H. van Weelden

Photodynamic therapy with violet light and topical δ‐aminolaevulinic acid in the treatment of actinic keratosis, Bowen’s disease and basal cell carcinoma

Background Most clinical studies using photodynamic therapy (PDT) with topical application of δ‐aminolaevulinic acid (δ‐ALA) use red light because it allows greater depth of penetration. However, given the porphyrin‐like spectrum of δ‐ALA‐induced photosensitivity, violet light provides a maximal overlap with the excitation spectrum of protoporphyrin IX, meaning that PDT with violet light uses less light energy to induce the phototoxic reaction.

The carcinogenic risks of modern tanning equipment: Is UV-A safer than UV-B?

SummaryAn animal experiment is presented in which three groups of albino hairless mice (Skh-hr 1) were exposed to daily doses of either UV-B or UV-A to study carcinogenesis. The UV-A was filtered carefully so as to eliminate contaminating UV-B. The doses required for acute effects (erythema and edema) were also determined for the two radiation modalities. In order to study the relative carcinogenic risks of exposures to UV-A and to UV-B, for both modalities, the doses causing skin tumors were compared to the doses required for eliciting acute effects in the skin.In the experiment on carcinogenesis all animals developed tumors, the ones exposed to UV-A as well as the ones exposed to UV-B. A striking difference, however, was that the induction times of the first tumors showed a larger spread in the mice exposed to UV-A than in the UV-B groups. Also, the development of successive tumors in each individual mouse was more spread in time in the UV-A group. A second difference between the effects on the skin was that in the animals exposed to UV-B no skin reactions were seen until the tumors developed. However, in most UV-A exposed animals, a marked scratching, probably caused by severe itching, and hyperkeratosis preceded the development of the tumors.Histologically at least 60% of the larger tumors induced by UV-A appeared to be squamous cell carcinomas. This finding is very similar for UV-B induced tumors. The elastic fibers in the UV-A exposed animals were also examined and actinic elastosis was observed.Experience has proven that the doses for acute affects in man and mouse are at least proportional to human tanning doses. Comparison of the doses of UV-A and UV-B required for the induction of tumors and for acute reactions of the skin, therefore, leads to the conclusion that the carcinogenic risks of tanning by UV-A and of tanning by UV-B are in the same order of magnitude.

Light-induced skin lesions in lupus erythematosus: photobiological studies

SummaryTo investigate the light sensitivity to various wavelength regions in lupus erythematosus (LE), phototests were performed in 24 LE patients with clinical photosensitivity (7 had systemic LE, 9 discoid LE, and 8 subacute cutaneous LE). Skin areas (measuring 40–60 cm2) were irradiated daily, maximally six times. With all three light sources used (emitting UVB, UVA, and visible light respectively) abnormal papular or papulosquamous reactions could be induced. In four of the 20 patients reacting abnormally, lesions occurred 10 or more days after cessation of the phototests; this indicates that the problem of photosensitivity in LE may be greater than appreciated so far.

UVA-induced tumours in pigmented hairless mice and the carcinogenic risks of tanning with UVA.

SummaryAn animal experiment is presented in which two groups of pigmented hairless mice were exposed daily to suberythemal doses of UVA to study tumourigenesis. The aim of the study was to estimate the carcinogenic risks of tanning by UVA. The pigmented hairless mice, Skh-hr2, were separated by selective breeding into two groups, the “browns” and the “blacks”. Both groups were exposed daily to UVA from fluorescent UVA lamps (Philips TL40W/09) purified by rigorously filtering out the shorter wavelengths. No acute actinic damage was observed after any exposure. However, in most UVA exposed animals, especially in the blacks, a marked scratching preceded the development of tumours. Hyperkeratosis was also observed. All animals developed tumours. Histopathologically at least 60% of the tumours were squamous cell carcinomas. Depositions of melanophages were observed, but no melanomas. It is beyond any doubt that UVA is carcinogenic in laboratory animals. The present state of knowledge justifies no preference for tanning with UVA over tanning with UVB.

The dose-response relationship for tumourigenesis by UV radiation in the region 311 – 312 nm

Groups of hairless mice were irradiated daily with Philips TL01 UVB sources. This type of lamp has become available recently and was developed for UVB phototherapy of psoriasis. The TL01 emits radiation in a narrow band around 311-312 nm. Tumours developed on all animals. The dose-response relationship had practically the same shape as that found in a similar experiment with Westinghouse FS40 sunlamps; the tumour induction time appeared to be proportional to the daily dose to a power of -0.58. An additional experiment was performed with a TL01 from which the shorter wavelengths were filtered away. This reduced the carcinogenic effectiveness by a factor of 2.3. The potential of the filtered lamp for phototherapy of psoriasis is discussed.

Bath psoralen‐ultraviolet A therapy in atopic eczema

Aims To evaluate the efficacy of bath psoralen‐ultraviolet A (PUVA) therapy in severe cases of atopic dermatitis (AD) in adults using the extended Six Area, Six Sign Atopic Dermatitis (SASSAD) score.

Actinic reticuloid simulating sézary syndrome

SummaryA report is given on two male patients who showed all the main characteristics of Sézary syndrome (SS). When phototested, however, they proved to be extremely photosensitive, which suggested a diagnosis of actinic reticuloid (AR). This was supported by the predominance in blood and skin specimens of lymphoid cells with a suppressor/cytotoxic phenotype, the absence of clonal cell proliferation and a benign clinical course. Differential diagnostic problems of SS and erythrodermic AR are discussed.

Photodynamic therapy in a patient with Darier's disease

Patients with supernumerary nipples may also have associated anomalies. A wide range of concomitant associations has been described, mainly urogenital disorders, particularly in males. 6 Moreover, familiar antecedence of alcoholism as predisposing factor and the systematic urologic investigation in cases of polythelia/polymastia still remains controversial. In our case there was no urinary symptoms, but an accurated clinical evaluation in patients with supernumerary nipples is recommended. 1,2

The polymorphous light eruption-severity assessment score does not reliably predict the results of phototesting

Background  Polymorphous light eruption (PLE) is a very common photodermatosis in which patient history is highly specific. Phototesting is used to confirm the diagnosis and to determine the action spectrum and the severity of this disease. In daily practice and in research studies, it would be convenient to assess disease severity by patient history only.

Molecular dosimetry by flow cytometric detection of thymine dimers in mononuclear cells from extracorporally UV-irradiated blood

UV-induced DNA damage in mononuclear leucocytes can be quantified by flow cytometry of fluorescence from a labelled monoclonal antibody that specifically binds to thymine dimers (T<-->T): specific fluorescence is already detectable after exposures of 1-2 J m-2 of 254 nm radiation and shows a linear relationship with dose. The distribution of UV fluences over an irradiated volume can thus be ascertained by measuring the UV-induced T<-->T loads of the individual cells from that volume. After irradiation of mononuclear cells in a phosphate buffer solution in a Petri dish, most cells showed a similar intensity of specific T<-->T fluorescence, forming a single sharp peak in the fluorescence histogram. This signifies an even distribution of fluences over the cells. It was noticed, however, that a variable minor fraction of mononuclear cells (usually less than 10%) could be resistant to immunostaining; this fraction was rejected from the calculation of the specific fluorescence. The flow cytometric technique was also applied to blood cells exposed in an ISOLDA device, which is in use in Russian clinics for UV irradiation of whole blood for therapeutical purposes. Only a small fraction of mononuclear cells in a sample of whole blood treated in ISOLDA acquired a detectable T<-->T load after exposure to lamps which emit predominantly either UVC or UVB light ((3.6 +/- 1.0)% and (1.8 +/- 0.4)% of all analysed cells respectively). This small fraction had received a large variation in fluences, resulting in differences in nuclear T<-->T loads by a factor of 200.(ABSTRACT TRUNCATED AT 250 WORDS)