelanoma immunity and melanoma regression. Stage III-IV melanoma patients with non-resectable cutaneous melanoma metastases were treated with monobenzone and imiquimod (MI) therapy applied locally to cutaneous metastases and adjacent skin during 12 weeks, or longer. Twenty-one of 25 enrolled patients were evaluable for clinical assessment at 12 weeks. MI therapy was well-tolerated. Partial regression of cutaneous metastases was observed in 8 patients and stable disease in 1 patient, reaching the statistical endpoint of treatment efficacy. Continued treatment induced clinical response in 11 patients, including complete responses in three patients. Seven patients developed vitiligo-like depigmentation on areas of skin that were not treated with MI therapy, indicating a systemic effect of MI therapy. Melanoma-specific antibody responses were induced in 7 of 17 patients tested and melanoma-specific CD8+T-cell responses in 11 of 15 patients tested. These systemic immune responses were significantly increased during therapy as compared to baseline in responding patients. This study shows that MI therapy induces local and systemic anti-melanoma immunity and local regression of cutaneous metastases in 38% of patients, or 52% during prolonged therapy. This study provides proof-of-concept of MI therapy, a low-cost, broadly applicable and well-tolerated treatment for cutaneous melanoma metastases, attractive for further clinical investigation.