Effect of topical tazarotene in the treatment of congenital ichthyoses

French national protocol for the management of congenital ichthyosis

Congenital ichthyoses (CI) comprise a heterogeneous group of monogenic genetic skin diseases characterized by diffuse scaling, often associated with skin inflammation. Diagnosis of the individual form of ichthyosis is complex and is guided by clinical expertise. CI usually has a major impact on quality of life (QOL) and thus requires lifelong treatment. To date, there are no curative therapies, although various symptomatic treatment options exist. The present protocol for the management of CI has been drawn up in accordance with the recommendations published in 2012 by the French National Authority for Health, based on a literature review, with the help and validation of members of the French network for rare skin diseases (FIMARAD). It provides a summary of evidence and expert-based recommendations and is intended to help clinicians with the management of these rare and often complex diseases.

Drug screening identifies tazarotene and bexarotene as therapeutic agents in multiple sulfatase deficiency

Multiple sulfatase deficiency (MSD, MIM #272200) results from pathogenic variants in the SUMF1 gene that impair proper function of the formylglycine-generating enzyme (FGE). FGE is essential for the posttranslational activation of cellular sulfatases. MSD patients display reduced or absent sulfatase activities and, as a result, clinical signs of single sulfatase disorders in a unique combination. Up to date therapeutic options for MSD are limited and mostly palliative. We performed a screen of FDA-approved drugs using immortalized MSD patient fibroblasts. Recovery of arylsulfatase A activity served as the primary readout. Subsequent analysis confirmed that treatment of primary MSD fibroblasts with tazarotene and bexarotene, two retinoids, led to a correction of MSD pathophysiology. Upon treatment, sulfatase activities increased in a dose- and time-dependent manner, reduced glycosaminoglycan content decreased and lysosomal position and size normalized. Treatment of MSD patient derived induced pluripotent stem cells (iPSC) differentiated into neuronal progenitor cells (NPC) resulted in a positive treatment response. Tazarotene and bexarotene act to ultimately increase the stability of FGE variants. The results lay the basis for future research on the development of a first therapeutic option for MSD patients.

Ichthyosis

The ichthyoses are a large, heterogeneous group of skin cornification disorders. They can be inherited or acquired, and result in defective keratinocyte differentiation and abnormal epidermal barrier formation. The resultant skin barrier dysfunction leads to increased transepidermal water loss and inflammation. Disordered cornification is clinically characterized by skin scaling with various degrees of thickening, desquamation (peeling) and erythema (redness). Regardless of the type of ichthyosis, many patients suffer from itching, recurrent infections, sweating impairment (hypohidrosis) with heat intolerance, and diverse ocular, hearing and nutritional complications that should be monitored periodically. The characteristic clinical features are considered to be a homeostatic attempt to repair the skin barrier, but heterogeneous clinical presentation and imperfect phenotype-genotype correlation hinder diagnosis. An accurate molecular diagnosis is, however, crucial for predicting prognosis and providing appropriate genetic counselling. Most ichthyoses severely affect patient quality of life and, in severe forms, may cause considerable disability and even death. So far, treatment provides only symptomatic relief. It is lifelong, expensive, time-consuming, and often provides disappointing results. A better understanding of the molecular mechanisms that underlie these conditions is essential for designing pathogenesis-driven and patient-tailored innovative therapeutic solutions.

Treatments for Non-Syndromic Inherited Ichthyosis, Including Emergent Pathogenesis-Related Therapy

The term 'inherited ichthyosis' refers to a heterogeneous group of mendelian disorders of cornification that involve the integument with varying degrees of scaling. The management of ichthyosis poses a challenge for most physicians. Treatment options proposed in the literature include moisturizers, topical keratolytics, topical and systemic vitamin D analogues, and topical and systemic retinoids; however, some of these modalities are less reliable than others. Despite the therapeutic impasse imposed by the options above, the emergence of pathogenesis-based treatments along with novel gene therapies appear promising and hold the potential to halt or even revert disorders that arise from single genetic mutations, although research is still quite lacking in this domain. Hence, this review aims to highlight the various treatment modalities available for the management of the cutaneous manifestations of non-syndromic inherited ichthyosis, with an added emphasis on pathogenesis-targeted therapies.

Consensus recommendations for the use of retinoids in ichthyosis and other disorders of cornification in children and adolescents

Topical and systemic retinoids have long been used in the treatment of ichthyoses and other disorders of cornification. Due to the need for long-term use of retinoids for these disorders, often beginning in childhood, numerous clinical concerns must be considered. Systemic retinoids have known side effects involving bone and eye. Additionally, potential psychiatric and cardiovascular effects need to be considered. Contraceptive concerns, as well as the additive cardiovascular and bone effects of systemic retinoid use with hormonal contraception must also be deliberated for patients of childbearing potential. The Pediatric Dermatology Research Alliance (PeDRA) Use of Retinoids in Ichthyosis Work Group was formed to address these issues and to establish best practices regarding the use of retinoids in ichthyoses based on available evidence and expert opinion.

Management of congenital ichthyoses: European guidelines of care, part one

These guidelines for the management of congenital ichthyoses have been developed by a multidisciplinary group of European experts following a systematic review of the current literature, an expert conference held in Toulouse in 2016 and a consensus on the discussions. They summarize evidence and expert-based recommendations and are intended to help clinicians with the management of these rare and often complex diseases. These guidelines comprise two sections. This is part one, covering topical therapies, systemic therapies, psychosocial management, communicating the diagnosis and genetic counselling.

Nonclinical and human pharmacology of the potent and selective topical retinoic acid receptor-γ agonist trifarotene

BACKGROUND

First- and third-generation retinoids are the main treatment for acne. Even though efficacious, they lack full selectivity for retinoic acid receptor (RAR) γ, expressed in the epidermis and infundibulum.

OBJECTIVES

To characterize the in vitro metabolism and the pharmacology of the novel retinoid trifarotene.

MATERIALS AND METHODS

In vitro assays determined efficacy, potency and selectivity on RARs, as well as the activity on the expression of retinoid target genes in human keratinocytes and ex vivo cultured skin. In vivo studies investigated topical comedolytic, anti-inflammatory and depigmenting properties. The trifarotene-induced gene expression profile was investigated in nonlesional skin of patients with acne and compared with ex vivo and in vivo models. Finally, the metabolic stability in human keratinocytes and hepatic microsomes was established.

RESULTS

Trifarotene is a selective RARγ agonist with > 20-fold selectivity over RARα and RARβ. Trifarotene is active and stable in keratinocytes but rapidly metabolized by human hepatic microsomes, predicting improved safety. In vivo, trifarotene 0·01% applied topically is highly comedolytic and has anti-inflammatory and antipigmenting properties. Gene expression studies indicated potent activation of known retinoid-modulated processes (epidermal differentiation, proliferation, stress response, retinoic acid metabolism) and novel pathways (proteolysis, transport/skin hydration, cell adhesion) in ex vivo and in vivo models, as well as in human skin after 4 weeks of topical application of trifarotene 0·005% cream.

CONCLUSIONS

Based on its RARγ selectivity, rapid degradation in human hepatic microsomes and pharmacological properties including potent modulation of epidermal processes, topical treatment with trifarotene could result in good efficacy and may present a favourable safety profile in acne and ichthyotic disorders.

Ocular manifestations, complications and management of congenital ichthyoses: a new look

Congenital ichthyoses (CI) are rare genetic skin keratinisation diseases characterised by generalised scaling and a variable degree of erythema and hyperkeratosis. Ocular involvement includes the eyelids, conjunctiva and all layers of the cornea. Ophthalmic input should include regular slit lamp review with the primary aim to prevent a corneal epithelial defect, secondary bacterial infection, scarring or perforation. This review highlights the current literature regarding ophthalmic findings and management of CI.

Ectropion Improvement with Topical Tazarotene in Children with Lamellar Ichthyosis

BACKGROUND/OBJECTIVES

Lamellar ichthyosis (LI) is a well-described phenotypic subtype of autosomal recessive congenital ichthyosis (ARCI). The condition typically presents at birth with collodion membrane and leads to thick, plate-like scaling of the skin throughout the body, alopecia, and prominent ocular manifestations. Ocular complications include bilateral cicatricial ectropion and lagophthalmos. These ocular complications can lead to chronic exposure keratitis and in some cases corneal ulceration and blindness. No cure for ichthyosis exists. Treatment of ocular complications in LI includes surgical correction, systemic retinoids, and a variety of topical therapies such as emollients, keratolytics, and retinoids.

METHODS

Five children with LI cared for at our institution were identified and included. Patient age at the start of therapy ranged from 2 weeks to 9 years. Electronic medical records were reviewed and data from pediatric dermatologist and pediatric ophthalmologist visits were obtained. Data were collected before and after treatment of daily or twice-daily 0.05% to 0.1% tazarotene cream applied to the face and eyelids.

RESULTS

All patients had improvement in the degree of ectropion, with complete resolution in two of the five patients. The two patients with lagophthalmos at the time of tazarotene initiation experienced complete resolution. No adverse effects were reported.

CONCLUSIONS

Tazarotene cream appears to be effective in the management of ectropion and lagophthalmos in the setting of LI in children, even in the neonatal period.

Genetics and prospective therapeutic targets for Sjögren-Larsson Syndrome

INTRODUCTION

Sjögren-Larsson syndrome (SLS) is a rare neurocutaneous disease characterized by ichthyosis, spasticity, intellectual disability and a distinctive retinopathy. It is caused by inactivating mutations in ALDH3A2, which codes for fatty aldehyde dehydrogenase (FALDH) and results in abnormal metabolism of long-chain aliphatic aldehydes and alcohols. The potential disease mechanisms leading to symptoms include 1) accumulation of toxic fatty aldehydes that form covalent adducts with lipids and membrane proteins; 2) physical disruption of multi-lamellar membranes in skin and brain; 3) abnormal activation of the JNK cell signaling pathway; and 4) defective farnesol metabolism resulting in abnormal PPAR-α dependent gene expression. Currently, no effective pathogenesis-based therapy is available.

AREAS COVERED

The clinical, pathologic and genetic features of SLS are summarized. The biochemical abnormalities caused by deficient activity of FALDH are reviewed in the context of proposed pathogenic mechanisms and potential therapeutic interventions.

EXPERT OPINION

The most promising pharmacologic approach to SLS involves blocking the formation of potentially harmful fatty aldehyde adducts using aldehyde scavenging drugs, currently in phase 2 clinical trials. Other approaches needing further investigation include: 1) ALDH-specific activator drugs and PPAR-α agonists to increase mutant FALDH activity; 2) inhibitors of the JNK phosphorylation cascade; 3) antioxidants to decrease aldehyde load; 4) dietary lipid modification; and 5) gene therapy.

Ocular manifestations of genetic skin disorders

Genetic skin diseases, or genodermatoses, often have extracutaneous manifestations. Ocular manifestations in particular can have significant clinical implications, like blindness. Other manifestations, such as the corneal opacities that occur in X-linked ichthyosis, are asymptomatic but characteristic of a particular genodermatosis. Ophthalmologic examination can aid in diagnosis when characteristic findings are seen. The genodermatoses with ocular manifestations will be reviewed, but neurocutaneous, syndromes, genetic pigmentary disorders, and genetic metabolic diseases are not included because they are covered elsewhere in this issue.

Ichthyosis with confetti: clinics, molecular genetics and management

Ichthyosis with confetti (IWC) is an autosomal dominant congenital ichthyosis also known as ichthyosis variegata or congenital reticular ichthyosiform erythroderma. It manifests at birth with generalized ichthyosiform erythroderma or with a collodion baby picture. The erythrodermic and ichthyotic phenotype persists during life and its severity may modify. However, the hallmark of the disease is the appearance, in childhood or later in life, of healthy skin confetti-like spots, which increase in number and size with time. IWC is a very rare genodermatosis, with a prevalence <1/1,000,000 and only 40 cases reported worldwide. The most important associated clinical features include ear deformities, mammillae hypoplasia, palmoplantar keratoderma, hypertrichosis and ectropion. IWC is due to dominant negative mutations in the KRT10 and KRT1 genes, encoding for keratins 10 and keratin 1, respectively. In this context, healthy skin confetti-like spots represent “repaired” skin due to independent events of reversion of keratin gene mutations via mitotic recombination. In most cases, IWC clinical suspicion is delayed until the detection of white skin spots. Clinical features, which may represent hint to the diagnosis of IWC even before appearance of confetti-like spots, include ear and mammillae hypoplasia, the progressive development of hypertrichosis and, in some patients, of adherent verrucous plaques of hyperkeratosis. Altogether the histopathological finding of keratinocyte vacuolization and the nuclear staining for keratin 10 and keratin 1 by immunofluorescence are pathognomonic. Nevertheless, mutational analysis of KRT10 or KRT1 genes is at present the gold standard to confirm the diagnosis. IWC has to be differentiated mainly from congenital ichthyosiform erythroderma. Differential diagnosis also includes syndromic ichthyoses, in particular Netherton syndrome, and the keratinopathic ichthyoses. Most of reported IWC cases are sporadic, but familial cases with autosomal dominant mode of inheritance have been also described. Therefore, knowledge of the mutation is the only way to properly counsel the couples. No specific and satisfactory therapy is currently available for IWC. Like for other congenital ichthyoses, topical treatments (mainly emollients and keratolytics) are symptomatic and offer only temporary relief. Among systemic treatments, retinoids, in particular acitretin, improve disease symptoms in most patients. Although at present there is no curative therapy for ichthyoses, treatments have improved considerably over the years and the best therapy for each patient is always the result of both physician and patient efforts.

Topical enzyme-replacement therapy restores transglutaminase 1 activity and corrects architecture of transglutaminase-1-deficient skin grafts

Transglutaminase-1 (TG1)-deficient autosomal-recessive congenital ichthyosis (ARCI) is a rare and severe genetic skin disease caused by mutations in TGM1. It is characterized by collodion babies at birth, dramatically increased transepidermal water loss (TEWL), and lifelong pronounced scaling. The disease has a tremendous burden, including the problem of stigmatization. Currently, no therapy targeting the molecular cause is available, and the therapeutic situation is deplorable. In this study, we developed the basis for a causative therapy aiming at the delivery of the enzyme to the inner site of the keratinocytes' plasma membrane. We prepared sterically stabilized liposomes with encapsulated recombinant human TG1 (rhTG1) and equipped with a highly cationic lipopeptide vector to mediate cellular uptake. The liposomes overcame the problems of insufficient cutaneous delivery and membrane penetration and provided excellent availability and activity of rhTG1 in primary keratinocytes. To demonstrate the general feasibility of this therapeutic approach in a humanized context, we used a skin-humanized mouse model. Treatment with rhTG1 liposomes resulted in considerable improvement of the ichthyosis phenotype and in normalization of the regenerated ARCI skin: in situ monitoring showed a restoration of TG1 activity, and cholesterol clefts vanished ultrastructurally. Measurement of TEWL revealed a restoration of epidermal barrier function. We regard this aspect as a major advance over available nonspecific approaches making use of, for example, retinoid creams. We conclude that this topical approach is a promising strategy for restoring epidermal integrity and barrier function and provides a causal cure for individuals with TG1 deficiency.

Topical tazarotene for the treatment of ectropion in ichthyosis

IMPORTANCE

Ectropion is a complication of certain subtypes of ichthyosis and is often associated with substantial medical and cosmetic consequences. At present there is no standard of care for the treatment of ectropion in this population. Retinoids cause dyshesion and thinning of stratum corneum, thereby reducing hyperkeratosis that likely underlies ectropion in patients with ichthyosis. As such, retinoids provide a potential effective treatment for ectropion in this group of patients.

OBSERVATION

We describe a patient with recessive ichthyosis for whom daily application of topical tazarotene produced rapid and persistent improvement of bilateral lower eyelid ectropion without adverse effects.

CONCLUSIONS AND RELEVANCE

Additional studies will be necessary to more fully and systematically address the safety and efficacy of topical retinoids for the treatment of ectropion in patients with ichthyosis; however, this case illustrates that topical tazarotene and other retinoids provide a potential treatment option for ectropion in this population. We encourage clinicians to explore medical therapies as alternatives to surgical intervention for the treatment of ectropion in patients with ichthyosis.

Topical treatment of ichthyoses

Management of ichthyoses is a complex and continuously dynamic process. Primary treatments of ichthyosis are by means of topical moisturizers and topical medications. Patients and families need to have reasonable and realistic expectations when it comes to topical therapy. Topical medications cannot cure the scaling, but can gradually reduce it and thus improve their condition. No one treatment regimen works for everyone, and the best topical therapy for each patient may be the result of months (or years) of painstaking effort on both the physician's and the patient's behalf. As patients get older and their activities and lifestyles change, so should their topical treatment regimen. Bear in mind that the more complex the skin care regimen and costly the topical treatments, the less likely a patient and their family will be compliant.

A systematic review of clinical trials of treatments for the congenital ichthyoses, excluding ichthyosis vulgaris

BACKGROUND

The ichthyoses comprise a group of inherited disorders of keratinization. Because of the need for lifelong treatment, it is important that therapies are beneficial, safe, and well tolerated.

OBJECTIVES

We sought to review the evidence on existing treatments for the congenital ichthyoses, excluding ichthyosis vulgaris.

METHOD

We undertook a systematic review using the methodology of the Cochrane Collaboration. Articles published in MEDLINE, EMBASE, and CENTRAL and registered clinical trials were screened. Randomized controlled trials involving patients with the inherited ichthyoses, either syndromic or nonsyndromic but excluding ichthyosis vulgaris, were considered.

RESULTS

Six trials met the inclusion criteria. Topical treatments including 5% urea, 20% propylene glycol alone or in combination with 5% lactic acid, calcipotriol ointment, and liarozole 5% cream showed therapeutic benefit. Oral liarozole, a retinoic acid metabolism blocking agent, showed no advantage over oral acitretin.

LIMITATIONS

Most studies were performed on a small sample of patients and lacked methodological and reporting quality. The small number of trials and the nearly constant positive results make publication bias likely. The absence of standardization of outcome measures precluded the comparison of studies.

CONCLUSIONS

Topical treatments including emollients, calcipotriol ointment, and liarozole cream seem to have therapeutic benefit and a good safety profile, although the use of topical calcipotriol is limited by a maximum weekly dose of 100 g. The advantage of oral liarozole over acitretin is uncertain. Multicenter trials comparing oral and topical interventions and evaluation of long-term outcomes are needed.

Autosomal recessive congenital ichthyosis

The term autosomal recessive congenital ichthyosis (ARCI) refers to a group of rare disorders of keratinization classified as nonsyndromic forms of ichthyosis. This group was traditionally divided into lamellar ichthyosis (LI) and congenital ichthyosiform erythroderma (CIE) but today it also includes harlequin ichthyosis, self-healing collodion baby, acral self-healing collodion baby, and bathing suit ichthyosis. The combined prevalence of LI and CIE has been estimated at 1 case per 138 000 to 300 000 population. In some countries or regions, such as Norway and the coast of Galicia, the prevalence may be higher due to founder effects. ARCI is genetically highly heterogeneous and has been associated with 6 genes to date: TGM1, ALOXE3, ALOX12B, NIPAL4, CYP4F22, and ABCA12. In this article, we review the current knowledge on ARCI, with a focus on clinical, histological, ultrastructural, genetic, molecular, and treatment-related aspects.

Successful experimental treatment of congenital ichthyosis in an infant

Ichthyosis is a rare genetic disease that causes defects in skin keratinisation. Infants born with this disease have tight shiny skin that inhibits limb and ear mobilities, eyelid and lip deformities and poor hair and nail growths. In addition, the barrier properties of the skin are disrupted, which leads to dehydration, body temperature regulation difficulties and increased susceptibility to infection. The treatments currently available include topical keratolytics, emollients, and for severe disease systemic retinoids. Given the increased permeability of the skin and increased body surface area infants are particularly susceptible to accidental overdose from the topical keratolytic treatments currently available. An experimental emollient of 10% N-acetylcysteine (NAC) and 5% urea was recently used with success in Argentina. A newborn with congenital ichthyosis cared for in our clinic failed his initial treatment of topical emollients. He was subsequently treated successfully with off-label use of a topical 5% NAC and 5% urea emollient.

X-linked ichthyosis: an oculocutaneous genodermatosis

X-linked ichthyosis (XLI) is an X-linked recessive disorder of cutaneous keratinization with possible extracutaneous manifestations. It was first described as a distinct type of ichthyosis in 1965. XLI is caused by a deficiency in steroid sulfatase activity, which results in abnormal desquamation and a retention hyperkeratosis. XLI is usually evident during the first few weeks of life as polygonal, loosely adherent translucent scales in a generalized distribution that desquamate widely. These are quickly replaced by large, dark brown, tightly adherent scales occurring primarily symmetrically on the extensor surfaces and the side of the trunk. In addition, extracutaneous manifestations such as corneal opacities, cryptorchidism, and abnormalities related to contiguous gene syndromes may be observed. Diagnosis of XLI is usually made clinically, as the histopathology is nonspecific, but confirmation may be obtained through either biochemical or genetic analysis. Treatment should focus on cutaneous hydration, lubrication, and keratolysis and includes topical moisturizers and topical retinoids.

Ichthyosis: clinical manifestations and practical treatment options

Ichthyoses constitute a large group of cornification disorders that affect the entire integument. The skin is characterized by visible scaling and in many cases by inflammation, for example, in bullous/keratinopathic ichthyosis or Netherton syndrome. From the viewpoint of classification it is useful to distinguish non-syndromic from syndromic types of ichthyosis. Ichthyosis vulgaris and recessive X-linked ichthyosis are common disorders - often of delayed onset, in contrast to congenital ichthyoses, which belong to the group of rare diseases and present at birth with either the features of collodion membrane or congenital ichthyosiform erythroderma. The diagnostic steps are based on clinical data, analyses such as the steroid sulfatase activity test, skin biopsies, and genetic results. However, the dramatic increase in knowledge about the pathophysiology of these conditions has not led to a curative therapy so far. The therapeutic management is multidisciplinary and involves ichthyosis patient organizations in many countries. The mainstay of treatment remains with moisturizing creams containing, for example, urea, lactic acid and other humectants and keratolytics, regular bathing, and mechanical scale removal. Patients with lamellar ichthyosis or ichthyosiform erythroderma in particular profit from oral therapy with retinoids or retinoic acid metabolism-blocking agents.

Oral liarozole vs. acitretin in the treatment of ichthyosis: a phase II/III multicentre, double-blind, randomized, active-controlled study

BACKGROUND

Liarozole, a retinoic acid metabolism blocking agent, has been granted orphan drug status for congenital ichthyosis by the European Commission and the U.S. Food and Drug Administration.

OBJECTIVES

The purpose of this trial was to investigate the efficacy, tolerability and safety of oral liarozole vs. acitretin in patients with ichthyosis.

METHODS

In this double-blind comparative trial of liarozole vs. acitretin, 32 patients with ichthyosis were randomized to be treated with either oral liarozole 75 mg in the morning and 75 mg in the evening or with acitretin 10 mg in the morning and 25 mg in the evening for 12 weeks. Clinical efficacy, tolerability and safety were monitored.

RESULTS

Between-group comparisons for efficacy and tolerability revealed no statistically significant differences except for scaling on the trunk at baseline which was significantly worse in the liarozole group (P = 0.024) and showed a more pronounced improvement in this group than in the acitretin-treated patients (P = 0.047). Based on the overall evaluation of the response to treatment at endpoint, 10 of 15 patients in the liarozole group and 13 of 16 patients in the acitretin group were considered by the investigator to be at least markedly improved. The expected retinoic acid-related adverse events were mostly mild to moderate and tended to occur less frequently in the liarozole group. No serious adverse events related to the drugs occurred.

CONCLUSIONS

The present study indicates that liarozole at a daily dose of 150 mg is equally effective as a treatment for ichthyosis as acitretin but shows a trend towards a more favourable tolerability profile. The results of this trial warrant further clinical trials to confirm efficacy and safety of liarozole as an orphan drug in ichthyosis.

Erythrokeratoderma variabilis successfully treated with topical tazarotene

Erythrokeratoderma variabilis, also known as Mendes da Costa syndrome, is a genodermatosis belonging to the group of diseases known as the erythrokeratodermias. Erythrokeratoderma variabilis is characterized by two distinctive manifestations: well-demarcated, variable, transient, figurate patches of erythema, and localized or generalized hyperkeratotic plaques. Treatments include topical retinoic acid, salicylic acid, and alpha-hydroxy acid in petrolatum, but all have been reported to have limited, variable success rates. We report a child with erythrokeratoderma variabilis with no family history of this entity, successfully treated with topical tazarotene.

Neonatal skin barrier: structure, function, and disorders

The development of the human skin from intrauterine to extrauterine life is a balletic interplay of maturing layers and interlocking structures. We discuss this transition and then branch out to touch on issues of premature infant as well as neonatal skin care. Disruption of the barrier function due to toxins and development errors are expounded upon. Staph scalded skin syndrome, collodion membrane, bullous congenital ichthyosiform erythroderma, autosomal recessive ichthyosis (lamellar and congenital ichthyosiform erythroderma), and harlequin fetus are used as examples of these disruptions. Discussion of therapy with the authors' experience highlights each disease.

The p73 gene is an anti-tumoral target of the RARbeta/gamma-selective retinoid tazarotene

Tazarotene, a member of the new class of acetylenic retinoids, has been shown to be effective in the treatment of several hyperproliferative skin diseases, including non-melanoma skin cancer. Its effectiveness is thought to rely on the ability to activate retinoic acid receptors beta and gamma and to induce a number of downstream anti-proliferative genes. Here, we show that the p53-related gene p73 is a target of tazarotene. Indeed, tazarotene modulates the expression of the p73 gene in immortalized keratinocyte cell lines by inducing the pro-apoptotic and anti-proliferative TAp73 isoforms and by repressing the anti-apoptotic and pro-proliferative DeltaNp73 isoforms. This occurs at the transcriptional level through a coordinated action on P1p73 and P2p73 promoters that control the expression of TA and DeltaN isoforms, respectively. The selective downregulation of DeltaNp73 expression by small interfering RNA led to an enhancement of tazarotene-induced bax activation and apoptosis, whereas the downregulation of both TA and DeltaN isoforms impairs tazarotene-mediated apoptosis. These results indicate the relevance of p73 gene products in tazarotene-induced growth inhibition and effectiveness in the treatment of skin tumors.

Disorders of keratinization: diagnosis and management

Disorders of cornification are a group of diseases that share abnormalities in the manufacture or desquamation of corneocytes. This paper reviews the major and a few of the rarer ones with a concentration on their therapy. Ichthyosis vulgaris is probably a post-translational defect in pro-filaggrin expression. It shows fine white flaky scales of the extensor surfaces, trunk, flank, lower legs but spares the folds and wet areas. Treatment is with aggressive moisturization. Hydrocortisone creams may be needed to control itch. Recessive X-linked ichthyosis is due to a deficiency of cholesterol sulfatase. Boys with this condition show small dark scales around the ears, sides of the neck, extensor surfaces of the arms and legs, and the peri-umbilical region. It spares the folds and face. Treatment is with moisturizers, topical retinoid creams or with topical cholesterol-based creams. Checking for signs of contiguous gene disorders (Kallman or Conradi-Hunermann syndromes) is necessary. Bullous congenital ichthyosiform erythroderma is caused by mutations in keratins 1 and/or 10. These patients are born as bright red babies with large blisters and erosions. Slowly, a porcupine quill-like waxy scaling develops. Blistering continues throughout life. Secondary infections of the skin cause pain, debility, and a very foul odor. Treatment is difficult. Topical moisturizers, descalers and retinoid creams help a little. Oral retinoids help a lot but can cause increased blistering. Controlling the odor is an ongoing issue using antibacterial washes, absorbing powders, and masking fragrances. Autosomal recessive ichthyosis is a term for both lamellar ichthyosis and congenital ishthysosiform erythroderma. They are caused by various mutations in transglutaminase-1 gene. In both instances patients are born as 'collodion babies'. Lamella ichthyosis has the very recognizable plate-like scale over the entire body. Children with congenital ishthysosiform erythroderma are red all over with a finer scale in some places and plate-like scales in others. Treatment is with topical moisturizers, retinoid creams, descalers, and in some cases oral retinoids. Palmar plantar keratodermas occur in conjunction with some ichthyoses, but also by themselves. Some are diffuse and others have discrete, corn-like hardenings. Treatment with topical acids, propylene glycol and retinoid creams help to some extent.Throughout the article pearls from my practice are included to assist the clinician in the day-to-day handling of these patients. A short section on genetic counseling concludes this article.

Treatment of lentigo maligna with tazarotene 0.1% gel

We report 2 elderly patients with facial lentigo maligna who experienced complete regression, both clinically and histopathologically, after once-daily topical treatment with tazarotene 0.1% gel for 6 to 8 months. After a follow-up period of 18 and 30 months, no recurrence was observed. We believe that tazarotene might be considered as an alternative medical approach in selected patients with lentigo maligna.

Type I lamellar ichthyosis improved by tazarotene 0.1% gel

The efficacy of tazarotene 0.1% gel in a 30-year-old woman with type I lamellar ichthyosis is reported. The drug was applied to 15% of the total body surface area as follows: once daily for 2 weeks, three times a week for further 2 weeks, followed by a once weekly maintenance application. During the first week of treatment there was partial improvement obtained and in the next 14 days further reduction of scaling within the tazarotene-treated areas was observed. After 4 months of maintenance application, there was a marked overall improvement in the treated areas. Side-effects consisted only of mild pruritus, slight burning and irritation. In essence, the therapeutic benefit obtained was comparable with that of systemic retinoids but without the adverse systemic side-effects. As noted in other reports, tazarotene 0.1% gel seems to be a valuable and safe therapeutic option for this severe genodermatosis.

Ichthyosis: etiology, diagnosis, and management

The ichthyoses are a heterogeneous group of disorders with both inherited and acquired forms. Clinical presentation, pattern of inheritance, and laboratory evaluation may establish a precise diagnosis, which can assist in prognosis and genetic counseling. Congenital autosomal recessive ichthyosis (CARI) usually presents at birth, often as a collodion baby. CARI can progress into any one of a spectrum of disorders. Lamellar ichthyosis is characterized by dark, plate (armor)-like scale. This disease is often caused by mutations in the gene encoding the enzyme transglutaminase 1. Congenital ichthyosiform erythroderma is another phenotype within CARI, marked by generalized redness and fine white scale. Epidermolytic hyperkeratosis is an autosomal dominant disorder characterized by hyperkeratosis and blistering, and at least six clinical phenotypes have been described. It may be due to mutations in the gene encoding the intermediate filament proteins keratin 1 and 10. Ichthyosis vulgaris is the most common ichthyosis, and is inherited in an autosomal dominant pattern. Involvement is generally mild and may vary greatly with climate and humidity. X-linked ichthyosis, due to a defect in the enzyme steroid sulfatase, affects males with generalized scaling that usually begins soon after birth. There may be associated corneal opacities that do not affect vision. Sjögren-Larsson syndrome is an autosomal recessive ichthyosis associated with progressive spastic paralysis and mental retardation. This condition is caused by mutations in the gene for fatty aldehyde dehydrogenase. Refsum's disease, due to accumulation of phytanic acid, results in ichthyosis and progressive neurologic dysfunction. The erythrokeratodermas are characterized by hyperkeratosis and localized erythema. Erythrokeratodermia variabilis is autosomal dominant and characterized by generalized or localized hyperkeratosis and migratory red patches. Mutations in the genes encoding the gap junction proteins, connexins, underlie this disorder. Netherton's syndrome is an autosomal recessive disorder characterized by ichthyosis, a hair shaft abnormality and atopy. The ichthyosis may present at birth with erythroderma or in some cases a collodion presentation. However, a frequent characteristic skin manifestation is ichthyosis linearis circumflexa. Netherton's syndrome has been found to be due to an abnormality in a serum protease inhibitor. Acquired ichthyosis can have a variety of underlying causes including neoplastic, infectious, drugs, endocrine, metabolic, autoimmune, malabsorptive states, and hereditary. Topical, and in more severe cases, systemic, therapy are useful in managing this array of disorders of cornification.

Novel therapies for psoriasis

The T cell-driven immunopathogenesis of psoriasis has been well recognized since cyclosporine first revolutionized the treatment of psoriasis 20 years ago. Almost all investigative and clinical research subsequently, has concentrated on elucidating the specifics of antigen presentation, T cell interaction and the production of specific cytokines. The role of the keratinocyte, previously thought to be the primary target cell in psoriasis pathogenesis, has been relegated to a secondary role and the mechanism of action of systemic methotrexate in psoriasis has been challenged, the primary role of the T lymphocyte is now well known. While psoriasis has traditionally been treated "ab initio" with topical medications (corticosteroids, vitamin D(3), and retinoid derivatives), either singly, in combination, or with ultraviolet B (UVB) or psoralens and ultraviolet A (PUVA) therapy, the role of systemic medications has assumed greater prominence. Thus, three systemic medications currently are approved worldwide for the treatment of moderate to severe forms of psoriasis, namely cyclosporine, methotrexate and acitretin. The first two are likely to give significant clearing (greater than 75%) in the majority of cases, whereas acitretin is significantly less effective as monotherapy, but may approach methotrexate and cyclosporine in efficacy, if combined with PUVA or UVB phototherapy. The main limitations of these three drugs remain organ toxicity, especially hepatic toxicity with methotrexate, hypertension and nephrotoxicity with cyclosporine, and teratogenicity and mucocutaneous toxicity with acitretin. Thus, the need for more specific systemic therapy, targeting the T lymphocyte. This has become the major area of clinical research interest over the past 5 years, with the promise of longer-term disease control (improved remissions) and less organ toxicities. Currently, there are over 15 of these "biologic" drugs in various stages of development and clinical trials, either by the subcutaneous, intramuscular or intravenous route. The three main variables are the rapidity of onset, percentages of improvement and remission rates. Without exception, these new systemic agents appear to be remarkably free of systemic organ toxicities (liver, renal, bone-marrow, etc.), with adverse effects being limited to mild flu-like symptoms with the anticipated increase in infections (e.g., herpes simplex) being either equal to placebo or only marginally increased. Not all these agents under evaluation give clinical responses equal to methotrexate or cyclosporine (75% or greater clearing in 75% of cases). In addition, response rates may be slower with some therapies versus others. However, the need for intermittent administration even by the injectable route, longer remissions, lack of systemic organ toxicities and the potential for safer usage in females of child-bearing age, make a compelling argument for widespread acceptance by both patients and the dermatological community. Other modalities under clinical evaluation include vitamin D and retinoid drugs, topically and systemically, with effects on nuclear receptors, as well as more specific wavelengths (308 to 311 nm) of UVB phototherapy with application for more localized forms of psoriasis. For the 2 to 3% of the worldwide population of patients with psoriasis the future has never looked brighter.

Papulosquamous disorders of the elderly

Several papulosquamous skin conditions occur in the elderly, including inherited and acquired ichthyoses, psoriasis, cutaneous lymphoma, and cutaneous connective tissue diseases. The clinical presentations can be quite helpful in diagnosing these conditions, and confirmatory histology and immunologic testing can often better define the specific entities. Treatment often involves identifying underlying systemic causes, as well as specific approaches based on the diagnosis and severity of clinical presentation.