5-Aminolevulinic acid-based photodynamic therapy for the treatment of two patients with extramammary Paget's disease

Photodynamic therapy (PDT), which employs a combination of a tumor-localizing photosensitizer and visible light, has been used in the treatment of extramammary Paget's disease (EMPD). Two patients with EMPD were treated with PDT using 5-aminolevulinic acid (ALA). Histologically, in both cases, Paget's cells were present within the epidermis. Case 1 was a 92-year-old male who underwent total extirpation for treatment of EMPD. Two topical ALA-PDT treatments were applied to parts of the lesions at a total dose of 200J/cm2. Case 2 was a 73-year-old female, whose lesions in the right labia majora were treated with 3 topical ALA-PDT sessions at a total dose of 300 J/cm2. Clinical findings after the irradiation showed improvement in both patients, and elimination of tumor cells in the epidermis was confirmed histologically. Case 1 had no recurrence in the irradiation field at three months after PDT. Case 2 had a recurrence only in the periphery parts of the lesions at two months after PDT, but the periphery lesions remitted with two more PDT treatments. Topical ALA-PDT is an effective treatment for EMPD with tumor cells within the epidermis. It is noninvasive and achieves a cosmetically excellent outcome, especially in elderly patients and those in poor general condition.     

Topical 5-aminolaevulinic acid-photodynamic therapy for the treatment of urethral condylomata acuminata

BACKGROUND: Electrocoagulation and laser evaporation for urethral condylomata acuminata have high recurrence rates and can be associated with urethral malformations. OBJECTIVES: To investigate the effect of photodynamic therapy (PDT) with topical 5-aminolaevulinic acid (ALA) on urethral condylomata acuminata and to examine the histological changes in lesions of condylomata acuminata after ALA-PDT. METHODS: Patients with urethral condylomata (n = 164) were given topical ALA followed by intraurethral PDT through a cylindrical fibre. Patients included 11 individuals with 16 penile or vulval condylomatous lesions which were biopsied before or after treatment; the histological changes were then evaluated by light microscopy and electron microscopy. RESULTS: The complete response rate was 95% and the recurrence rate was 5% after 6-24 months of follow-up. Light microscopy revealed keratinocytes in the middle and upper layers of the epidermis showing marked vacuolation and some necrocytosis 1 and 3 h after PDT. Necrosis in all layers of the epidermis was noted 5 h after PDT. Electron microscopy of keratinocytes revealed distinct ultrastructural abnormalities of mitochondria and the endoplasmic reticulum, and membrane damage. Apoptotic bodies were detected 3 h after PDT and a large number of keratinocytes exhibited necrosis 5 h after PDT. CONCLUSIONS: Results suggest that, compared with conventional therapies, topical ALA-PDT is a simple, effective, safe and well-tolerated treatment for urethral condylomata acuminata that is associated with a low recurrence rate. The mechanism might be the triggering of both apoptosis and necrosis by ALA-PDT in human papillomavirus-infected keratinocytes.     

Randomized comparison of photodynamic therapy with topical 5-fluorouracil in Bowen's disease

BACKGROUND: Bowen's disease (BD; intraepithelial squamous cell carcinoma) is therapeutically challenging because lesions, which may be multiple, are frequently located at sites that heal poorly. There is a small risk of progression to invasive carcinoma. Photodynamic therapy (PDT) is an effective treatment for certain non melanoma skin cancers, but comparison studies with other, better-established therapies are limited. OBJECTIVES: To compare the efficacy and tolerability of PDT and topical 5-fluorouracil (5-FU) in BD. METHODS: Forty patients from two centres were randomized to either topical PDT or 5-FU. The PDT group was treated with 20% 5-aminolaevulinic acid (ALA) applied 4 h before illumination with 100 J cm-2 narrowband red light (630 +/- 15 nm). 5-FU was applied to lesions for 4 weeks. A repeat treatment cycle was performed after 6 weeks if required. Results Twenty-nine of 33 (88%) lesions treated with PDT initially responded completely, compared with 22 of 33 (67%) after 5-FU. After 12 months, two recurrences in the PDT group and six in the 5-FU group reduced complete clinical clearance rates to 82% and 48%, respectively. PDT was significantly more effective (P = 0.006, odds ratio 4.78, 95% confidence interval 1.56-14.62). In the 5-FU group, severe eczematous reactions developed around seven lesions, ulceration in three and erosions in two. No such reactions occurred following PDT. There was no difference in overall pain experienced during each therapy. CONCLUSIONS: Topical ALA-PDT is more effective than topical 5-FU in the treatment of BD, with fewer adverse events. ALA-PDT should be considered one of the first-line therapeutic options for BD.     

Successful treatment of lymphadenosis benigna cutis with topical photodynamic therapy with delta-aminolevulinic acid

BACKGROUND: Photodynamic therapy (PDT) using topical delta-aminolevulinic acid (ALA) has been used for nonmelanoma skin cancers, including malignant cutaneous T-cell lymphomas. Moreover, PDT has been tried for benign inflammatory or infectious skin lesions. OBJECTIVE: To evaluate the effects of ALA-PDT on skin lesions of lymphadenosis benigna cutis (LABC). PATIENTS AND METHODS: Two 16-year-old females with solitary and infiltrated nodules were treated 5 times with topical ALA-PDT. RESULTS: Both patients responded well and showed dramatic clinical and histopathological improvement without visible scars. CONCLUSION: The results confirm that topical ALA-PDT is an effective and safe modality for the treatment of LABC, and that such treatment may be cosmetically beneficial.     

Comparison of red and green light in the treatment of Bowen's disease by photodynamic therapy

BACKGROUND: A variety of protocols exist for the treatment of Bowen's disease by photodynamic therapy (PDT) using topical 5-aminolaevulinic acid (5-ALA). OBJECTIVE: To determine the optimal wavelength (red or green light) for this treatment. METHODS: A randomized comparison study of ALA-PDT using red (630 +/- 15 nm) or green (540 +/- 15 nm) light in the treatment of Bowen's disease. RESULTS: The initial clearance rate for lesions treated by red light was 94% (30 of 32) in comparison with 72% (21 of 29) for those lesions receiving green light (P = 0.002). Over the following 12 months, there were two recurrences in the red light group and seven in the green light group reducing the clearance rates to 88% and 48%, respectively. The frequency and severity of pain experienced were similar between the two treatment groups. No hyperthermia, nor significant difference in lesional temperatures, was observed between the wavelengths studied. CONCLUSION: Green light is less effective than red light, at a theoretically equivalent dose, in the treatment of Bowen's disease by topical ALA-PDT.     

Non-oncologic indications for ALA-PDT

Topical photodynamic therapy with 5-aminolevulinic acid (ALA-PDT) is a well-established treatment regimen for superficial epithelial skin tumours, but it is evident that inflammatory diseases of the skin and virus-induced lesions can also profit from PDT. Depending on the light dose applied, either cytotoxic effects resulting in tumour destruction or immunomodulatory effects resulting in improvement of inflammatory conditions occur. Patients with localized scleroderma that had been unresponsive to various treatments, including PUVA or bath-PUVA therapy, respond very well to topical ALA-PDT performed repeatedly. In contrast to PUVA therapy, no carcinogenic potential is being discussed for PDT. Also, HPV-induced skin lesions might provide a possible indication for topical ALA-PDT. The rapidly proliferating cells in viral acanthomas accumulate ALA-induced protoporphyrin IX (PPIX) selectively when compared to the surrounding non-infected cells. The efficacy of topical ALA-PDT in the treatment of recalcitrant foot and hand warts has been shown in a placebo-controlled, randomized, double-blind trial. Furthermore, case reports describe a good response of other virus-induced diseases, for example condylomata acuminata and epidermodysplasia verruciformis, to topical PDT with ALA. However, controlled clinical trials are still needed to demonstrate more fully the effectiveness of PDT for inflammatory skin diseases.     

Topical aminolevulinic acid-photodynamic therapy for the treatment of acne vulgaris

BACKGROUND: Photodynamic therapy (PDT) is useful for the treatment of epidermal neoplasia but may also have use in the treatment of inflammatory dermatoses. The purpose of this study was to evaluate the safety and efficacy of PDT in the treatment of acne on the face. METHODS: Eight patients with mild-to-moderate acne vulgaris on the face were treated with one session of topical aminolevulinic acid (ALA)-PDT using a red light. Each patient's face was divided into two areas (right side and left side) for ALA-PDT and untreated control. Twenty percent topical ALA was applied with 4 h occlusion, and 18 J/cm(2) red light (630+/-63 nm) was administered. Each patient's acne was visually assessed by a spot count of both inflamed and non-inflamed lesions at baseline and at 1, 3, and 6 months following PDT. RESULTS: At 1, 3, and 6 months, the mean percentage reduction in inflamed lesions count was 27.6%, 37.9%, and 41.9%, respectively, in the ALA-PDT-treated area, whereas in the control area, it was 8.0%, 14.7%, and 15.4%, respectively, compared with the baseline. This showed a higher reduction of a spot count of inflamed lesions in the ALA-PDT-treated area, which was statistically significant (P<0.05). There was a slightly higher reduction of a spot count of non-inflamed lesions in the ALA-PDT-treated area, which was statistically not significant (P>0.05). The adverse effects were minimal. CONCLUSION: ALA-PDT with red light was found to be effective in the reduction of the number of inflamed lesions in patients with mild-to-moderate acne vulgaris, with no significant short-term adverse effects.     

5-氨基酮戊酸乳膏光动力疗法治疗皮肤癌前病变和皮肤原位癌

目的 探讨5-氨基酮戊酸光动力疗法(ALA-PDT)治疗皮肤癌前病变和皮肤原位癌的疗效.方法 对15例光线性角化病、3例Queyrat增生性红斑和8例Bowen病患者进行ALA-PDT治疗.结果 15例光线性角化病患者的17个皮损获得完全缓解,2例复发,复发率13.33%;3例Queyrat增生性红斑除1例无效外,另2例患者的皮损获完全缓解,无复发;8例Bowen病除1例获得部分缓解外,其他7例完全缓解,1例复发.结论 ALA-PDT是一种疗效好、无明显痛苦、无瘢痕形成、复发率低、美容效果好的治疗皮肤癌前病变和皮肤原位癌的新疗法;特别适合于头面部及外生殖器部位的多发性、较大面积皮损.     

Photodynamic therapy vs. cryosurgery of basal cell carcinomas: results of a phase III clinical trial

BACKGROUND: A previously reported randomized clinical trial showed treatment of Bowen's disease using photodynamic therapy (PDT) with topically applied delta-aminolaevulinic acid (ALA) to be at least as effective as cryosurgery and to be associated with fewer adverse effects. OBJECTIVES: To compare ALA-PDT and cryotherapy in the treatment of histopathologically verified basal cell carcinomas (BCCs) in a non-blinded, prospective phase III clinical trial. METHODS: One lesion from each of 88 patients was included. The BCCs were divided into superficial and nodular lesions. The follow-up period was restricted to 1 year with close follow-up for the first 3 months. Efficacy was assessed as the recurrence rate 12 months after the first treatment session, verified by histopathology. Tolerability was evaluated as the time of healing, pain and discomfort during and after the treatment, and final cosmetic outcome. RESULTS: Histopathologically verified recurrence rates in the two groups were statistically comparable and were 25% (11 of 44) for ALA-PDT and 15% (six of 39) for cryosurgery. However, clinical recurrence rates were only 5% (two of 44) for PDT and 13% (five of 39) for cryosurgery. Additional treatments, usually one, had to be performed in 30% of the lesions in the PDT group. The healing time was considerably shorter and the cosmetic outcome significantly better with PDT. Pain and discomfort during the treatment session and in the following week were low, and were equivalent with the two treatment modalities. CONCLUSIONS: In terms of efficacy, ALA-PDT is comparable with cryosurgery as a treatment modality for BCCs. Retreatments are more often required with PDT than with cryosurgery. This can easily be performed due to the shorter healing time, less scarring and better cosmetic outcome that follows ALA-PDT.     

Comparative study of photodynamic therapy vs CO2 laser vaporization in treatment of condylomata acuminata: a randomized clinical trial

BACKGROUND: Most conventional therapies for condylomata acuminata (CA) are traumatic and have high recurrence rates. OBJECTIVES: To investigate the efficacy and safety of topical application of 5-aminolaevulinic acid (ALA) photodynamic therapy (PDT) for the treatment of CA. METHODS: Sixty-five patients with CA were allocated into the treatment (ALA-PDT) group and treated with 20% ALA solution under occlusive dressing for 3 h followed by irradiation with the helium-neon laser at a dose of 100 J cm(-2) and a power of 100 mW. Another 21 CA patients were allocated into the control group and treated with the CO(2) laser. The treatment was to be repeated 1 week later if the lesion was not completely removed after the first treatment. RESULTS: After one treatment, the complete removal rate was 95% in the ALA-PDT group and 100% in the control group. After two treatments with ALA-PDT, the complete removal rate in the treatment group was 100%. The recurrence rate for ALA-PDT group was 6.3% which was significantly lower than that in control group (19.1%, P < 0.05). Moreover, the proportion of patients with adverse effects in the ALA-PDT group (13.9%) was also significantly lower than that in control group (100%, P < 0.05). The side-effects in patients treated with ALA-PDT mainly included mild burning and/or stinging restricted to the illuminated area. CONCLUSIONS: The present study shows that topical application of ALA-PDT is a simpler, more effective and safer therapy with a lower recurrence for treatment of CA compared with conventional CO(2) laser therapy.     

ALA-PDT治疗囊肿性痤疮22例疗效观察

目的采用随机对照研究评价3%5-氨基酮戊酸光动力疗法(ALA-PDT)治疗囊肿性痤疮的疗效。方法治疗组22例接受1～3次ALA-PDT,对照组17例口服异维A酸胶丸20mg/d。皮损消退>90%或治疗持续6周为研究终点。结果治疗组第2,4,6周囊肿数目较对照组明显减少(P<0.01);治疗组第2,4,6周有效率分别为9.09%,40.91%,100%,而对照组分别为0,11.76%,58.82%,差异有统计学意义(P均<0.05);B超显示ALA-PDT治疗后囊肿较治疗前缩小或消失(P<0.01)。研究结束时,治疗组患者满意度较对照组高(P<0.05);治疗组复发率较对照组明显降低(P<0.05),且首次复发时间较对照组延长(P<0.05)。结论 ALA-PDT能够安全快速治愈囊肿性痤疮,同时延迟复发。     

ALA光动力治疗鲍温样丘疹病临床研究

目的观察5氨基酮戊酸(5aminolevulinicacid,ALA)光动力疗法(photodynamictherapy,PDT)治疗鲍温样丘疹病的临床疗效。方法治疗组38例采用ALAPDT治疗,每周治疗1次,共治疗4次;对照组15例予以二氧化碳激光治疗。结果治疗组痊愈12例,显效12例,有效率为61.2%,复发2例,复发率16.7%,无明显疼痛、创面等副作用;对照组痊愈9例,显效3例,有效率为80.0%,复发5例,复发率55.5%,15例均有术后明显创面疼痛,8例合并创面感染,9例出现表浅瘢痕。两组之间有效率和复发率无显著性差异(P>0.05)。结论ALAPDT是治疗鲍温样丘疹病的一种安全、有效、无明显痛苦和不良反应的新疗法。     

Intraindividual, right–left comparison of topical 5-aminolevulinic acid photodynamic therapy vs. 5% imiquimod cream for actinic keratoses on the upper extremities

Backround  Actinic keratoses (AKs) are considered as in situ squamous cell carcinoma. Early and effective treatment is important.
Objective  To compare the efficacy, cosmetic outcome and patient preference of 5-aminolevulinic acid photodynamic therapy (ALA-PDT) with that of 5% imiquimod (IMIQ) cream in patients with AKs on the dorsa of hands and forearms.
Methods  Subjects received two ALA-PDT treatment sessions and one or two courses of imiquimod (three times per week for 4 weeks each). Treatments were randomly allocated to alternate upper extremities. Assessments included lesion response one and six months after treatment, cosmetic outcome evaluated by the investigators and patients' preference 6 months after treatment. Efficacy end point included the individual AK lesion clearance rate.
Results  Thirty patients with 256 lesions were included in the study. At the first follow-up, treatment with ALA-PDT resulted in significantly larger rate of cured lesions relative to 5% IMIQ cream (70.16% vs. 18.26%). At the second follow-up both treatments showed a high rate of cured lesions (65.32% for PDT vs. 55.65% for IMIQ cream). Response rates obtained in grade I lesions were higher for both treatments (71.64% for PDT vs. 72.13% for IMIQ), while treatment with PDT resulted in a significant larger rate of cured grade II lesions (57.89% for PDT vs. 37.03 for IMIQ).
Difference in cosmetic outcome was not statistically significant. Results for subject preference favoured ALA-PDT.
Conclusions  Our study shows that ALA-PDT and 5% IMIQ cream are both attractive treatment options for upper extremities AKs with comparable efficacy and cosmetic outcomes.

Conflicts of interest

None declared.     

Evidence for a bystander role of neutrophils in the response to systemic 5-aminolevulinic acid-based photodynamic therapy

BACKGROUND/PURPOSE: A significant increase in the number of circulating and tumour neutrophils immediately after therapy was observed while investigating the increase in response of tissues to aminolevulinic acid-based photodynamic therapy (ALA-PDT) using a twofold illumination scheme with a prolonged dark interval. The action of (tumour) neutrophils is an important therapeutic adjunct to the deposition of singlet oxygen within the treatment volume, for many photosensitizers. It is not known if those phagocytes contribute to the improved outcome of ALA-PDT. In this study we investigated the role of neutrophils in the response to PDT using systemic ALA with and without light fractionation. METHODS: Rhabdomyosarcoma, transplanted in the thigh of female WAG/Rij rats were illuminated transdermally using 633 nm light following i.v. administration of 200 mg/kg ALA. The pharmacokinetics of protoporphyrin IX (PpIX) within the tumour tissue during therapy were determined to compare with that observed in other models for topical administration of ALA. PDT was performed under immunologically normal or neutropenic conditions using various illumination schemes. The number of neutrophils in tumour and in the circulation were determined as a function of time after treatment and compared with growth delay of each scheme. RESULTS: Fluorescence spectroscopy revealed similar pharmacokinetics of PpIX to those observed during and after topical ALA-PDT. The number of neutrophils within the illuminated tumour and in the circulation increased significantly following therapy. This increase in the number of neutrophils was associated with an increase in the efficacy of therapy: the more effective the therapy the greater the increase in tumour and blood neutrophils. Administration of anti-granulocyte serum treatment prevented the influx of neutrophils after ALA-PDT, but did not lead to a significant decrease in the efficacy of the PDT treatment on the growth of the tumour for any illumination scheme investigated. CONCLUSION: These results indicate that the magnitude of damage inflicted on the tumour by ALA-PDT does not depend on the presence of neutrophils in the tumour or circulation and that the role of neutrophils in ALA-PDT is much less important than in PDT using other photosensitizers. These data contribute to the understanding of the mechanism of response of tissue to systemic ALA-PDT.     

δ-氨基酮戊酸光动力学疗法治疗皮肤病的研究进展

δ-氨基酮戊酸光动力学疗法是一种非创伤性局部治疗技术,可特异性杀死病变细胞.近年研究表明,该疗法对靶细胞某些生物学特征的影响是重要作用机制之一.除非色素细胞性皮肤恶性肿瘤外,δ-氨基酮戊酸光动力学疗法的适应症逐渐扩展至癌前病变、病毒疣、痤疮、结缔组织病、光化性疾病等范围.升高温度、促溶剂、金属离子螫合物、电离子导入、脂质体载体等因素可促进其疗效.     

Incomplete efficacy of 5-aminolevulinic acid (5 ALA) photodynamic therapy in the treatment of widespread extramammary Paget's disease

Photodynamic therapy (PDT) using 5-aminolevulinic acid (5-ALA) is an effective treatment for several conditions such as Bowen's disease, subsets of basal cell carcinomas and actinic keratosis. Surgical resection is the first-choice therapy for extramammary Paget's disease (EMPD), but extensive resection is highly invasive and recurrences are frequent. We report two cases of genital EMPD treated by PDT with partial efficacy. The first patient, a 78-year-old male, suffered from pubic and scrotal Paget's disease for 6 years despite numerous treatments. The second patient, a 78-year-old female, had vulvar involvement for 2 years that was resistant to multiple treatments. The disease was recurrent and chronic with important pruritus and significant impact on the quality of life. Methyl 5-aminolevulinate was applied for 3 h, and irradiation was applied with red light (630 nm) using a total light dose of 37 J/cm(2) for a period of 10 min. The patients were treated every 2 to 4 weeks for a total of at least three treatments. Both patients experienced a partial transient reduction in their symptoms. One patient had a partial transient remission (< 50% reduction of the involved surface), whereas in the other patient, PDT failed to reduce the surface area of the lesions.     

Photodynamic therapy of epithelial skin tumours using delta-aminolaevulinic acid and desferrioxamine

Photodynamic therapy (PDT) uses photosensitizing drugs, such as porphyrins, and light for cancer treatment. In the present clinical study we employed topical application of the porphyrin precursor delta-aminolaevulinic acid (ALA) in combination with desferrioxamine (df) for the induction of endogenous porphyrin synthesis. Irradiation was performed with a light source consisting of a halogen lamp with a red filter and a fibreoptic device. Irradiances ranged from 50 to 300mW/cm². We treated 49 patients with this PDT regimen. In 32 patients we treated a total of 34 superficial basal cell carcinomas (BCCs) and 22 nodular BCCs, in nine patients 43 solar keratoses, and in eight patients 10 lesions of Bowen's disease. After a single treatment, 30 (88.2%) of the superficial and seven (31.8%) of the nodular BCCs, 35 of 43 (81.4%) solar keratoses. and three (30%) of the Bowen's disease lesions showed complete remission. The post-treatment observation period was up to 20 months. Repeat therapy was required in six nodular and four superficial BCCs. Biopsies were obtained before treatment, and at variable intervals after treatment. Topical PDT of skin tumours with ALA-df-induced porphyrins is effective in the management of epithelial skin tumours.     

Photodynamic therapy for large or multiple patches of Bowen disease and basal cell carcinoma

BACKGROUND: Photodynamic therapy (PDT) using topical delta-aminolevulinic acid (delta-ALA) is an effective treatment for Bowen disease and certain basal cell carcinomas (BCCs), but its place in clinical practice remains to be established. Patients with large and/or multiple lesions of Bowen disease or BCC can represent a considerable therapeutic challenge. We suggest that delta-ALA PDT may be of particular benefit in such patients. OBSERVATION: In an open study, 35 (88%) of 40 large patches of Bowen disease, all with a maximum diameter greater than 20 mm, cleared following 1 to 3 treatments of delta-ALA PDT, although 4 patches recurred within 12 months. delta-Aminolevulinic acid PDT was also used to treat 40 large BCCs, with an identical 88% initial clearance (after 1-3 treatments), with 4 recurrences within 34 months (range, 12-60 months). In 10 further patients with multiple (> or =3) patches of Bowen disease, 44 (98%) of 45 patches cleared following delta-ALA PDT, although 4 lesions recurred over 12 months. In 3 patients with multiple BCCs, PDT cleared 52 (90%) of 58 lesions, with 2 recurrences during 41 months (range, 12-52 months). Treatments were well tolerated, with only 5 patients with solitary large lesions requiring local anesthesia. CONCLUSIONS: delta-Aminolevulinic acid PDT is an effective tissue-sparing modality achieving good cosmesis. We propose that delta-ALA PDT be considered as a first-line therapy for large and/or multiple areas of Bowen disease and superficial BCCs.     

Guidelines for topical photodynamic therapy: report of a workshop of the British Photodermatology Group

Topical photodynamic therapy (PDT) is effective in the treatment of certain non-melanoma skin cancers and is under evaluation in other dermatoses. Its development has been enhanced by a low rate of adverse events and good cosmesis. 5-Aminolaevulinic acid (ALA) is the main agent used, converted within cells into the photosensitizer protoporphyrin IX, with surface illumination then triggering the photodynamic reaction. Despite the relative simplicity of the technique, accurate dosimetry in PDT is complicated by multiple variables in drug formulation, delivery and duration of application, in addition to light-specific parameters. Several non-coherent and coherent light sources are effective in PDT. Optimal disease-specific irradiance, wavelength and total dose characteristics have yet to be established, and are compounded by difficulties comparing light sources. The carcinogenic risk of ALA-PDT appears to be low. Current evidence indicates topical PDT to be effective in actinic keratoses on the face and scalp, Bowen's disease and superficial basal cell carcinomas (BCCs). PDT may prove advantageous where size, site or number of lesions limits the efficacy and/or acceptability of conventional therapies. Topical ALA-PDT alone is a relatively poor option for both nodular BCCs and squamous cell carcinomas. Experience of the modality in other skin diseases remains limited; areas where there is potential benefit include viral warts, acne, psoriasis and cutaneous T-cell lymphoma. A recent British Photodermatology Group workshop considered published evidence on topical PDT in order to establish guidelines to promote the efficacy and safety of this increasingly practised treatment modality.