Störungen der Melaninpigmentierung

Two unrelated patients with partial albinism, frequent pyogenic infections and acute episodes of fever, neutropenia and thrombocytopenia are described. Their pigmentary dilution was characterized by large clumps of pigments in the hair shafts and an accumulation of melanosomes in melanocytes. Melanocytes had few short dendritic expansions, and keratinocytes were hypopigmented. No or few Langerhans' cells were detected in skin by electron microscopy and ATP-ase reactions. This pigmentary dilution, different from all other human albinisms, resembles the unique defect of the mutant dilute (d-d) mouse. Despite the presence of an adequate number of T and B lymphocytes, the patients were hypogammaglobulinemic, deficient in antibody production and incapable of manifesting delayed skin hypersensitivity or of rejecting skin grafts. Their leukocytes did not stimulate normal lymphocytes and could not generate cytotoxic cells during mixed leukocyte reaction. T lymphocytes of one patient were unable to exert a helper effect on the maturation of B lymphocytes into immunoglobulin-containing cells following in vitro stimulation with pokeweed mitogen. This suggests that the humoral deficiency might be secondary to a defect of helper T lymphocytes. Granulocytes did not show any morphologic abnormality, and their bactericidal activity was only moderately reduced. An increased number of polymorphonuclear leukocytes with polar distribution of Concanavaline A (Con A) receptors (capping) was found in one patient and her parents. The family histories suggest that this syndrome is transmitted as an autosomal recessive character.

Melasma is a common acquired symmetric hypermelanosis characterized by irregular light- to gray-brown macules and patches involving sun-exposed areas of skin. Etiologic factors in the pathogenesis of melasma include genetic influences, exposure to UV radiation, pregnancy, hormonal therapies, cosmetics, phototoxic drugs, and antiseizure medications. Melasma is often a therapeutically challenging disease, and current treatments include hypopigmenting agents, chemical peels, and lasers. Hypopigmenting agents include phenolic and nonphenolic derivatives. Phenolic agents include hydroquinone and hydroquinone combination preparations. Despite controversies regarding the issue of hydroquinone-induced ochronosis, hydroquinone remains the most effective topically applied bleaching agent approved by the Food and Drug Administration for the treatment of melasma. Nonphenolic bleaching agents include tretinoin and azelaic acid. Superficial, medium, and deep chemical peels are more often used in lighter-complexioned patients. Such peels should be used with caution in blacks. Although lasers have demonstrated significant efficacy in the treatment of a variety of hyperpigmentary disorders, their precise efficacy and place in the therapy of melasma have yet to be established. In the hierarchy of therapies for melasma, the treating physician must consider the devastating psychosocial impact of pigmentary imperfections within the realm of the benefits and risks associated with each treatment.

To assess the safety and efficacy of topical 0.1% tacrolimus vs 0.05% clobetasol propionate. Randomized double-blind trial. Department of Dermatology, Hospital Central Dr Ignacio Morones Prieto, San Luis Potosí, México. From 20 children with vitiligo, 2 symmetrical lesions of about the same size and evolution time were selected. They were devoid of any topical or systemic therapy for 2 months prior to inclusion. Interventions Treatment with topical tacrolimus and clobetasol for a 2-month period. The grade of repigmentation was evaluated by color slides at baseline and again at every 2-week visit. The slides were analyzed by 2 clinicians unrelated to the study and by a morphometric digitalized computer program. Characteristics of pigment, time of response, symptoms, telangiectasias, and atrophy were evaluated every 2 weeks. Eighteen (90%) of the 20 patients experienced some repigmentation. The mean percentage of repigmentation was 49.3% for clobetasol and 41.3% for tacrolimus. Lesions in 3 patients using clobetasol presented atrophy, and 2 lesions incurred telangiectasias; tacrolimus caused a burning sensation in 2 lesions. Tacrolimus proved almost as effective as clobetasol propionate to restore skin color in lesions of vitiligo in children. Because it does not produce atrophy or other adverse effects, tacrolimus may be very useful for younger patients and for sensitive areas of the skin such as eyelids, and it should be considered in other skin disorders currently treated with topical steroids for prolonged periods.