Molluscum contagiosum infection associated with pimecrolimus use in pityriasis alba

Pityriasis Alba--Common Disease, Enigmatic Entity: Up-to-Date Review of the Literature

Pityriasis alba (PA) is a skin disorder that affects children and adolescents. Although it is common worldwide, its incidence is markedly higher in darker skin phototypes. Its characteristic features include an extended, multistage course and spontaneous remissions and recurrences. Preceded by erythematous changes, patches of hypopigmented skin of up to a few centimeters in diameter appear on the upper body. Pruritus may accompany it. Even though its etiology is unknown, possible reported triggering factors include sunlight, beauty treatments, and microorganisms, among others. Calcineurin inhibitors play the most crucial role in PA pharmacotherapy. PA often coexists with atopic dermatitis and is considered one of its milder forms.

Therapeutic implications of a barrier-based pathogenesis of atopic dermatitis

Excessive Th2 cell signaling and IgE production play key roles in the pathogenesis of atopic dermatitis (AD). Yet, recent information suggests that the inflammation in AD instead is initiated by inherited insults to the barrier, including a strong association between mutations in FILAGGRIN and SPINK5 in Netherton syndrome, the latter of which provides an important clue that AD is provoked by excess serine protease activity. But acquired stressors to the barrier may also be required to initiate inflammation in AD, and in addition, microbial colonization by Staphylococcus aureus both amplifies inflammation, but also further stresses the barrier in AD. Therapeutic implications of these insights are as follows: While current therapy has been largely directed toward ameliorating Th2-mediated inflammation and/or pruritus, these therapies are fraught with short-term and potential long-term risks. In contrast, "barrier repair" therapy, with a ceramide-dominant triple-lipid mixture of stratum corneum lipids, is more logical, of proven efficacy, and it provides a far-improved safety profile.

Double-blind, placebo-controlled, randomized study comparing 0.0003% calcitriol with 0.1% tacrolimus ointments for the treatment of endemic pityriasis alba

Background. Pityriasis alba (PA) is a frequent cause of consultation in tropical areas due to its chronic course, frequent relapses, and notorious hypopigmented lesions in pediatric dark skin populations. Currently, no treatment is widely accepted. Objective. To assess the efficacy of 0.0003% calcitriol and 0.1% tacrolimus ointments compared with placebo in the treatment of endemic PA. Methods. Twenty-eight children aged 3–17 years with 56 symmetrical lesions and phototype IV-V, were randomly assigned to receive the treatments on target lesions on the face. Improvement was evaluated at baseline and 8 weeks later clinically and by digital quantification of the affected area, colorimetry, and transepidermal water loss (TEWL). Results. Tacrolimus and calcitriol ointments induced a mean improvement of 68%, compared to 44% of placebo. We found an elevated TEWL in PA lesions. In the treated plaques, the reduction of the affected area was associated with improvement of pigmentation and TEWL. Conclusions. Calcitriol and tacrolimus induced similar repigmentation in endemic PA lesions. Melanogenic, anti-inflammatory, and barrier defect restoration properties of these drugs may explain these findings.

Estudo da correlação entre molusco contagioso e dermatite atópica em crianças

FUNDAMENTOS: É bastante divulgado, sem a fundamentação científica necessária, que a infecção por molusco contagioso tende a ser mais frequente e de maior intensidade nos pacientes acometidos por dermatite atópica. Tal fato motivou a realização deste trabalho. OBJETIVOS: Avaliar a prevalência de associação de dermatite atópica e molusco contagioso; avaliar se, nos pacientes com dermatite atópica, a infecção por molusco contagioso é mais recorrente e/ou disseminada e se a ocorrência de eczema perimolusco, prurido e/ou infecção é mais prevalente que nos pacientes sem dermatite atópica. MÉTODOS: Avaliaram-se 284 crianças de ambos os sexos, com diagnóstico de molusco contagioso e/ ou dermatite atópica. RESULTADOS: Apenas 13,4% dos pacientes apresentavam ambas as doenças. O número de áreas anatômicas afetadas por molusco contagioso, a ocorrência de eczema perimolusco e prurido foram maiores nos pacientes com dermatite atópica associada. Não houve diferença significativa de frequência de infecção secundária associada às lesões de molusco contagioso nos pacientes com e sem dermatite atópica. CONCLUSÃO: A prevalência da ocorrência de dermatite atópica e molusco contagioso associados foi baixa. Não houve diferença significativa na recorrência da infecção por molusco contagioso e na quantidade de lesões nos pacientes com e sem dermatite atópica. O número de áreas anatômicas afetadas por lesões de molusco contagioso, a presença de eczema perimolusco e de prurido foram maiores nos pacientes com dermatite atópica. Não houve diferença significativa na ocorrência de infecção bacteriana secundária nos grupos com e sem dermatite atópica

Topical calcineurin inhibitors compromise stratum corneum integrity, epidermal permeability and antimicrobial barrier function

BACKGROUND

Topical calcineurin inhibitors (TCIs) such as pimecrolimus and tacrolimus have recently been used for dermatologic diseases including atopic dermatitis instead of topical glucocorticoids, because they display comparable efficacy, but less-frequent side effects. Although even short-term topical glucocorticoid compromise epidermal permeability barrier homeostasis, the effects of TCI on barrier function have not yet been reported. However, viral infections such as eczema herpeticum and molluscum contagiosum, which could indicate an impaired skin barrier, continue to occur with TCI use in atopic dermatitis.

OBJECTIVES

We determined here whether TCIs disrupt epidermal permeability barrier and antimicrobial function, and whether these effects can be prevented.

METHODS AND RESULTS

In normal humans, topical pimecrolimus and tacrolimus applied twice-daily for 5 days, delay barrier recovery without an increase in basal transepidermal water loss was observed. Co-application of physiologic lipid mixture (PLM) containing an equimolar ratio of ceramides, cholesterol and free fatty acids normalized barrier homeostasis in the face of topical TCIs. In hairless mice, 4 days of TCI treatment also disrupted barrier function significantly. TCIs-treated epidermis showed the decrease of epidermal lipid content, lamellar body number and secretion, and lipid synthesis-related enzymes such as 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, serine-palmitoyl transferase and fatty acid synthase, implying decreased lipid synthesis. TCIs also suppressed expression of IL-1alpha and antimicrobial peptides, CRAMP and mouse beta-defensin 3. However, these TCI-induced abnormalities can be overridden by topical replacement with PLM.

CONCLUSIONS

Our results demonstrate that TCIs induce negative effects on the skin barrier including permeability and antimicrobial functions, which are mediated by decreasing epidermal lipid synthesis, lamellar body secretion and antimicrobial peptides expression through suppression of cytokine such as IL-1alpha, therefore co-treatment with PLM would be helpful to overcome these negative effects.