Topical treatment of multiple actinic keratoses of the face with arotinoid methyl sulfone (Ro 14-9706) cream versus tretinoin cream: a double-blind, comparative study

Actinic keratoses: review of clinical, dermoscopic, and therapeutic aspects

Actinic keratoses are dysplastic proliferations of keratinocytes with potential for malignant transformation. Clinically, actinic keratoses present as macules, papules, or hyperkeratotic plaques with an erythematous background that occur on photoexposed areas. At initial stages, they may be better identified by palpation rather than by visual inspection. They may also be pigmented and show variable degrees of infiltration; when multiple they then constitute the so-called field cancerization. Their prevalence ranges from 11% to 60% in Caucasian individuals above 40 years. Ultraviolet radiation is the main factor involved in pathogenesis, but individual factors also play a role in the predisposing to lesions appearance. Diagnosis of lesions is based on clinical and dermoscopic examination, but in some situations histopathological analysis may be necessary. The risk of transformation into squamous cell carcinoma is the major concern regarding actinic keratoses. Therapeutic modalities for actinic keratoses include topical medications, and ablative and surgical methods; the best treatment option should always be individualized according to the patient.

Actinic keratosis - review for clinical practice

Actinic keratosis (AK) is a lesion that arises as a result of excessive exposure to solar radiation and appearing predominantly on Fitzpatrick phototype I and II skin. Given that some AKs evolve into squamous cell carcinoma, these lesions are considered premalignant in nature, occurring mostly in elderly men and immunosuppressed individuals chronically exposed to ultraviolet (UV) radiation. There are several mechanisms for the formation of AKs; among them are oxidative stress, immunosuppression, inflammation, altered proliferation and dysregulation of cell growth, impaired apoptosis, mutagenesis, and human papillomavirus (HPV). Through the understanding of these mechanisms, several treatments have emerged. Among the options for AK treatment, the most commonly used include 5-fluorouracil (5-FU), cryotherapy, diclofenac, photodynamic therapy (PDT), imiquimod (IQ), retinoids, and ingenol mebutate (IM). There have been recent advances in the treatment options that have seen the emergent use of newer agents such as resiquimod, betulinic acid, piroxicam, and dobesilate. The combination between therapies has presented relevant results with intention to reduce duration of therapy and side effects. All AK cases must be treated because of their propensity to transform into malignancy and further complicate treatment. In addition to medical or surgical care, education about sun exposure prevention remains the best and most cost-effective method for AK prevention. The objective of this article is to conduct a literature review of the clinical presentation of AK including advances in treatment options available.

Neoplastic Multifocal Skin Lesions: Biology, Etiology, and Targeted Therapies for Nonmelanoma Skin Cancers

Neoplastic skin lesions are multifocal, diffuse skin infiltrations of particular relevance in the differential diagnosis of ulcerative, nodular, or crusting skin lesions. Nonmelanoma skin cancers (NMSCs), namely, basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and also actinic keratosis (AK), are the most common malignant tumors in humans. BCCs do not proliferate rapidly and most of the times do not metastasize, while SCCs are more infiltrative, metastatic, and destructive. AKs are precursor lesions of cutaneous SCCs. The classical therapy of NMSCs makes use of photodynamic therapy associated with chemotherapeutics. With improved understanding of the pathological mechanisms of tumor initiation, progression, and differentiation, a case is made towards the use of targeted chemotherapy with the intent to reduce the cytotoxicity of classical treatments. The present review aims to describe the current state of the art on the knowledge of NMSC, including its risks factors, oncogenes, and skin carcinogenesis, discussing the classical therapy against new therapeutic options.

A new, objective, quantitative scale for measuring local skin responses following topical actinic keratosis therapy with ingenol mebutate

Introduction

Local skin responses (LSRs) are the most common adverse effects of topical actinic keratosis (AK) therapy. There is currently no method available that allows objective characterization of LSRs. Here, the authors describe a new scale developed to quantitatively and objectively assess the six most common LSRs resulting from topical AK therapy with ingenol mebutate.

Methods

The LSR grading scale was developed using a 0–4 numerical rating, with clinical descriptors and representative photographic images for each rating. Good inter-observer grading concordance was demonstrated in peer review during development of the tool. Data on the use of the scale are described from four phase III double-blind studies of ingenol mebutate (n = 1,005).

Results

LSRs peaked on days 4 (face/scalp) or 8 (trunk/extremities), with mean maximum composite LSR scores of 9.1 and 6.8, respectively, and a rapid return toward baseline by day 15 in most cases. Mean composite LSR score at day 57 was generally lower than at baseline.

Conclusion

The LSR grading scale is an objective tool allowing practicing dermatologists to characterize and compare LSRs to existing and, potentially, future AK therapies.

Electronic supplementary material

The online version of this article (doi:10.1007/s13555-014-0059-9) contains supplementary material, which is available to authorized users.

Retinoids for prevention and treatment of actinic keratosis

Actinic keratosis is a common cause of dermatological consultations and it presents a strong association with squamous cell carcinoma. Many substances are used for treatment and prevention, such as retinoids. Nevertheless, many studies on retinoids emphasize their application in treating and preventing non melanoma skin cancers. In this article, we reviewed studies about systemic and topical retinoids used with immunocompetent patients and organ transplant recipients with actinic keratosis, as primary or secondary outcomes. The majority of these papers pointed to a reduction in actinic keratosis count after treatment with retinoids. However, studies need to be better-defined in order to address the lack of a standardized dose, the absence of control groups, the low number of patients and short follow-up periods. Blind, randomized and controlled clinical trials with adequate sample sizes, specifically focused on actinic keratosis, are needed to clarify the real benefit of topical and/or oral retinoids. Comparison of efficacy and safety between oral and topical retinoids in the prevention and treatment of non-melanoma skin cancers and actinic keratosis is an essential pre requisite to establish new strategies to control these conditions.

Pharmacotherapy of actinic keratosis: an update

INTRODUCTION

Actinic keratosis (AK) represents the initial intraepidermal manifestation of abnormal keratinocyte proliferation, with the potential of progression to squamous cell carcinoma (SCC). Few visible AKs lead to the use of lesion-directed treatments, including ablative and/or surgical procedures. Multiple and/or the suspicion of subclinical (non-visible) AKs lead to the use of field-directed therapies, including topical and ablative treatments. Predicting which AK will progress to SCC is difficult, and so all are treated. The goals of treatment are to eliminate visible AKs and to treat subclinical (non-visible) AKs, minimizing their risk of progression to invasive SCC, while pursuing good cosmesis.

AREAS COVERED

This review discusses the prevention of AKs (such as ultraviolet light avoidance, sunscreen use, protective clothing, and frequent self-examinations, in addition to chemoprevention with retinoids, eflornithine, silymarin, and others). It also covers lesion-directed treatments (e.g., cryotherapy, electrodessication and curettage, and surgery). Field-directed treatments are also mentioned (including laser resurfacing, dermabrasion, chemical peels, topical immunomodulators (imiquimod and diclofenac), topical chemotherapeutic agents (5-fluorouracil and retinoids), and photodynamic therapy). Finally, newer and investigational treatments are discussed (including ingenol mebutate).

EXPERT OPINION

There is no panacea in the treatment of AKs. The current best approach is the sequential treatment with a lesion-directed and a field-directed therapy. Several combinations seem to work well; they just need to be selected based on the evidence and adjusted to patient needs, preferences and dermatologist expertise.

Interventions for actinic keratoses

BACKGROUND

Actinic keratoses are a skin disease caused by long-term sun exposure, and their lesions have the potential to develop into squamous cell carcinoma. Treatments for actinic keratoses are sought for cosmetic reasons, for the relief of associated symptoms, or for the prevention of skin cancer development. Detectable lesions are often associated with alteration of the surrounding skin (field) where subclinical lesions might be present. The interventions available for the treatment of actinic keratoses include individual lesion-based (e.g. cryotherapy) or field-directed (e.g. topical) treatments. These might vary in terms of efficacy, safety, and cosmetic outcomes.

OBJECTIVES

To assess the effects of topical, oral, mechanical, and chemical interventions for actinic keratosis.

SEARCH METHODS

We searched the following databases up to March 2011: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library, MEDLINE (from 2005), EMBASE (from 2010), and LILACS (from 1982). We also searched trials registers, conference proceedings, and grey literature sources.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing the treatment of actinic keratoses with either placebo, vehicle, or another active therapy.

DATA COLLECTION AND ANALYSIS

At least two authors independently abstracted data, which included adverse events, and assessed the quality of evidence. We performed meta-analysis to calculate a weighted treatment effect across trials, and we expressed the results as risk ratios (RR) and 95% confidence intervals (CI) for dichotomous outcomes (e.g. participant complete clearance rates), and mean difference (MD) and 95% CI for continuous outcomes (e.g. mean reduction in lesion counts).

MAIN RESULTS

We included 83 RCTs in this review, with a total of 10,036 participants. The RCTs covered 18 topical treatments, 1 oral treatment, 2 mechanical interventions, and 3 chemical interventions, including photodynamic therapy (PDT). Most of the studies lacked descriptions of some methodological details, such as the generation of the randomisation sequence or allocation concealment, and half of the studies had a high risk of reporting bias. Study comparison was difficult because of the multiple parameters used to report efficacy and safety outcomes, as well as statistical limitations. We found no data on the possible reduction of squamous cell carcinoma.The primary outcome 'participant complete clearance' significantly favoured four field-directed treatments compared to vehicle or placebo: 3% diclofenac in 2.5% hyaluronic acid (RR 2.46, 95% CI 1.66 to 3.66; 3 studies with 420 participants), 0.5% 5-fluorouracil (RR 8.86, 95% CI: 3.67 to 21.44; 3 studies with 522 participants), 5% imiquimod (RR 7.70, 95% CI 4.63 to 12.79; 9 studies with1871 participants), and 0.025% to 0.05% ingenol mebutate (RR 4.50, 95% CI 2.61 to 7.74; 2 studies with 456 participants).It also significantly favoured the treatment of individual lesions with photodynamic therapy (PDT) compared to placebo-PDT with the following photosensitisers: aminolevulinic acid (ALA) (blue light: RR 6.22, 95% CI 2.88 to 13.43; 1 study with 243 participants, aminolevulinic acid (ALA) (red light: RR 5.94, 95% CI 3.35 to 10.54; 3 studies with 422 participants), and methyl aminolevulinate (MAL) (red light: RR 4.46, 95% CI 3.17 to 6.28; 5 studies with 482 participants). ALA-PDT was also significantly favoured compared to cryotherapy (RR 1.31, 95% CI 1.05 to 1.64).The corresponding comparative risks in terms of number of participants completely cleared per 1000 were as follows: 313 with 3% diclofenac compared to 127 with 2.5% hyaluronic acid; 136 with 0.5% 5-fluorouracil compared to 15 with placebo; 371 with 5% imiquimod compared to 48 with placebo; 331 with ingenol mebutate compared to 73 with vehicle; 527 to 656 with ALA/MAL-PDT treatment compared to 89 to 147 for placebo-PDT; and 580 with ALA-PDT compared to 443 with cryotherapy.5% 5-fluorouracil efficacy was not compared to placebo, but it was comparable to 5% imiquimod (RR 1.85, 95% Cl 0.41 to 8.33).A significant number of participants withdrew because of adverse events with 144 participants affected out of 1000 taking 3% diclofenac in 2.5% hyaluronic acid, compared to 40 participants affected out of 1000 taking 2.5% hyaluronic acid alone, and 56 participants affected out of 1000 taking 5% imiquimod compared to 21 participants affected out of 1000 taking placebo.Based on investigator and participant evaluation, imiquimod treatment and photodynamic therapy resulted in better cosmetic outcomes than cryotherapy and 5-fluorouracil.

AUTHORS' CONCLUSIONS

For individual lesions, photodynamic therapy appears more effective and has a better cosmetic outcome than cryotherapy. For field-directed treatments, diclofenac, 5-fluorouracil, imiquimod, and ingenol mebutate had similar efficacy, but their associated adverse events and cosmetic outcomes are different. More direct comparisons between these treatments are needed to determine the best therapeutic approach.

Tolerability of high-dose topical tretinoin: the Veterans Affairs Topical Tretinoin Chemoprevention Trial

BACKGROUND

Topical tretinoin is a medication commonly used for acne that has potential application in the long-term treatment of photodamaged skin. However, there are few published data regarding the tolerability of high-dose tretinoin with long-term use.

OBJECTIVES

To assess the long-term tolerability of tretinoin 0.1% cream.

METHODS

A randomized, multicentre, double-blind, controlled trial for chemoprevention of keratinocyte carcinomas (i.e. basal cell or squamous cell carcinomas) using topical tretinoin cream to the face and ears was conducted. All participants were veterans and had a history of two or more keratinocyte carcinomas over the previous 5 years. Participants were examined (by a study dermatologist) and interviewed every 6 months (for up to 5.5 years to May 2004). Treatment comprised tretinoin 0.1% cream or vehicle control cream once daily, then twice daily as tolerated. Participants were instructed to step down application frequency to once daily or less if twice daily was not tolerated. The main outcome measures were reported side-effects, frequency of cream application and attendance at study visits. Appropriate data were available for four of the six clinical sites of this trial.

RESULTS

Data from 736 randomized participants (mean age 71 years; 97% men) from four clinical sites were analysed. The tretinoin group more commonly reported one or more side-effects at the 6-month follow-up than the control group (61% vs. 42%, P < 0.0001). Side-effects decreased over time in both groups, but to a greater extent in the tretinoin group, and the difference became nonsignificant at 30 months. Burning was the most common side-effect (39% tretinoin vs. 17% control, P < 0.0001). There was no difference in severity of side-effects among those affected. Of the participants who reported burning in either group, most reported mild burning; only 11% of those with burning in the tretinoin group reported it as severe (mild 62% tretinoin vs. 70% placebo; severe 11% vs. 5%; P = 0.4). Itching (24% vs. 16%, P = 0.01) and other local cutaneous reactions (12% vs. 6%, P = 0.01) were also more commonly reported by the tretinoin group at 6 months. There was no difference in numbness (2% vs. 2%, P = 0.9). Participants in the tretinoin group were less likely to apply cream twice daily at 6 months (29% vs. 43%, P = 0.0002). This difference persisted over the entire duration of follow-up. There was little difference between groups in attendance at study visits or completion of telephone interviews (92% vs. 95%, P = 0.06). No unexpected adverse events were reported.

CONCLUSIONS

Overall, the tolerability level of topical tretinoin was high in this study population, with almost 40% of the tretinoin group reporting no side-effects, and the majority (67%) tolerating at least once-daily dosing at 6-month follow-up. High-dose topical tretinoin is feasible for long-term use in this population.

Guidelines for the management of actinic keratoses

These guidelines stemmed from a consensus meeting held by the British Photobiology Group (BPG) in 1999. Following this meeting one of the authors (J.M.M.) was invited to draw up guidelines for the management of actinic keratoses by the British Association of Dermatologists Therapy Guidelines and Audit Subcommittee. Relevant evidence was sought using the search terms 'solar keratosis' and 'actinic keratosis' in Medline from 1966 onwards. Additional and earlier literature was reviewed on the basis of references within post-1966 publications. All articles of apparent relevance were reviewed independently of the nature of the publication. The quality of the evidence elicited has been indicated. The National Ambulatory Medical Care Survey (U.S.A.) was used for further data on topical chemotherapy. Papers were reviewed and discussed by the contributors to the BPG Workshop (see Acknowledgments). Recommendations are evidence based where possible. Strength of recommendation is coupled with quality of evidence. Strength of recommendation includes consideration of apparent cost-benefit and practical considerations. Quality of evidence reflects the nature of the trial structure that provides data of efficacy.

Retinoids in cosmeceuticals

Retinoids are natural and synthetic vitamin A derivatives. They are lipophilic molecules and easily penetrate the epidermis. Their biologically active forms can modulate the expression of genes involved in cellular differentiation and proliferation. Retinoic acid (tretinoin), its 13-cis isomer isotretinoin, as well as various synthetic retinoids are used for therapeutic purposes, whereas retinaldehyde, retinol, and retinyl esters, because of their controlled conversion to retinoic acid or their direct receptor-independent biologic action, can be used as cosmeceuticals. These natural retinoic acid precursors are thus expected to be helpful in (i) renewing epidermal cells, (ii) acting as UV filters, (iii) preventing oxidative stress, (iv) controlling cutaneous bacterial flora, and (v) improving skin aging and photoaging. Retinol and retinyl esters are not irritant, whereas demonstrating only a modest clinical efficiency. On the other hand, retinaldehyde, which is fairly well tolerated, seems to be the most efficient cosmeceutical retinoid; it has significant efficiency toward oxidative stress, cutaneous bacterial flora, epidermis renewing, and photoaging.

Chemoprevention of human skin cancer

The incidence of skin cancer has been rising in recent years with significant effects on public health. Primary prevention has proven inadequate in impacting the incidence of skin cancer, thus stimulating the development of chemopreventive strategies. The majority of skin cancer chemoprevention studies focus on occurrence of new nonmelanoma skin cancers (NMSC) in individuals with a previous NMSC, or on reduction in the number of premalignant skin lesions such as actinic keratoses (AK). Dysplastic nevi, a likely precursor of melanoma, are also potential targets for chemoprevention strategies. Premalignant lesions are especially attractive as endpoints since they are more common than frank cancer, resulting in reduced sample size, length, and cost of clinical trials. Development of new agents that affect the pathogenesis of skin cancer will be discussed, from elucidation of molecular targets to implementation of trials designed to determine the effects of chemopreventive interventions on human skin cancer.

The use of retinoids in the prevention and treatment of skin cancer

There has been a significant increase in the number of cases of skin cancer diagnosed in the US in the past few years. Thus, it seems appropriate to review the available compounds that might be used in the chemoprevention of these lesions. This review focuses on the retinoids and details their results in clinical trials for treatment and prevention of skin cancer. Side effects of the various retinoid derivatives are also discussed. It is concluded that isotretinoin (13-cis-retinoic acid) is the most effective retinoid for the prevention of non-melanoma skin cancers in high-risk patients in clinical trials. Current basic research is focused on developing receptor-selective retinoids which would have a higher therapeutic index for the treatment and chemoprevention of skin cancer.

Topical delta-aminolevulinic acid-based photodynamic therapy for Japanese actinic keratoses

Based on the opinion that 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) may be disadvantageous to Oriental patients with dark skin, including Japanese, because the competing chromophore melanin inhibits the photochemical reaction, we assessed the therapeutic effects when Japanese AK were treated with ALA-PDT. Fifty-three lesions in ten patients were followed up for over one year. The cure rates of AK on the face including the neck and on extremities were 81.8% and 55.6%, respectively. The results were approximately the same cure rates as those reported for AK in Caucasian patients. However, a larger number of treatment sessions were required. In the red light range, incoherent light including 630 nm and 670 nm is superior to 630 nm laser light.

Does intermittent "pulse" topical 5-fluorouracil therapy allow destruction of actinic keratoses without significant inflammation?

BACKGROUND

Topical 5-fluorouracil (5-FU) is effective in removing actinic keratoses but causes unsightly and painful erosions. Intermittent "pulse" 5-FU therapy has been described as being an effective and comfortable technique for destroying actinic keratoses.

OBJECTIVE

The purpose of this study was to determine the efficacy and cutaneous side effects of intermittent 5-FU therapy.

METHODS

Efficacy of treatment was evaluated by three experienced dermatologists separately comparing randomly arranged before and after photographs. Degree of skin reaction was graded from photographs taken during treatment.

RESULTS

Of 13 patients treated with intermittent 5-FU, two had an excellent result, three a good result, but eight failed to show discernible improvement. Efficacy was linked to the degree of skin irritation.

CONCLUSION

Pulse 5-FU failed to clear actinic keratoses in most patients. Intermittent 5-FU treatment does not dissociate its therapeutic efficacy from its undesirable erosive effects. Pulse therapy is a less intensive way of employing 5-FU and may be of value in patients unwilling to accept the erosions and discomfort that accompany the traditional course of daily 5-FU applications.

The actinic keratosis. A perspective and update

BACKGROUND

Actinic keratosis (AK) is a common sun-induced precancerous neoplasm confined to the epidermis. It is the initial manifestation of a continuum of clinical and histologic abnormalities that progresses to invasive squamous cell carcinoma (SCC), a disorder that accounts for thousands of preventable deaths in America each year.

OBJECTIVE

The purpose of this work is to describe the actinic keratosis.

METHODS

This effort was performed by a literature review and analysis.

RESULTS

Like SCCs, the vast majority of AKs are asymptomatic. Although some actinic keratoses may become clinically inapparent, possibly either due to immune rejection or simply having their external surface unknowingly scraped off, an untreated AK represents a potentially curable fatal cancer.

CONCLUSIONS

Each AK should be treated before it progresses to invasive squamous cell carcinoma. Destructive modalities such as cryosurgery using liquid nitrogen and electrodesiccation and curettage are the mainstays of therapy. Each case must be individualized.

LEARNING OBJECTIVES

After studying this article, participant should be able to: 1. Understand the concept of an actinic keratosis. 2. Learn how to recognize its clinical manifestations. 3. Be aware of the danger it poses as an easily curable papulonodule that may become a fatal cancer.

Topical treatment of the aging face

This article discusses the various over-the-counter and prescription products available to help improve sun-damaged skin, as well as superficial peeling agents. Practical suggestions for treating patients are given.

Resurfacing with topical agents

Evaluation of the aging face reveals many changes such as lentigines, coarseness, senile purpura, and fine lines that can be blamed primarily on photoaging. There are many topical preparations that are now being used or are under investigation for facial rejuvenation. These include retinold creams, alpha-hydroxy acids, Ethocyn (Chantal Skin Care Corp, Los Angeles, CA), topical vitamins, and topical hormonal treatments. There has been substantial media attention devoted to these "antiaging" cures but there is a lack of scientific evidence to support some of these claims. After review of these agents, a practical approach to the patient requesting younger-looking skin is presented.

Retinoids and the skin

Retinoids are a group of naturally occurring and synthetic compounds with vitamin A-like biological activity. They play an important role in vision, reproduction, growth, and epithelial cell differentiation. Recent discoveries of specific retinoid cellular binding proteins and nuclear receptors have led to a better (although not complete) understanding of the complex mechanisms of retinoid action. Numerous clinical studies have demonstrated beneficial effects of retinoids on skin diseases such as acne, psoriasis, ichthyoses, keratodermas, skin cancers and their precursors, as well as a reversal of the effects of photoaging.

Clinical evaluation of topical isotretinoin in the treatment of actinic keratoses

BACKGROUND

Retinoids have been shown to improve the manifestations of skin photodamage, including actinic keratoses.

OBJECTIVE

The efficacy and tolerability of isotretinoin 0.1% cream in the treatment of actinic keratoses were evaluated in a randomized, double-blind, placebo-controlled, parallel-group study.

METHODS

One hundred patients were randomly assigned to treatment with 0.1% cream or vehicle twice daily for 24 weeks to the face, the scalp, and the upper extremities. Patients were assessed every 4 weeks by the investigators, who counted and recorded the number of lesions in each treatment area. The 93 patients who had at least one postbaseline assessment were included for efficacy analysis. Local tolerability was evaluated at each study visit.

RESULTS

On the face, the reduction in number of actinic keratoses (mean +/- SEM) at the end of treatment was greater for patients treated with isotretinoin (3.9 +/- 0.6, i.e., 66% of patients with a reduction > 30%) than with placebo (1.7 +/- 0.5, i.e., 45% of patients with a reduction > 30%); this difference was statistically significant (p = 0.001). No significant drug effect was seen for lesions on the scalp or upper extremities. Mild to moderate local reactions with isotretinoin abated with reduced treatment frequency.

CONCLUSION

Our results suggest that isotretinoin 0.1% cream cannot compete with more rapid treatments of actinic keratoses. However, its effect on facial lesions may be beneficial during long-term treatment of associated sun-damaged skin.

An approach to the treatment of moderate to severe psoriasis with rotational therapy

BACKGROUND

There are four standard approaches for treating moderate to severe psoriasis: UVB plus tar, PUVA, methotrexate, and etretinate. Although patients with psoriasis receive these therapies for many years, there is no commonly accepted approach for the initial and subsequent selection of the alternatives.

OBJECTIVE

Our purpose was to develop a theoretical and practical basis for using these treatments that will minimize the risks of their long-term toxicities and prolong their safe long-term use.

METHODS

A review of the published side effects of the treatments and cumulative clinical experience are used to develop an approach for the treatment of severe psoriasis.

RESULTS

It is proposed that patients receive each form of therapy for 1 to 2 years and then switch to the next form of treatment. By rotating each of the three or four treatments at these time intervals, it may well be 4 or 5 years before needing to return to the first therapy, thereby minimizing cumulative toxicity by long periods off each treatment.

CONCLUSION

Rotation of available therapies for moderate to severe psoriasis may minimize long-term toxicity and allow effective treatments to be maintained for many years.

Retinoid therapy for aging skin and acne

Primary care physicians should be familiar with the effects and appropriate uses of retinoids. Topical tretinoin (Retin-A) can reverse photoaging of the skin, although some transient, undesirable side effects usually occur. In patients with acne vulgaris, topical tretinoin and systemic isotretinoin (Accutane) are the only agents that act upon the apparent underlying causes. Recurrence is unlikely after successful results are achieved. Chronic hypervitaminosis A presents insidiously, and physicians must maintain a high index of suspicion. Complete history taking should always include questions about the patient's use of vitamin supplements.

Current dermatologic therapy

This article reviews therapeutic advances reported in the English-language literature during 1991. Readers should review the original article in full before attempting any experimental or controversial therapy.

The effect of topical retinoids on the leukotriene-B4-induced migration of polymorphonuclear leukocytes into human skin

Systemic retinoids are effective in a variety of inflammatory dermatoses. Disorders in which polymorphonuclear leukocytes (PMN) are involved, such as psoriasis and acne, respond particularly well to various retinoids. However, side-effects restrict the use of systemic retinoids to severe manifestations. Topical application might provide the possibility of avoiding the systemic side-effects of these compounds. In this communication we report on the modulation of transepidermal migration of PMN by topical application of all-trans-retinoic acid, 13-cis-retinoic acid, arotinoid methyl sulphone and arotinoid ethyl sulphone. Test areas of healthy volunteers were pretreated with these retinoids in a cream base and with corresponding placebo creams, and intraepidermal accumulation of PMN was quantified 24 h after epicutaneous challenge with leukotriene B4 (LTB4), using elastase as a marker enzyme. Topical treatment with 13-cis-retinoic acid resulted in a marked and statistically significant inhibition of the LTB4-induced migration of PMN. All-trans-retinoic acid, arotinoid methyl sulphone and arotinoid ethyl sulphone reduced the accumulation of PMN slightly, but not statistically significantly. Topical treatment with arotinoid methyl sulphone had no effect.