Methylaminolaevulinate-based photodynamic therapy of Bowen's disease and squamous cell carcinoma.

BACKGROUND: Photodynamic therapy (PDT) with methylaminolaevulinate (MAL) is an approved noninvasive treatment option for actinic keratosis and Bowen's disease (BD), two precursors of invasive squamous cell carcinoma (SCC). OBJECTIVES: To assess efficacy, prognostic features, tolerability and cosmetic outcome of MAL-PDT for the treatment of BD and SCC. METHODS: In total, 112 biopsy-proven lesions of BD and SCC in 55 subjects were treated in an outpatient setting. MAL cream (160 mg g(-1)) was applied for 3 h prior to illumination with a light-emitting diode source (wavelength range 635 +/- 18 nm; light dose 37 J cm(-2)). A second MAL-PDT session was given 7 days later. Complete response rate at 3 months after the last treatment, recurrence rate at the 24-month follow-up, and cosmetic outcome were recorded. RESULTS: The overall complete response rates were 73.2% at 3 months and 53.6% at 2 years. Clinical thickness, atypia and lesion depth were significant predictors of the response at 3 months when using a univariate analysis (P < 0.001). A multivariate logistic regression model, with robust variance estimation, showed that cell atypia was the only statistically significant independent predictor of the treatment outcome at 3 months. CONCLUSIONS: MAL-PDT may represent a valuable, effective and well tolerated treatment option with good cosmetic outcome for superficial, well-differentiated (Broders' scores I and II) BD and microinvasive SCC. In contrast, its use for superficial SCCs with a microinvasive histological pattern and for nodular, invasive lesions, particularly if poorly differentiated keratinocytes are present (Broders' scores III and IV), should be avoided.

Photodynamic therapy of interdigital mycoses of the feet with topical application of 5-aminolevulinic acid.

BACKGROUND: Findings of in vitro studies have demonstrated that dermatophytes and yeasts can be effectively photosensitized after topical delivery of 5-aminolevulinic acid (ALA). This procedure, called photodynamic therapy (PDT), seems to lack mutagenic activity and hazard of selection of drug-resistant strains. METHODS: Twenty percent ALA preparation in Eucerin cream was applied under an occlusive dressing to skin lesions of nine patients with clinical and microbiological evidence of interdigital mycosis of the feet. After 4 h, lesions were irradiated with 75 J/cm(2) of broad-band red light. Interdigital lesions of the other foot served as control (treated with only light or only ALA). After 7 days from the first treatment, no further treatment was delivered if lesions were not clinically evident and direct microscopic examination was negative. Otherwise, three additional weekly treatments were delivered. Four weeks after the last treatment, patients had a final follow-up clinical and laboratory examination. RESULTS: Clinical and microbiological recovery was seen in six out of nine patients after one (four cases) or four (two cases) treatments. However, after 4 weeks, recurrences were seen in four patients. Overall tolerability was always good. CONCLUSION: Under the conditions employed in the present study, ALA-PDT had good therapeutic effects on interdigital mycosis of the feet. However, recurrences were quick. In vivo environmental conditions, i.e. temperature, humidity and pH of the interdigital skin, could induce a poor cell uptake of ALA and a deficient biosynthesis of photosensitizing protoporphyrin IX. In addition, the irregular tridimensional shape of this peculiar anatomical area could lead to a non-uniform delivery of light and/or ALA cream. However, the present results can stimulate further studies on the PDT of superficial skin mycoses.

Photosensitive erythema multiforme and erythema multiforme-like polymorphous light eruption.

BACKGROUND: Photosensitive erythema multiforme (EM) is a rare disorder. It usually occurs only if a herpes virus infection or ingestion of drugs precedes exposure to sunlight in selected patients. METHODS: We report a 37-year-old man who had recurrent EM eruptions following sun exposures over a period of 20 years. Lesions were prevalently located on exposed skin, but unexposed skin and mucosa of the oropharynx were also affected. The patient had poor tolerance to sunlight and denied having herpes simplex infection or using drugs. RESULTS: Provocative phototest induced clinically and histologically similar lesions at low dose thresholds of UVA (10 J/cm2) and UVB (100 mJ/cm2). CONCLUSION: On the basis of clinical and histological findings and results of phototesting, a diagnosis of photosensitive EM was made. The EM-like variant of polymorphous light eruption is discussed in the differential diagnosis.