Phototesting

Abstract: Photochemotherapy is a recently developed approach to the treatment of psoriasis (Parrish et al., 1974) which may have initiated a new era in photomedicine. It is based on the interaction of longwave ultraviolet light (UVA) and a systemically administered photoactive compound, 8-methoxypsoraIen, within the skin; hence the designation PUVA (PUVA = 8-methoxy-Psoralen plus UVA) (WolfFer a/., 1976). As the penetration of UVA is restricted to the superficial layers of the skin and as the photoactivadon of 8-methoxypsoralen occurs only under the influence of these wave-lengths ('365 nm), PUVA represents a successful attempt to localize systemic chemotherapy to a diseased organ, the skin, sparing other tissues from cytotoxic effects (Parrish et al., 1974; Wolff er al., 1975b, 1976). The dramatic effectiveness of this treatment, both in clearing psoriatic lesions and maintaining patients in a state of remission, has been demonstrated in several studies (Parrish ei ai, 1974; Wolfl' al., 1975a, b, 1976). The rationale of PUVA therapy is to bring psoriasis into remission by repeated, controlled photosensitization reactions which are monitored to remain within a therapeutically desired range. Since phototoxic erythema is a limiting factor, careful attention to dosimetry is essential and it is therefore the dosimetry system which is a key to both the effectiveness and safety of PUVA. The following account outlines and discusses criteria for dosimetry that have proved useful in 230 patients with severe, generalized psoriasis.

Abstract: Photo-induced drug eruptions are cutaneous adverse events due to exposure to a drug and either ultraviolet or visible radiation. Based on their pathogenesis, they can be classified as phototoxic or photoallergic drug eruptions, although in many cases it is not possible to determine whether a particular eruption is due to a phototoxic or photoallergic mechanism. In this review, the diagnosis, prevention and management of drug-induced photosensitivity are discussed. Diagnosis is based primarily on the history of drug intake and the clinical appearance of the eruption, primarily affecting sun-exposed areas of the skin. Phototesting and photopatch testing can be useful adjuncts in making a diagnosis. The mainstay of management is prevention, including informing patients of the possibility of increased sun sensitivity and the use of sun protective measures. However, once the eruption has occurred, it may be necessary to discontinue the culprit medication and treat the eruption with a potent topical corticosteroid. Drugs that have been implicated in causing photosensitive eruptions are reviewed. Tetracycline, doxycycline, nalidixic acid, voriconazole, amiodarone, hydrochlorothiazide, naproxen, piroxicam, chlorpromazine and thioridazine are among the most commonly implicated medications. We review the medical literature regarding evidence for the culpability of each drug, including the results of phototesting, photopatch testing and rechallenge testing.

Abstract: SummaryBackground There is a clear relationship between ultraviolet (UV) radiation (UVR) and the clinical manifestations of patients with lupus erythematosus (LE). Cutaneous lesions are induced or exacerbated by exposure to UVR. Of patients with LE, 24–83% are reported to be photosensitive to UVR. LE tumidus appears to be the most photosensitive subtype of LE, followed by subacute cutaneous LE (SCLE). In general, the history of patients with LE correlates poorly with the presence or absence of photosensitivity, due to a delayed time interval between UV exposure and exacerbation of skin lesions. Phototesting using artificial UVR and visible light is a reliable way of diagnosing photosensitivity. Objectives To investigate the photoreactivity of patients with various subtypes of LE using an individualized phototest protocol. The results of phototests were correlated with the history of photosensitivity, the subtype of LE, the presence of autoantibodies and the use of anti-inflammatory medication by these patients. Methods Phototesting with UVA, UVB and visible light was performed in 100 patients with LE. The diagnosis of LE was established both on clinical examination and skin histology. Serological studies were also performed in all patients. The phototests were performed on large skin areas of the forearm or trunk; the first dose was twice the minimal erythema dose and the dosage was increased according to the individual reactions of the patients at the test sites. Follow-up of skin reactions at the test sites was performed for up to 2 months. Histological examination of the photoprovoked skin lesions was carried out in 57 patients. Results Of the 100 patients included (81 women and 19 men; mean age 41 years, range 17–79), 46 had chronic discoid LE, 30 SCLE and 24 systemic LE. An abnormal reaction to UVR and visible light was found in 93% of our patients with LE. No clinical or histological evidence at the phototest sites of polymorphic light eruption was found. There was no correlation between photosensitivity and LE subtype, presence of autoantibodies or medical history. Concomitant use of anti-inflammatory medication seemed to exert only minimal influence on the results of phototesting. Conclusions When using an extended phototesting protocol, almost all patients with LE in this study showed clinical and histological evidence of aberrant photosensitivity. Therefore, patients with LE should receive thorough advice and instruction on photoprotective measures, regardless of their history, LE subtype or presence of autoantibodies.

Abstract: Objective We sought to assess if the exclusive use of a broad-spectrum sunscreen can prevent skin lesions in patients with different subtypes of cutaneous lupus erythematosus (CLE) induced by ultraviolet (UV) irradiation under standardized conditions. Methods A total of 25 patients with a medical history of photosensitive CLE were included in this monocentric, randomized, vehicle-controlled, double-blind, intraindividual study. The test product and its vehicle were applied 15 minutes before UVA and UVB irradiation of uninvolved skin areas on the upper aspect of the back in a random order, and standardized phototesting was performed daily for 3 consecutive days. Results Characteristic skin lesions were induced by UVA and UVB irradiation in 16 patients with CLE in the untreated area, and 14 patients showed a positive test result in the vehicle-treated area. In contrast, no eruptions compatible with CLE were observed in the sunscreen-treated area in any of the 25 patients. This resulted in significant differences ( P P Limitations Data resulting from standardized experimental phototesting might not be transferable to a clinical setting. Conclusion These results indicate clearly that the use of a highly protective broad-spectrum sunscreen can prevent skin lesions in photosensitive patients with different subtypes of CLE.