Consensus recommendations for the treatment of basal cell carcinomas in Gorlin syndrome with topical methylaminolaevulinate-photodynamic therapy

An Institutional Experience of a Tertiary Referral Center in Surgically Managing Patients With Gorlin Syndrome

BACKGROUND

The lifetime risk for basal carcinoma (BCC) is 90% in patients with Gorlin syndrome, also known as basal cell nevus syndrome. Compared with non-Gorlin patients, Gorlin patients often develop BCCs at a younger age and in greater numbers up to 500 BCCs in a lifetime.

OBJECTIVE

To review the options available for Gorlin patients and highlight existing knowledge gaps where future studies are indicated to optimize the care of this unique population.

METHODS

We review the current literature on managing patients with Gorlin syndrome from the lens of a dermatologic surgeon.

RESULTS

Although Mohs surgery is still the gold standard for large and aggressive BCCs, other less-invasive approaches may be considered for smaller, more numerous lesions. As dermatologic surgeons, we must be open to the full spectrum of surgical and nonsurgical options to individualize treatment and optimize patients' quality of life. Without maintaining a balance between optimal cure rate and volume management, Gorlin patients become at risk for surgical burn out and loss to follow-up.

CONCLUSION

Gorlin patients undergo numerous surgeries especially on the central face which can lead to disfigurement and reduce the quality of life. Identifying gaps in the current literature, continuing ongoing research, and eventually establishing appropriate guidelines that help to guide the formation of an individualized treatment plan is crucial in developing a balance between conservative and complex treatments for this population.

Recommendations for Cost-Conscious Treatment of Basal Cell Carcinoma

BACKGROUND

Basal cell carcinoma (BCC) affects 3.3 million Americans annually. Treatment modalities for BCC include many surgical and nonsurgical options. The cost of BCC treatment can pose a substantial burden to patients and the healthcare system. Cost can be an important consideration in BCC treatment planning.

OBJECTIVE

We present an approach to the management of BCC when cost reduction is a priority.

METHODS

A PubMed literature search identified studies on effectiveness of current BCC therapies. Treatment prices were obtained from the Medicare National Fee Schedule, GoodRx, and pharmaceutical companies. The American Academy of Dermatology's (AAD) guidelines for treating BCC were used to develop recommendations for cost-reductive treatment.

RESULTS

The cost of treating a primary superficial BCC < 0.5 cm arising on Area M (cheeks, forehead, scalp, neck, jawline, pretibial surface) was $143 with curettage and electrodesiccation (C&E), $143 with cryosurgery, $210 with standard excision and simple reconstruction (SE), $1221 with Mohs Micrographic Surgery (MMS) and simple reconstruction, $472 with imiquimod, $186 with 5-fluorouracil (5-FU), and $354-$371 for photodynamic therapy (PDT). The cost of treating a primary nodular BCC 1.1-2 cm arising on Area L (trunk and extremities, excluding pretibial surface, hands, feet, nail units and ankles) was $183 with C&E, $183 with cryosurgery, $251 with SE and simple reconstruction, $1163-1351 with MMS and simple reconstruction, $472 with imiquimod, $186 with 5-FU, and $354-$371 for photodynamic therapy (PDT). The cost of treating a giant BCC (BCC > 10 cm with aggressive behavior) was $465-3311 with radiation, $139,560 with vismodegib, $144,452 with sonidegib, ~ $44.5 with cisplatin (medication cost only), and at least $184,836 with cemiplimab-rwlc.

CONCLUSIONS

For a primary superficial BCC < 0.5 cm arising on Area M, the cost-conscious algorithm prioritizes C&E or cryosurgery. For a primary nodular BCC 1.1-2 cm arising on Area L, the cost-conscious algorithm prioritizes C&E, cryosurgery, or 5-FU. For a giant BCC, the cost-conscious algorithm identifies superficial radiation therapy as first line.

Nonsurgical treatment options for basal cell carcinoma

ABSTRACT

Basal cell carcinoma (BCC) is the most common form of nonmelanoma skin cancer. Surgery, including Mohs micrographic surgery, is considered the gold standard for the management of BCC, yet some patients may be unable to undergo surgery. This article describes effective nonsurgical options for treating superficial BCCs as well as some nodular and infiltrative BCCs.

Tumor microenvironment in non-melanoma skin cancer resistance to photodynamic therapy

Non-melanoma skin cancer has recently seen an increase in prevalence, and it is estimated that this grow will continue in the coming years. In this sense, the importance of therapy effectiveness has increased, especially photodynamic therapy. Photodynamic therapy has attracted much attention as a minimally invasive, selective and repeatable approach for skin cancer treatment and prevention. Although its high efficiency, this strategy has also faced problems related to tumor resistance, where the tumor microenvironment has gained a well-deserved role in recent years. Tumor microenvironment denotes a wide variety of elements, such as cancer-associated fibroblasts, immune cells, endothelial cells or the extracellular matrix, where their interaction and the secretion of a wide diversity of cytokines. Therefore, the need of designing new strategies targeting elements of the tumor microenvironment to overcome the observed resistance has become evident. To this end, in this review we focus on the role of cancer-associated fibroblasts and tumor-associated macrophages in the resistance to photodynamic therapy. We are also exploring new approaches consisting in the combination of new and old drugs targeting these cells with photodynamic therapy to enhance treatment outcomes of non-melanoma skin cancer.

Modulation of Hedgehog Signaling for the Treatment of Basal Cell Carcinoma and the Development of Preclinical Models

Basal Cell Carcinoma (BCC) is the most commonly diagnosed cancer worldwide. While the survivability of BCC is high, many patients are excluded from clinically available treatments due to health risks or personal choice. Further, patients with advanced or metastatic disease have severely limited treatment options. The dysregulation of the Hedgehog (Hh) signaling cascade drives onset and progression of BCC. As such, the modulation of this pathway has driven advancements in BCC research. In this review, we focus firstly on inhibitors that target the Hh pathway as chemotherapeutics against BCC. Two therapies targeting Hh signaling have been made clinically available for BCC patients, but these treatments suffer from limited initial efficacy and a high rate of chemoresistant tumor recurrence. Herein, we describe more recent developments of chemical scaffolds that have been designed to hopefully improve upon the available therapeutics. We secondly discuss the history and recent efforts involving modulation of the Hh genome as a method of producing in vivo models of BCC for preclinical research. While there are many advancements left to be made towards improving patient outcomes with BCC, it is clear that targeting the Hh pathway will remain at the forefront of research efforts in designing more effective chemotherapeutics as well as relevant preclinical models.

Photodynamic therapy in pediatric age: Current applications and future trends

Photodynamic therapy (PDT) is a photochemotherapy based on local application of a photosensitive compound and subsequent exposure to a light source of adequate wavelength. It is a non-invasive therapeutic procedure widely used in oncodermatology for treatment of numerous skin cancers, but in the last years its use has been gradually extended to an increasing list of skin diseases of both infectious and inflammatory nature. Although PDT is proven as a safe and effective therapeutic option in adults, its use is not well standardized in the pediatric population. In this review, we will focus on clinical applications, mechanisms of action, protocols, and adverse events in children and adolescents. Most of pediatric experiences concerned treatment of skin cancers in Gorlin syndrome and xeroderma pigmentosum, acne vulgaris, and viral warts, but other applications emerged, such as cutaneous lymphoma and pseudo-lymphomas, necrobiosis lipoidica, hidradenitis suppurativa, dissecting cellulitis, leishmaniasis, angiofibromas, verrucous epidermal nevus, and linear porokeratosis. In these pediatric diseases, PDT appeared as an effective therapeutic alternative. The results on vitiligo were limited and not fully encouraging. Although highly versatile, PDT is not a therapy for all skin diseases, and a deeper knowledge of its mechanisms of action is required to better define its spectrum of action and safety in pediatric patients.

Advances in Management and Therapeutics of Cutaneous Basal Cell Carcinoma

Simple Summary

Basal cell carcinoma (BCC) is the most common malignancy in humans with a range of treatment options available. Tumor and patient characteristics aid in risk-stratification, which influences treatment considerations. Here, we review the advancements in surgical, topical, field, immunotherapeutic, molecular-targeted, and experimental treatment modalities that can be employed in the correct clinical setting for the treatment of BCC.

Abstract

Basal cell carcinoma (BCC), the most common cancer in humans, is a malignant neoplasm of cells derived from the basal layer of the epidermis. Tumor characteristics such as histologic subtype, primary versus recurrent tumor, anatomic location, size, and patient attributes determine the risk level and acceptable treatment options. Surgical options offer histologic confirmation of tumor clearance. Standard excision provides post-treatment histologic assessment, while Mohs micrographic surgery (MMS) provides complete margin assessment intraoperatively. Additional treatment options may be employed in the correct clinical context. Small and low-risk BCCs, broad field cancerization, locally-advanced disease, metastatic disease, cosmetic concerns, or morbidity with surgical approaches raise consideration of other treatment modalities. We review herein a range of treatment approaches and advances in treatments for BCC, including standard excision, MMS, electrodesiccation and curettage, ablative laser treatment, radiation therapy, targeted molecular therapies, topical therapies, field therapies, immunotherapy, and experimental therapies.

Nevoid basal cell carcinoma syndrome: a case report and literature review

BACKGROUND

Nevoid basal cell carcinoma syndrome (NBCCS) is a rare genetic disorder associated with basal cell carcinomas (BCC), skeletal anomalies, and jaw cysts, and a number of ocular abnormalities. We describe a case of a 12-year-old boy diagnosed with NBCCS found to have several ophthalmic manifestations including a myelinated retinal nerve fiber. We conducted a literature review targeting the ocular and systemic manifestations of NBCCS, with a focus on the ophthalmic findings that have not been well characterized.

MATERIALS AND METHODS

We conducted a literature search from 1960 to 2021 utilizing specific keywords and criteria and excluded non-clinical articles. A total of 46 articles were ultimately used for the literature review.

RESULTS

In NBCCS, BCCs typically present before the age of 30 and gradually become numerous. Certain ocular features, less common in the general population, are much more common with NBCCS. Depending on the study, prevalence of these features in patients with NBCCS ranges from 26-80% for hypertelorism and 7-36% for myelinated retinal nerve fiber layer. Prevalence of nystagmus in patients with NBCCS was found to be approximately 6%. Systemic findings such as bilamellar calcification of the falx cerebri, palmar pits, and odontogenic keratocysts (OKCs) are also prevalent.

CONCLUSION

NBCCS may affect numerous organ systems, and thus requires a multidisciplinary team to manage. BCCs and jaw cysts are commonly occurring clinical features that have various surgical excisional options. The ocular anomalies of NBCCS are individually rare, and certain anomalies may present in the amblyogenic period of development and contribute to visual impairment.

Basal cell nevus syndrome: an update on clinical findings

Basal cell nevus syndrome, also known as Gorlin-Goltz syndrome, is a rare autosomal dominant disorder caused by mutations in the hedgehog signaling pathway, mainly in PTCH1. This pathway is involved in embryogenesis and tumorigenesis, and the loss of function of PTCH1 protein produces an aberrant increase in the hedgehog signaling pathway activity. Basal cell nevus syndrome is characterized by tumor predisposition, particularly with the development of multiple basal cell carcinomas at an early age, along with odontogenic keratocysts, palmoplantar pits, skeletal abnormalities, and an increased risk of medulloblastoma. Diagnosis is clinical, with gene mutation analysis confirming the suspicion. The striking phenotypic variability of the syndrome may lead to a delayed diagnosis, making it an uncommon but important entity to recognize. A high index of suspicion and an early diagnosis is crucial for prevention, surveillance, and the prompt establishment of multidisciplinary medical care.

Photodynamic Therapy for Basal Cell Carcinoma: The Clinical Context for Future Research Priorities

Photodynamic therapy (PDT) is an established treatment option for low-risk basal cell carcinoma (BCC). BCC is the most common human cancer and also a convenient cancer in which to study PDT treatment. This review clarifies challenges to researchers evident from the clinical use of PDT in BCC treatment. It outlines the context of PDT and how PDT treatments for BCC have been developed hitherto. The sections examine the development of systemic and subsequently topical photosensitizers, light delivery regimens, and the use of PDT in different patient populations and subtypes of BCC. The outcomes of topical PDT are discussed in comparison with alternative treatments, and topical PDT applications in combination and adjuvant therapy are considered. The intention is to summarize the clinical relevance and expose areas of research need in the BCC context, ultimately to facilitate improvements in PDT treatment.

The use of the photodynamic method in the treatment of recurrent basal cell carcinoma on the example of Gorlin-Goltz syndrome-management algorithm

INTRODUCTION

Conventional methods of basal cell carcinomas (BCC) treatment bring many severe side effects, especially, if they are repeated many times. The aim of this study is to present the clinical effectiveness of photodynamic method in the treatment and prevention of BCC relapses on the face and to propose a management algorithm.

METHODS

In a patient with Gorlin-Goltz syndrome (NBCCS) lesions on the face were assessed clinically and with photodynamic diagnostics (PDD), initially and in follow-up every 3 months, for a total of 12 months. Detected BCCs were treated with photodynamic therapy three times every week.

RESULTS

In whole follow-up period no clinical relapses were shown. However, in PDD after 6 month in one irradiated and in one initially clinically clear area red fluorescence indicating atypical foci was observed and irradiated additional one time.

DISCUSSION

Photodynamic therapy is not limited by previous treatments, can be repeated without adverse events, heals multiple lesions at once and prevents new ones. Because BCC in NBCCS will occur constantly, the implementation of PDD to control the condition of the skin in long-term care should be obligatory. We indicate the validity of using the photodynamic diagnostic and therapy, as a medical procedures of choice.

Gorlin Syndrome

Gorlin syndrome is a rare autosomal dominant disease caused by mutations in the sonic hedgehog signaling pathway. Of particular importance is the PTCH1 gene. The disease is characterized by the development of multiple basal cell carcinomas at young ages. These tumors may present with other skin manifestations such as palmoplantar pits and with extracutaneous manifestations such as odontogenic keratocysts and medulloblastoma. Although the dermatologist may be key for recognizing clinical suspicion of the syndrome, a multidisciplinary team is usually necessary for diagnosis, treatment, and follow-up. Skin treatment may be complicated due to the large number of basal cell carcinomas and the extent of involvement. In recent years, new drugs that inhibit targets in the sonic hedgehog pathway have been developed. Although these agents appear promising options for patients with Gorlin syndrome, their efficacy is limited by adverse effects and the development of resistance.

Spectrum of orocutaneous disease associations: Genodermatoses and inflammatory conditions

The oral cavity and cutaneous organ systems share a close embryologic origin. Therefore, there are numerous dermatologic conditions presenting with concomitant oral findings of which the dermatologist must be aware. The second article in this continuing medical education series reviews inflammatory orocutaneous conditions and a number of genodermatoses. It is essential for dermatologists to be familiar with oral cavity manifestations associated with dermatologic diseases for prompt diagnosis, management, and appropriate referral to stomatology and dentistry.

Effects of photodynamic therapy on dermal fibroblasts from xeroderma pigmentosum and Gorlin-Goltz syndrome patients

PDT is widely applied for the treatment of non-melanoma skin cancer pre-malignant and malignant lesions (actinic keratosis, basal cell carcinoma and in situ squamous cell carcinoma). In photodynamic therapy (PDT) the interaction of a photosensitizer (PS), light and oxygen leads to the formation of reactive oxygen species (ROS) and thus the selective tumor cells eradication. Xeroderma pigmentosum (XP) and Gorlin-Goltz Syndrome (GS) patients are at high risk of developing skin cancer in sun-exposed areas. Therefore, the use of PDT as a preventive treatment may constitute a very promising therapeutic modality for these syndromes. Given the demonstrated role of cancer associated fibroblasts (CAFs) in tumor progression and the putative CAFs features of some cancer-prone genodermatoses fibroblasts, in this study, we have further characterized the phenotype of XP and GS dermal fibroblasts and evaluated their response to methyl-δ-aminolevulinic acid (MAL)-PDT compared to that of dermal fibroblasts obtained from healthy donors. We show here that XP/GS fibroblasts display clear features of CAFs and present a significantly higher response to PDT, even after being stimulated with UV light, underscoring the value of this therapeutic approach for these rare skin conditions and likely to other forms of skin cancer were CAFs play a major role.

Photodynamic Therapy and Non-Melanoma Skin Cancer

Non-melanoma skin cancer (NMSC) is the most common malignancy among the Caucasian population. Photodynamic therapy (PDT) is gaining popularity for the treatment of basal cell carcinoma (BCC), Bowen's disease (BD) and actinic keratosis (AK). A topical or systemic exogenous photosensitiser, results in selective uptake by malignant cells. Protoporphyrin IX (PpIX) is produced then activated by the introduction of a light source. Daylight-mediated MAL (methyl aminolaevulinate) PDT for AKs has the advantage of decreased pain and better patient tolerance. PDT is an effective treatment for superficial BCC, BD and both individual and field treatment of AKs. Excellent cosmesis can be achieved with high patient satisfaction. Variable results have been reported for nodular BCC, with improved outcomes following pretreatment and repeated PDT cycles. The more aggressive basisquamous, morphoeic infiltrating subtypes of BCC and invasive squamous cell carcinoma (SCC) are not suitable for PDT. Prevention of "field cancerization" in organ transplant recipients on long-term immunosuppression and patients with Gorlin syndrome (naevoid basal cell carcinoma syndrome) is a promising development. The optimisation of PDT techniques with improved photosensitiser delivery to target tissues, new generation photosensitisers and novel light sources may expand the future role of PDT in NMSC management.

In situ production of ROS in the skin by photodynamic therapy as a powerful tool in clinical dermatology

Photodynamic therapy (PDT) is a clinical modality of photochemotherapy based on the accumulation of a photosensitizer in target cells and subsequent irradiation of the tissue with light of adequate wavelength promoting reactive oxygen species (ROS) formation and cell death. PDT is used in several medical specialties as an organ-specific therapy for different entities. In this review we focus on the current dermatological procedure of PDT. In the most widely used PDT protocol in dermatology, ROS production occurs by accumulation of the endogenous photosensitizer protoporphyrin IX after treatment with the metabolic precursors 5-methylaminolevulinic acid (MAL) or 5-aminolevulinic acid (ALA). To date, current approved dermatological indications of PDT include actinic keratoses (AK), basal cell carcinoma (BCC) and in situ squamous cell carcinoma (SCC) also known as Bowen disease (BD). With regards to AKs, PDT can also treat the cancerization field carrying an oncogenic risk. In addition, an increasing number of pathologies, such as other skin cancers, infectious, inflammatory or pilosebaceous diseases are being considered as potentially treatable entities with PDT. Besides the known therapeutic properties of PDT, there is a modality used for skin rejuvenation and aesthetic purposes defined as photodynamic photorejuvenation. This technique enables the remodelling of collagen, which in turn prevents and treats photoaging stygmata. Finally we explore a new potential treatment field for PDT determined by the activation of follicular bulge stem cells caused by in situ ROS formation.

Diagnosis and Management of Hereditary Basal Cell Skin Cancer

Basal cell carcinoma (BCC) is the most common cancer in Caucasians worldwide and its incidence is rising. It is generally considered a sporadic tumour, most likely to affect fair-skinned individuals exposed to ultraviolet (UV) radiation. This chapter focusses on the approach to recognising the relatively few individuals in whom a high-risk hereditary susceptibility may be present. Gorlin syndrome is the main consideration and the gene most commonly mutated is PTCH1, a key regulator of the Hedgehog developmental pathway. Recently, loss of function of another gene in the same pathway, SUFU, has been found to explain a subset of families. Understanding the pathogenesis of familial BCCs has advanced the understanding of the biology of sporadic tumours and led to targeted therapy trials. The management of familial BCCs remains a challenge due to significant unmet needs for non-surgical treatments and a high burden of disease for the individual. Together with the prospect of advances in gene discovery and translation, these challenges highlight the need for ongoing review of at-risk and affected individuals by a multidisciplinary team.

Basal cell naevus syndrome: an update on genetics and treatment

Basal cell naevus syndrome is an autosomal dominant disorder that stems from mutations in multiple genes, most commonly patched 1 (PTCH1). The classic triad of symptoms consists of basal cell carcinomas, jaw keratocysts and cerebral calcifications, although there are many other systemic manifestations. Because of the broad range of symptoms and development of several types of tumours, early diagnosis and close monitoring are essential to preserve quality of life. Targeting treatment is often difficult because of tumour prevalence. Newer inhibitors of the hedgehog signalling pathway and proteins involved in proliferative growth have shown therapeutic promise. In addition, preventive medications are being devised. We propose a method for determining appropriate treatment for cutaneous tumours.

Photodynamic therapy for basal cell carcinoma

Topical photodynamic therapy is an effective and safe noninvasive treatment for low-risk basal cell carcinoma, with the advantage of an excellent cosmetic outcome. Efficacy of photodynamic therapy in basal cell carcinoma is supported by substantial research and clinical trials. In this article, we review the procedure, indications and clinical evidences for the use of photodynamic therapy in the treatment of basal cell carcinoma.

Review of Ocular Manifestations of Nevoid Basal Cell Carcinoma Syndrome: What an Ophthalmologist Needs to Know

Nevoid basal cell carcinoma syndrome (NBCCS) is a rare, autosomal dominant disorder characterized by multiple basal cell carcinomas (BCCs), odontogenic keratocysts, palmar and/or plantar pits, and ectopic calcifications of the falx cerebri. Myriad ophthalmologic findings are associated with NBCCS, including periocular BCCs, hypertelorism, strabismus, myelinated nerve fibers, and disorders of the retina and retinal pigment epithelium. We performed a literature search in PubMed for articles on the ophthalmologic manifestations of Gorlin syndrome, published between 1984 and 2014. Of 33 papers, 31 were included. Although Gorlin syndrome is due to mutations in a single gene, it displays variable phenotypic expressivity. Therefore, familiarity with this disorder across clinical specialties is necessary to avoid misdiagnosis. The ophthalmologist should be included in the multidisciplinary team for the management of Gorlin syndrome in order to prevent visual loss and improve the quality of life of these patients.

Usefulness of Photodynamic Therapy as a Possible Therapeutic Alternative in the Treatment of Basal Cell Carcinoma

Basal cell carcinoma (BCC) is the most common cancer in individuals with fair skin type (I–II) and steadily increasing in incidence (70% of skin malignancy). It is locally invasive but metastasis is usually very rare, with an estimated incidence of 0.0028%–0.55%. Conventional therapy is surgery, especially for the H region of the face and infiltrative lesions; in case of inoperable tumors, radiotherapy is a valid option. Recently, topical photodynamic therapy (PDT) has become an effective treatment in the management of superficial and small nodular BCC. PDT is a minimally invasive procedure that involves the administration of a photo-sensibilizing agent followed by irradiation at a pre-defined wavelength; this determines the creation of reactive oxygen species that specifically destroy target cells. The only major side effect is pain, reported by some patients during the irradiation. The high cure rate and excellent cosmetic outcome requires considering this possibility for the management of patients with both sporadic and hereditary BCC. In this article, an extensive review of the recent literature was made, in order to clarify the role of PDT as a possible alternative therapeutic option in the treatment of BCC.

Dual roles of nitric oxide in the regulation of tumor cell response and resistance to photodynamic therapy

Photodynamic therapy (PDT) against cancer has gained attention due to the successful outcome in some cancers, particularly those on the skin. However, there have been limitations to PDT applications in deep cancers and, occasionally, PDT treatment resulted in tumor recurrence. A better understanding of the underlying molecular mechanisms of PDT-induced cytotoxicity and cytoprotection should facilitate the development of better approaches to inhibit the cytoprotective effects and also augment PDT-mediated cytotoxicity. PDT treatment results in the induction of iNOS/NO in both the tumor and the microenvironment. The role of NO in cytotoxicity and cytoprotection was examined. The findings revealed that NO mediates its effects by interfering with a dysregulated pro-survival/anti-apoptotic NF-κB/Snail/YY1/RKIP loop which is often expressed in cancer cells. The cytoprotective effect of PDT-induced NO was the result of low levels of NO that activates the pro-survival/anti-apoptotic NF-κB, Snail, and YY1 and inhibits the anti-survival/pro-apoptotic and metastasis suppressor RKIP. In contrast, PDT-induced high levels of NO result in the inhibition of NF-kB, Snail, and YY1 and the induction of RKIP, all of which result in significant anti-tumor cytotoxicity. The direct role of PDT-induced NO effects was corroborated by the use of the NO inhibitor, l-NAME, which reversed the PDT-mediated cytotoxic and cytoprotective effects. In addition, the combination of the NO donor, DETANONOate, and PDT potentiated the PDT-mediated cytotoxic effects. These findings revealed a new mechanism of PDT-induced NO effects and suggested the potential therapeutic application of the combination of NO donors/iNOS inducers and PDT in the treatment of various cancers. In addition, the study suggested that the combination of PDT with subtoxic cytotoxic drugs will result in significant synergy since NO has been shown to be a significant chemo-immunosensitizing agent to apoptosis.

•

PDT-mediated cytotoxic and cytoprotective effects depend also by the induction of NO from tumor.

•

The PDT-induced NO modulates the dysregulated NF-kB/Snail/RKIP loop.

•

The direct role of NO induction by PDT was corroborated by the use of the NO inhibitor, l-NAME.

•

The combination of an NO donor and PDT resulted in a increased cytotoxic effect, in vitro and in vivo.

•

Novel potential therapeutic applications are proposed for the use of PDT combined with NO donors.

Current evidence and applications of photodynamic therapy in dermatology

In photodynamic therapy (PDT) a photosensitizer – a molecule that is activated by light – is administered and exposed to a light source. This leads both to destruction of cells targeted by the particular type of photosensitizer, and immunomodulation. Given the ease with which photosensitizers and light can be delivered to the skin, it should come as no surprise that PDT is an increasingly utilized therapeutic in dermatology. PDT is used commonly to treat precancerous cells, sun-damaged skin, and acne. It has reportedly also been used to treat other conditions including inflammatory disorders and cutaneous infections. This review discusses the principles behind how PDT is used in dermatology, as well as evidence for current applications of PDT.