Sweet's syndrome triggered by ultraviolet light.

Sweet's syndrome is a neutrophilic dermatosis associated with many different underlying conditions but only rarely is it triggered by environmental factors such as ultraviolet (UV) exposure. We present two cases of photoinduced Sweet syndrome. Our first patient, who was taking hydrochlorothiazide, presented photodistributed lesions, pathological phototest and neutrophilic dermatosis histopathology. The phototest normalized after drug withdrawal, suggesting that both UV light and hydrochlorothiazide were necessary to cause the lesions. Our second case presented lesions clearly induced by UV light and histologically consistent with Sweet's syndrome. The MED was decreased and the lesions were reproduced with nbUVB, suggesting the diagnosis of photoinduced Sweet's syndrome. In conclusion, we report a case of neutrophilic dermatosis induced by hydrochlorothiazide and UV light and a case of photoinduced Sweet's syndrome with reproduction of the lesions after nbUVB. Both patients had a pathologic photobiological study. Our report emphasizes the need to perform phototests in patients with photodistributed Sweet's syndrome.

Is it Useful to Calculate Minimal Erythema Dose Before Narrowband UV-B Phototherapy? / ¿Es útil la determinación de la dosis eritematógena mínima previa a la fototerapia ultravioleta B de banda estrecha?

INTRODUCTION AND OBJECTIVES: The starting dose for narrowband UV-B phototherapy is determined by a patient's skin phototype or minimal erythema dose (MED). Calculation of MED identifies patients with unsuspected photosensitivity. The aim of this study was to investigate the influence of factors such as concomitant use of photosensitizing agents, diagnosis, and combination with acitretin in patients with psoriasis on the frequency and severity of adverse effects in patients with a low MED to narrowband UV-B phototherapy. MATERIAL AND METHODS: We undertook a retrospective observational cohort study between February 1, 2009 and March 31, 2015. MED values were classified as normal or low. RESULTS: In total, 302 patients with different skin conditions started narrowband UV-B phototherapy at a dose determined by their MED. No differences were found between patients with a low MED and those with a normal MED for number of drugs taken (P=.071) or use of photosensitizing agents (P=0.806). Following adjustment for age, sex, and phototype, the multivariate analysis showed that psoriasis exerted a protective effect against a low MED (OR=0.31 [95% CI, 0.16-0.58]). No significant risk of erythema or pruritus was detected in patients with a low MED (OR=1.68; 95% CI, 0.91-3.29 and OR=2.04; 95% CI, 0.99-4.22, respectively). CONCLUSIONS: Psoriasis protects against a low MED. Although erythema and pruritus were more common in patients with a low MED, the differences were not significant.

Determination of minimal erythema dose and anomalous reactions to UVA radiation by skin phototype.

BACKGROUND: Phototesting is a technique that assesses the skin's sensitivity to UV radiation by determining the smallest dose of radiation capable of inducing erythema (minimal erythema dose [MED]) and anomalous responses to UV-A radiation. No phototesting protocol guidelines have been published to date. METHODOLOGY: This was a multicenter prospective cohort study in which 232 healthy volunteers were recruited at 9 hospitals. Phototests were carried out with solar simulators or fluorescent broadband UV-B lamps. Each individual received a total of 5 or 6 incremental doses of erythemal radiation and 4 doses of UV-A radiation. The results were read at 24hours. RESULTS: At hospitals where solar simulators were used, the mean (SD) MED values were 23 (8), 28 (4), 35 (4), and 51 (6) mJ/cm(2) for skin phototypes i to iv, respectively. At hospitals where broadband UV-B lamps were used, these values were 28 (5), 32 (3), and 34 (5) mJ/cm(2) for phototypes ii to iv, respectively. MED values lower than 7, 19, 27, and 38 mJ/cm(2) obtained with solar simulators were considered to indicate a pathologic response for phototypes I to IV, respectively. MED values lower than 18, 24, and 24mJ/cm(2) obtained with broadband UV-B lamps were considered to indicate a pathologic response for phototypes ii to iv, respectively. No anomalous responses were observed at UV-A radiation doses of up to 20J/cm(2). CONCLUSIONS: Results were homogeneous across centers, making it possible to standardize diagnostic phototesting for the various skin phototypes and establish threshold doses that define anomalous responses to UV radiation.

Photodistributed erythema multiforme.

Although the existence of photodistributed erythema multiforme has been recognized for years, few cases have been described to date. It is an uncommon, and probably underdiagnosed, skin disorder that can affect individuals of both sexes and all ages. It has been associated with drugs, reactivation of herpes simplex virus infection, and polymorphous light eruption. A diagnosis is made on the basis of history, physical examination, histology, and phototesting. The condition runs a benign, self-limiting course but patients may experience outbreaks for several years if the causative agent is not eliminated. It is treated symptomatically and patients are advised to avoid triggers and excessive sun exposure.

[Therapeutic effectiveness of psoralen-UV-A bath therapy in psoriasis]. / Eficacia terapéutica del baño-PUVA en psoriasis.

INTRODUCTION: The use of psoralen baths with long-wave UV radiation, known as PUVA bath therapy, is useful in the treatment of psoriasis. The therapy is not associated with systemic adverse effects and the dose of UV-A radiation administered is lower. The objectives of this study aimed to identify the variables that influence the effectiveness of PUVA bath therapy and the duration of remission, as well as to determine factors that predict relapse. It also aimed to assess the effectiveness of a protocol using the minimal phototoxic dose and to compare two concentrations of 8-methoxypsoralen. PATIENTS AND METHODS: Two hundred nine patients with moderate-severe plaque psoriasis attended between 1994 and 2000 were included in the study. The characteristics and therapeutic outcomes of the sample were recorded. Survival curves were plotted for the disease-free interval after a good response to treatment. A proportional hazard model was used to assess the factors that influence the duration of remission. RESULTS: Therapeutic outcomes were better in patients with greater photosensitivity (p = 0.03). Application of the minimal phototoxic dose protocol was not associated with greater phototoxicity during treatment. The median duration of remission was 7 months. Those patients who had previously undergone oral PUVA therapy and those who did not achieve a substantial reduction in the psoriasis area and severity index (PASI) score were at greater risk of relapse. CONCLUSIONS: A lower final PASI extended the lesion-free period.

[Consensus document on bath-PUVA therapy. The Spanish Photobiology Group of the Spanish Academy of Dermatology and Venereology]. / Documento de consenso sobre la modalidad terapéutica del baño-PUVA. Grupo Español de Fotobiología de la Academia Española de Dermatología and Venereología.

Bath PUVA is a variant of phototherapy as efficacious as oral PUVA therapy that avoids many of the adverse effects associated to this treatment. Nevertheless, the special features and the specialized equipment required for its employment have limited its application in the dermatologic clinics of our country. Following the trend initiated after the publication of the consensus document on oral PUVA therapy and narrow band (NB) UVB therapy, the Spanish Photobiology Group from the Spanish Academy of Dermatology and Venereology has developed a therapeutic guideline for bath PUVA therapy based on the literature review and the experience of its members. The document aims to be a practical reference guide for those dermatological centres that include phototherapy among their services. It reviews the concept and indications of this type of treatment and proposes recommendations concerning therapeutic procedures, drug associations of interest and prophylaxis and management of adverse effects.