Real-life experience in the treatment of solar urticaria: retrospective cohort study

[Solar urticaria and polymorphous light eruption]

Solar urticaria is a rare idiopathic photodermatosis. According to the current knowledge its pathogenesis is most likely based on an allergic type I reaction to an autoantigen activated by ultraviolet (UV) radiation or visible light. As many of the patients suffer from severe forms of the disease, it may therefore severely impair the quality of life of those affected. In contrast, polymorphous light eruption is a very common disease, which, according to the current data, can be interpreted as a type IV allergic reaction to a photoallergen induced by UV radiation. As the skin lesions heal despite continued sun exposure, the patients' quality of life is generally not significantly impaired. These two clinically and pathogenetically very different light dermatoses have shared diagnostics by means of light provocation and an important therapeutic option (light hardening). Herein, we present an overview of the clinical picture, pathogenesis, diagnosis and available treatment options for the above-mentioned diseases.

Solar urticaria: clinical characteristics, treatment effectiveness, long-term prognosis, and QOL status in 29 patients

Introduction

Solar urticaria (SU), a relatively rare skin inflammatory and photosensitivity disease, is often resistant to standard urticaria treatment. Quality of life (QOL) among SU patients has not been extensively explored. This study was performed to clarify the clinical features and effectiveness of therapies (e.g., hardening therapy) for SU and to determine QOL among SU patients.

Methods

The authors examined the characteristics, treatments, and QOL statuses of 29 Japanese SU patients using medical records and a questionnaire approach.

Results

Among 29 patients, H1 antihistamine therapy (H1) was effective in 22 (75.8%) patients. H2 antihistamine therapy (H2) was effective in three of seven (42.9%) patients. Ultraviolet radiation A (UVA) hardening therapy was effective in eight of nine (88.9%) patients. Visible light (VL) hardening therapy was ineffective in three of three patients. In one patient who underwent both UVA and VL hardening therapy, only UVA hardening therapy was effective. In the questionnaire, 18 patients (90%) reported some improvement compared with disease onset (four had complete remission, six had completed treatment although mild symptoms persisted, and eight were receiving treatment with moderate symptoms), whereas two patients reported exacerbation. Patients in complete remission had a mean disease duration of 4 years, whereas patients not in remission had a mean disease duration of 8.8 years. The mean Dermatology Life Quality Index (DLQI) score for the current status was 7.4. There was a correlation between DLQI and symptom/treatment status. However, neither DLQI and action spectra nor DLQI and treatments exhibited significant differences.

Discussion

The questionnaire revealed current QOL status and long-term prognosis in SU patients. Compared with disease onset, most patients showed improvement when assessed for this study. Both H1 and H2 should be attempted for all SU patients. UVA hardening therapy may be an option for SU patients with an action spectrum that includes UVA.

Solar Urticaria: An Ambispective Study in a Long-term Follow-up Cohort with Emphasis on Therapeutic Predictors and Outcomes

Solar urticaria is a rare photodermatosis with several unknown pathogenic, clinical and therapeutic aspects. This study analysed the clinical and therapeutic features of a long-term follow-up solar urticaria cohort, with a focus on omalizumab management and outcomes, and characterized omalizumab response with the use of the high-affinity immunoglobulin E (IgE) receptor (FcεRI) and the Urticaria Control Test. An observational, unicentric, ambispective study was conducted from 2007 to 2023. Solar urticaria was diagnosed in 41 patients with a median follow-up of 60 months. Thirteen patients were prescribed omalizumab, with a median treatment time of 48 months. A significant decrease in FcεRI baseline levels and subsequent median increase in Urticaria Control Test was evidenced after omalizumab prescription in all patients. Drug survival at 48 months was at 88.9%. Omalizumab stepping-down protocol led to sustained omalizumab discontinuation in only 1 patient. Median basal Urticaria Control Test was lower (p < 0.01) in patients who were prescribed omalizumab and in patients without remission. This study contributes to our knowledge of omalizumab outcomes in real-life clinical practice and highlights the pathogenic importance of IgE-mediated pathways in solar urticaria, where FcεRI emerges as a possible biomarker of omalizumab response.

Comparison between chronic spontaneous urticaria and chronic induced urticaria on the efficacy of omalizumab treatment: A systematic review and meta-analysis

This meta-analysis aimed to assess the efficacy of omalizumab in the treatment of refractory-to-antihistamines chronic induced urticaria (CIndU) in comparison with that of refractory-to-antihistamines chronic spontaneous urticaria (CSU). We retrieved interventional studies and observational studies on omalizumab efficacy to CIndU patients and efficacy comparison between CSU and CIndU both refractory to H1-antihistamines in electronic databases (accessed till May 2022). The odd ratio (OR) and 95% confidence interval (CI) was calculated with a random-effect model in this meta-analysis. The majority of patients with different CIndU subtypes gained complete or partial response and good safety after omalizumab treatment. A total of five studies with 355 CSU patients and 103 CIndU patients were included for the meta-analysis. There was no significant difference in the efficacy of omalizumab in the treatment of CSU and CIndU (OR -0.83, 95% CI [0.84, 2.21], P > 0.05). Based on the validity of omalizumab in the treatment of various CIndU subtypes and non-differential efficacy between CSU and CIndU, it is reasonable to list omalizumab as a third-line treatment of refractory CIndU.

Isolated solar angioedema: A systematic review of the literature

Solar urticaria is a well-recognized photodermatosis, sometimes accompanied by angioedema. However, isolated solar angioedema (ISA) is a rare and unrecognized entity. The purpose of our work was to systematically review the available data on ISA. Therefore, a systematic review of studies evaluating ISA was performed. Additionally, a case of a 21-years-old patient from our photodermatosis service is presented. The search yielded 421 publications, with 3 eligible for review. Together with our case, 5 cases were included overall. All patients were female. Four out of 5 patients first experienced ISA at childhood or early adulthood (age range 6-22 years). UVA photoprovocation was positive in the 3 out of the 4 patients who were tested. Improvement was noted following NB-UVB hardening (2 out of 5 patients) or a short course of oral prednisone (3 out of 5 patients) combined with regular sunscreen application. To conclude, ISA is an extremely rare entity, although it may be underdiagnosed due to lack of awareness. The clinician must consider ISA in the differential diagnosis of angioedema since it can have a detrimental effect on quality of life. Besides sun avoidance, there is no consensus regarding treatment.