Managing actinic keratoses with retinoids

[Skin tumours of the facial area]

Almost the complete spectrum of skin tumours can occur within the facial area, ranging from benign tumours of infancy to typical malignancies of old age. This spectrum is quiet heterogeneous and comprises every cell type within the skin as a possible origin for tumour growth. Among these are cells derived from the epidermis; adnexal structures; connective, fatty, and vascular tissue; muscle; nerves; melanocytes; and skin-infiltrating inflammatory cells. Due to this diversity, a correct assessment of the clinical findings compared with a histopathologic appraisal in cases of uncertainty is mandatory in order to recommend appropriate therapy. The present overview aims to summarise the basics of the most frequent and most important skin tumours occurring on the face.

Treatment options for premalignant and malignant cutaneous tumors

Whenever possible, surgical excision of skin cancers should be the gold standard of treatment. There are many considerations when choosing one treatment modality over another. These include the lesion's location, the surgeon's experience and comfort level, the patient's health status and their potential compliance, access to available technology, and economic considerations for the patient and the provider. Regardless of the type of therapy, all forms of treatment share the following goals: complete disease cure, preservation of normal tissue, preservation of function, and optimal cosmesis.

Skin Cancer After Transplantation: A Guide for the General Surgeon

The success of organ transplantation has been accompanied by serious concerns regarding the incidence and management of potentially catastrophic cutaneous carcinogenesis in transplant recipients. Delivery of the highest quality of care requires a concerted effort toward collaboration between multiple surgical and medical specialties. The purpose of this review is to provide the general surgeon with a practical, user-friendly guide to the important components of comprehensive dermatologic care for organ transplant recipients (OTRs) with references to more detailed sources of information.

Expression of RPE65, a putative receptor for plasma retinol-binding protein, in nonmelanocytic skin tumours

BACKGROUND

In a recent report we described RPE65, a protein originally characterized in retinal pigment epithelium, to be expressed in normal human epidermis. RPE65 is suspected to be involved in cellular uptake of retinol which is transported in the bloodstream complexed with plasma retinol-binding protein.

OBJECTIVES

To evaluate protein and mRNA expression of RPE65 in actinic keratosis (AK), squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) compared with normal skin.

METHODS

RPE65 mRNA expression in skin tumours relative to normal skin of the respective donor was studied by real-time polymerase chain reaction in AK (n = 15), invasive SCC (n = 30) and BCC (n = 18). A peptide-specific anti-RPE65 antibody was used for immunohistochemical staining of formalin-fixed and paraffin-embedded tissue sections of the respective tumours.

RESULTS

RPE65 mRNA expression was reduced in AK. A highly significant reduction of RPE65 mRNA was observed in invasive SCC relative to normal skin of the respective donors. Immunohistochemistry revealed a continuous staining of basal and suprabasal keratinocytes in normal human epidermis. RPE65 in AK shown by immunohistochemical staining was reduced and quite irregular, whereas invasive SCC revealed no staining of tumour cells with the anti-RPE65 antibody. RPE65 mRNA values were elevated, whereas immunohistochemical staining for RPE65 protein was heterogeneous in BCC.

CONCLUSIONS

These results suggest progressive downregulation of RPE65 from AK to invasive SCC.

Acitretin and skin cancer in kidney transplanted patients. Clinical and histological evaluation and immunohistochemical analysis of lymphocytes, natural killer cells and Langerhans' cells in sun exposed and sun protected skin

BACKGROUND

Renal transplanted recipients have an increased incidence of actinic keratosis and skin cancer.

METHODS

In order to examine the chemoprophylatic effects of low-dose acitretin on keratosis and skin cancer development we submitted 13 renal transplanted patients who presented actinic keratosis to acitretin therapy (20 mg/d) for 12 months. The patients were assessed at monthly intervals during the first 6 months and every 2 months until the 12th month for new skin lesions and for acitretin toxicity. Normal skin biopsies of sun exposed and sun protected areas were taken for histopathological examination and submitted to immunohistochemistry technique to demonstrate CD4+ and CD8+ T lymphocytes, natural killer (NK) cells and Langerhans' cells which were counted and compared before, after 6 and 12 months of the treatment.

RESULTS

There was an improvement of actinic keratosis in all patients. Only one patient developed new skin cancer. Side-effects were well tolerated and no significant biochemical effects were observed. There were no differences in the microscopic aspects of the skin and in the number of CD4+ and CD8+ T lymphocytes and NK cells. There was a significant increase in the number of epidermal Langerhans' cells after 12 months of acitretin therapy.

CONCLUSIONS

The data obtained permit us to conclude that low dose acitretin therapy is safe, well tolerated and partially effective in chemoprophylaxis of skin cancer in renal transplant recipients. The increase in epidermal Langerhans' cells observed may be an expression of the immunomodulatory effect of acitretin.

Premalignant and early squamous cell carcinoma

Actinic keratosis (AK) is a common sun-induced precancerous neoplasm confined to the epidermis. The AK is the initial manifestation of a continuum of clinical and histologic abnormalities that progresses to invasive squamous cell carcinoma (SCC). Bowen's disease, also known as squamous cell carcinoma in situ, represents early SCC confined to the epidermis. More than half of all SCCs contain p53 tumor suppressor gene mutations. Like SCCs, the vast majority of AKs and Bowen's disease lesions are asymptomatic. Each AK and suspicious lesion should be treated before it progresses to invasive SCC. Destructive modalities, such as cryosurgery using liquid nitrogen and electrodesiccation and curettage, usually performed by a dermatologist, are the mainstays of therapy.

Practical retinoid chemoprophylaxis in solid organ transplant recipients

Solid organ transplant recipients are at a significantly increased risk of developing skin cancer. Both systemic and topical retinoids are useful for chemosuppression of skin cancer in this patient population. These drugs can reduce both the present extent and the future development of premalignant and malignant skin lesions. This paper reviews the current data on the chemoprophylactic properties of topical and systemic retinoids. A practical guide for their use in organ transplant recipients is provided. Specific recommendations for implementing and maintaining therapy, as well as appropriate management and monitoring of adverse events, are presented.

Retinoids: fascinating up-and-coming scenario

Retinoids have been in sharp focus ever since their introduction 30 years ago. They include any drug (s) that bind to retinoid receptors and elicit a biological response. Enormous information on the subject seems to embroil the recent literature. Practically it is impossible to clearly comprehend the undercurrents. The meticulously dispensing text envisages surmounting the perspective reader's predicaments. Accordingly, retinoids and their related facets namely retinoid receptors, classification, mode of action, and the pharmacological diversity have been precisely defined. Commonly used systemic retinoids too have been given a substantial fresh look along with their monitoring. Overall, adverse effects and relative and absolute contraindications have been scrupulously incorporated. Human immuno deficiency virus (HIV) and isoretinoid for acne, in particular, have been highlighted. Micronized isotretinoin formulations have also been taken care so also commonly used topical retinoids. Tretinoin and their newer formulation have also been accounted for along with tretinoin polymer cream. Adapalene, a new chemical entity possessing a unique physico-chemical activity similar to that of tretinoin has also been dealt with. Newer retinoids are likely to be a subject of intrigue. A focus on future potentials of retinoids is its special ingredient. The inclusion of details of rexinoid the most recent introduction in their purview is likely to invoke interest to further consolidate its reckoning in future. All in all the text of the paper should provide an insight into the current rumbling around retinoids.

Skin cancer in organ transplant recipients: Epidemiology, pathogenesis, and management

In the United States more than 100,000 people are living with solid organ transplants. The intense immunosuppressive regimens necessary for prolonged survival of allografts significantly increase the rates of both internal and cutaneous malignancies in recipients of solid organ transplants. Skin cancer is the most common cancer in patients after transplantation. Because of the early onset and high tumor burden in transplant recipients, dermatologists have significant challenges in managing the treatment of these patients. This article describes the epidemiology and clinical presentation of skin cancer during posttransplantation immunosuppression, discusses pathogenic cofactors, and reviews the optimal management for mild and severe skin cancer in transplant recipients.

Nordihydroguaiaretic acid-mediated inhibition of ultraviolet B-induced activator protein-1 activation in human keratinocytes

Nordihydroguaiaretic acid (NDGA) is a polyphenolic compound from the Larrea tridentata bush that has been identified as a chemopreventive drug in animal studies. Topically applied NDGA has been shown to prevent phorbol ester promotion of tumors in mouse skin, suggesting that NDGA may be a candidate drug for the chemoprevention of skin cancer. Ultraviolet (UV) B irradiation from sunlight exposure is the major cause of human skin cancer. UVB irradiation causes epigenetic alterations in target keratinocytes, such as the upregulation of signal transduction pathways that induce the expression of transcription factors. Specifically, UVB induces activator protein-1 (AP-1), a transcription factor complex that alters normal cellular gene expression. A component of the UVB-induced AP-1 complex, c-fos, also was identified as a mediator of the signaling pathway that leads to AP-1 activation. Thus, NDGA was investigated as a potential inhibitory agent for UVB-induced signaling pathways in the human keratinocyte cell line HaCaT. NDGA significantly inhibited UVB-induced c-fos and AP-1 transactivation. In addition, NDGA was found to inhibit activity of phosphatidylinositol 3-kinase (PI 3-kinase), a UVB-inducible enzyme that contributes to the induced expression of c-fos and AP-1. Therefore, NDGA prevents UVB-induced c-fos expression and AP-1 transactivation by inhibiting the PI 3-kinase signaling pathway. Effective skin chemoprevention strategies may incorporate NDGA to inhibit components of the UVB-induced cell signaling pathways that increase AP-1 activity.

A pharmacokinetic evaluation of 0.5% and 5% fluorouracil topical cream in patients with actinic keratosis

BACKGROUND

Systemic absorption of topical fluorouracil, although usually low, may vary as a result of the specific skin disease, product formulation, and other factors.

OBJECTIVE

The present study was conducted to determine the pharmacokinetic profile and tolerability of a new topical 0.5% fluorouracil cream formulation compared with that of a currently available topical formulation of 5% fluorouracil cream.

METHODS

This was an open-label, parallel-group study in which patients with actinic keratosis (AK) were randomized to treatment with either topical 0.5% fluorouracil once daily or topical 5% fluorouracil twice daily for up to 28 days.

RESULTS

Twenty-one patients (all white; mean age, 64 years) participated in the study, 11 receiving topical 0.5% fluorouracil and 10 receiving topical 5% fluorouracil. Ten patients receiving 0.5% fluorouracil and 7 patients receiving 5% fluorouracil completed the 28-day study. Plasma concentrations of fluorouracil were detectable in 3 of 10 patients treated with 0.5% fluorouracil and 9 of 10 patients treated with 5% fluorouracil; fluorouracil was detected in the urine of 5 and 9 patients, respectively. Despite the one-tenth difference in drug concentration between formulations, the cumulative amount excreted in the urine of the 0.5% fluorouracil group was approximately one fortieth that of the 5% fluorouracil group. This difference may be a result of variations in vehicle formulations. At least 1 adverse event was reported by 4 of 11 patients in the 0.5% fluorouracil group and all 10 patients in the 5% fluorouracil group. The most common adverse event, facial irritation, was evident with both formulations but reached a plateau during treatment with 0.5% fluorouracil. All patients treated with 0.5% fluorouracil tolerated the full course of therapy, whereas 3 patients in the 5% fluorouracil group discontinued treatment early. No serious treatment-related adverse events were reported.

CONCLUSIONS

These data suggest that 0.5% fluorouracil has minimal systemic absorption and is well tolerated in patients with AK.