Solar urticaria involves rapid mast cell STAT3 activation and neutrophil recruitment, with FcεRI as an upstream regulator.

BACKGROUND: Solar urticaria is a rare photodermatosis characterized by rapid-onset sunlight-induced urticaria, but its pathophysiology is not well understood. OBJECTIVE: We sought to define cutaneous cellular and molecular events in the evolution of solar urticaria following its initiation by solar-simulated UV radiation (SSR) and compare with healthy controls (HC). METHODS: Cutaneous biopsy specimens were taken from unexposed skin and skin exposed to a single low (physiologic) dose of SSR at 30 minutes, 3 hours, and 24 hours after exposure in 6 patients with solar urticaria and 6 HC. Biopsy specimens were assessed by immunohistochemistry and bulk RNA-sequencing analysis. RESULTS: In solar urticaria specimens, there was enrichment of several innate immune pathways, with striking early involvement of neutrophils, which was not observed in HC. Multiple proinflammatory cytokine and chemokine genes were upregulated (including IL20, IL6, and CXCL8) or identified as upstream regulators (including TNF, IL-1ß, and IFN-γ). IgE and FcεRI were identified as upstream regulators, and phosphorylated signal transducer and activator of transcription 3 expression in mast cells was increased in solar urticaria at 30 minutes and 3 hours after SSR exposure, suggesting a mechanism of mast cell activation. Clinical resolution of solar urticaria by 24 hours mirrored resolution of inflammatory gene signature profiles. Comparison with available datasets of chronic spontaneous urticaria showed transcriptomic similarities relating to immune activation, but several transcripts were identified solely in solar urticaria, including CXCL8 and CSF2/3. CONCLUSIONS: Solar urticaria is characterized by rapid signal transducer and activator of transcription 3 activation in mast cells and involvement of multiple chemotactic and innate inflammatory pathways, with FcεRI engagement indicated as an early event.

The Immunogenetics of Photodermatoses.

Photodermatosis is an abnormal skin inflammatory reaction to light. The major classifications of photodermatoses are idiopathic photodermatoses, photodermatoses due to exogenous or endogenous agents, photo-exacerbated dermatoses, and photosensitive genodermatoses. In this chapter, we focus on idiopathic photodermatoses and drug-related photodermatoses and emphasize on the epidemiology and immunogenetic backgrounds. Idiopathic photodermatoses, a spectrum of diseases with abnormal responses to ultraviolet radiation (UVR), include polymorphous light eruption, actinic prurigo, hydroa vacciniforme, chronic actinic dermatitis, and solar urticaria. Young people are more susceptible to most idiopathic photodermatoses except for chronic actinic dermatitis. Interestingly, idiopathic photodermatoses exhibit different characteristics between Caucasians and Asians. For example, the average age of Asian actinic prurigo patients is older than that of Caucasians in which genetic backgrounds or Fitzpatrick skin type might play a role. Drug-induced photodermatoses can be classified into phototoxic and photoallergic drug reactions. Certain drug-induced photodermatoses may mimic other dermatoses. For instance, drug-induced lupus erythematosus (LE) should be considered if an old man is diagnosed with LE but had a poor response to standard treatments.

Comparison of racial distribution of photodermatoses in USA academic dermatology clinics: A multicenter retrospective analysis of 1080 patients over a 10-year period.

BACKGROUND: Previous studies at single academic institutions have identified variations in the prevalence of photodermatoses among racial groups. The purpose of the study was to compare the distribution of photodermatoses between Whites and Blacks at four academic medical centers in the USA. METHODS: A retrospective chart review was performed at four institutions' general dermatology clinics using diagnoses consistent with the International Classification of Disease (ICD), Ninth and Tenth Revisions, codes related to photodermatoses between August 2006 and August 2016. A total of 9736 charts were manually reviewed and classified. Analyses were performed analyzing the frequency of photodermatoses between Whites and Blacks in the pooled data. RESULTS: There were 1,080 patients with photodermatoses identified. Statistically significant differences in the frequency of photodermatoses between Whites and Blacks were identified for polymorphous light eruption (more common in Blacks), photoallergic contact dermatitis, phototoxic drug eruption, phytophotodermatitis, porphyria, and solar urticaria (more common in Whites). The most commonly diagnosed photodermatoses were polymorphous light eruption (total 672), and photodermatitis not otherwise specified (total 189). CONCLUSION: Our study demonstrated significantly higher proportions of polymorphous light eruption in Blacks, and higher proportions of photoallergic contact dermatitis, phototoxic drug eruptions, phytophotodermatitis, porphyrias, and solar urticaria in Whites.

Successful treatment of solar urticaria with UVA1 hardening in three patients.

Solar urticaria (SU) is an uncommon photodermatosis that presents with sensitivity to ultraviolet (UV) or visible light which triggers urticarial lesions. Treatment of SU is a challenge and usually involves antihistamines and photoprotection as a first-line treatment. Phototherapy regimens are recommended if these first-line treatments fail to control the disease. Induction of tolerance by phototherapy (UV hardening) has been commonly described as a treatment modality. UVA1 has deeper penetration to the dermis than UVA or NB-UVB; its use in SU has not been previously reported. We present 3 patients with SU who were successfully treated with UVA1.

Solar urticaria - An Australian case series of 83 patients.

Solar urticaria (SU) is a rare form of urticaria with a pathogenesis that is poorly understood. It affects all skin types, can be difficult to diagnose, and is challenging to manage effectively. We conducted a retrospective review of patients with SU in our institution. A total of 83 patients (56 females) were identified as having SU. The mean age was 32 years (7-74) at first development of symptoms/signs of SU. Pruritus was the most common symptom reported (79%). Of the 60 patients who underwent monochromator testing at least once, 35 had SU confirmed with most reacting to visible light and UVA, or to UVA alone. Antihistamines and sun avoidance remain the mainstay treatment for SU but other treatments, including omalizumab, are of potential interest in treating patients with recalcitrant SU. The characterisation of this large case series of patients may help dermatologists recognise and manage this rare disorder appropriately.

Clinical and photobiological response in eight patients with solar urticaria under treatment with omalizumab, and review of the literature.

BACKGROUND: Solar urticaria (SU) is a rare photodermatosis. Treatment is challenging, and outcomes are often disappointing. Omalizumab is an anti-IgE, currently approved for treatment of chronic spontaneous urticaria. We sought to evaluate therapy with omalizumab in refractory SU and describe predictive factors for response. MATERIALS/METHODS: Patients with refractory SU under treatment with omalizumab were included in this study. Clinical outcome was evaluated using the Urticaria Activity Score 7 (UAS7), Dermatology Life Quality Index (DLQI) and Pruritus Visual Analogue Scale (VAS). Complete clinical response (CCR) was defined as having an UAS7 = 0, DLQI <6 and VAS = 0. Phototesting was performed and compared to baseline. We performed a PubMed search to identify reported cases of SU in adults treated with omalizumab, analysing their characteristics in order to predict response to omalizumab. RESULTS: Eight patients were included. Median age was 45.5 years (range, 23-64). Light spectrum most commonly implicated was UV-A. Clinical outcomes: 89% (7/8) achieved CCR with omalizumab. Phototesting was normal in 42.8% (3/7) of them. In our review, we identified 38 patients (including the current case series), and 68.4% showed favourable outcomes with omalizumab. Median time since onset of SU was lower in responders. CONCLUSIONS: Omalizumab can be an effective treatment in refractory SU.

Solar urticaria in 145 patients: Assessment of action spectra and impact on quality of life in adults and children.

BACKGROUND: Solar urticaria (SU) is a rare chronic inducible urticaria triggered via uncharacterized chromophores. We detail responses of a large patient series to monochromator phototesting and broadband ultraviolet radiation (UVR); relationship to life quality is explored. METHODS: Retrospective review of all SU patients undergoing standardized diagnostic photoinvestigation at a specialist centre during 2000-2016. From 2011, patients completed dermatology life quality index (DLQI) questionnaires for the past week and year. RESULTS: In 145 patients (mean: 35.8, range: 3-69 years; 18 aged <18 years; 100 female), combined phototesting with broadband UVR and monochromator sources successfully provoked 74.5% patients, with 65.6% provoked by broadband UVR alone and 57.9% by monochromated radiation alone. The narrow wavebands most frequently eliciting wheal and flare response were between 370 and 400 nm, with 25% patients at 300 ± 5 nm, 53.6% at 320 ± 10 nm, 66.7% at 330 ± 10 nm, 77.4% at 350 ± 20 nm, 83.3% at 370 ± 20 nm, 86.9% at 400 ± 20 nm, 44% at 500 ± 20 nm and 17.8% at 600 ± 20 nm. In 62 patients, the DLQI revealed 56.1% had very to extremely large impact in the past week (all patients: mean score: 11.1, range: 0-29) rising to 69.8% for the past year (12.5, 0-30); adults and children were similarly affected. Patients with positive photoprovocation had higher DLQI score than those who were negative (DLQI for past week: mean: 12.6 ± SEM 1.1 vs 4.6 ± 1.4, P < .01). CONCLUSION: SU is predominantly provoked by longer UVA-shorter visible radiation, which penetrates window-glass and where sunscreens are less effective; impact on life quality is considerable. Photoprotective agents effective against this spectrum are needed.

Afamelanotide in the Treatment of Dermatologic Disease

Afamelanotide, an α-melanocyte stimulating hormone analogue, has become an emerging therapeutic option for a variety of skin conditions previously refractory to other treatments. Its efficacy has been demonstrated in several dermatologic conditions, including erythropoietic protoporphyria (EPP), solar urticaria, polymorphic light eruption (PMLE), vitiligo, acne, and Hailey-Hailey disease. Its relatively low risk side effect profile makes it an attractive treatment option and also paves the way for innovative use in other disorders.

Solar urticaria: Epidemiology and clinical phenotypes in a Spanish series of 224 patients. / Urticaria solar. Epidemiología y fenotipos clínicos en una serie española de 224 pacientes.

BACKGROUND: Solar urticaria is a chronic inducible urticaria also classified as an idiopathic dermatosis. The objective of this paper is to define the phenotypic characteristics of solar urticaria and to evaluate its incidence. MATERIAL AND METHOD: This was a retrospective multicenter study in which data were gathered on the epidemiology and clinical, photobiologic, laboratory, and therapeutic characteristics of solar urticaria. RESULTS: A total of 224 patients (141 women and 83 men) were included from 9 photobiology units. The mean age of the patients was 37.9 years (range, 3-73 years). A history of atopy was detected in 26.7%, and the most common presentation was allergic rhinitis (16.5%). Clinical signs were limited to sun-exposed areas in 75.9% of patients. The light spectrum most commonly implicated was visible light only (31.7%), and in 21% of cases it was only possible to trigger solar urticaria with natural light. The treatments most widely used by photobiology experts were oral antihistamines (65.46%), followed by different forms of phototherapy (34%). Complete resolution was observed most often in patients with solar urticaria triggered exclusively by visible or natural light, with statistically significant differences with respect to other wavelengths (P<.05). No increase in the annual incidence of solar urticaria was observed. CONCLUSIONS: We have presented the largest series of solar urticaria published to date. The epidemiological, clinical, and photobiologic findings confirm previously reported data, although there was a particularly high rate of negative phototests in our series. Reactivity exclusively to visible or natural light was associated with a higher probability of resolution. No increasing trend was observed in the annual incidence.

Response to Omalizumab in Solar Urticaria: Report of 3 Cases. / Respuesta a omalizumab en 3 casos de urticaria solar.

We report 3 cases of solar urticaria in which there was no response or limited response to first-line treatments with high-dose H1 antihistamines or phototherapy. The patients were then treated with omalizumab. Symptoms improved in 2 patients, whose tolerance to sunlight increased considerably; quality of life clearly improved for 1 of these patients. The third experienced no improvement and developed a mild local reaction to the injected medication. We conclude that omalizumab may offer a potentially safe, useful alternative for patients with solar urticaria who do not respond to conventional therapy.

Omalizumab in the Treatment of Chronic Inducible Urticaria. / Omalizumab en el tratamiento de la urticaria crónica inducible.

Omalizumab is a recombinant humanized monoclonal antibody that inhibits immunoglobulin E. It has been approved for the treatment of severe asthma and chronic spontaneous urticaria refractory to other treatments. Its use in the management of chronic inducible urticaria (a type triggered by certain stimuli) is still considered off-label, although this use has been discussed in some consensus papers. This review brings together case reports and case series describing the use of omalizumab to treat chronic inducible urticaria. We analyze the most important aspects of the cases and the outcomes reported. The results seem to position omalizumab as a potentially effective, safe treatment alternative in some cases of chronic inducible urticaria.

Infrared radiation increases skin damage induced by other wavelengths in solar urticaria.

BACKGROUND: Photodermatoses are typically investigated by analyzing the individual or combined effects of ultraviolet A (UVA), ultraviolet B (UVB), and visible light using light sources that simulate portions of the solar spectrum. Infrared radiation (IRR), however, accounts for 53% of incident solar radiation, but its effects are not taken into account in standard phototest protocols. AIMS: The aim was to analyze the effects of IRR, alone and combined with UVA and visible light on solar urticaria lesions, with a distinction between infrared A (IRA) and infrared B (IRB). METHODS: We performed standard phototests with UVA and visible light in four patients with solar urticaria and also tested the effects after blocking IRB with a water filter. To analyze the direct effect of IRR, we performed phototests with IRA and IRB. RESULTS: Initial standard phototests that were all positive found the induction of erythema and whealing, while when IRR was blocked from the UVA and visible light sources, three of the patients developed no lesions, while the fourth developed a very small wheal. CONCLUSION: These results suggest that IRR has the potential to produce and exacerbate lesions caused by other types of radiation. Consideration of these effects during phototesting could help prevent diagnostic errors.

Treatment of solar urticaria using antihistamine and leukotriene receptor antagonist combinations tailored to disease severity.

BACKGROUND: Solar urticarial (SU) is characterized by erythema, whealing, and/or pruritus occurring minutes after sun exposure. Treatment is difficult and often unsatisfactory. OBJECTIVES: To determine the action spectra and minimal urticaria dose (MUD) and to tailor a treatment regimen graded according to disease severity in a series of patients with SU. PATIENTS AND METHODS: Eleven patients (seven females, four males, age range: 5-60 years) with a clinical history suggestive of SU, verified by photo-provocation tests to ultraviolet A (UVA), visible light, and/or UVB, were treated with various combinations of antihistamines and leukotriene receptor antagonist. RESULTS: All patients were sensitive to visible light (median MUD 50 J/cm(2)). Three patients were sensitive to UVA (median MUD 3.75 J/cm(2)), and one patient was sensitive to UVB (MUD of 0.03 J/cm(2)). Two patients experienced a spontaneous remission without treatment. One patient declined treatment. The remaining eight patients were managed by a combination of antihistamines (desloratidine, fexofenadine, cetirizine HCl) and a leukotriene receptor antagonist (montelukast). Seven of the 8 patients experienced a sustained remission of symptoms and signs following treatment. CONCLUSIONS: Photoprovocation for SU with determination of action spectra and MUD enables specifically tailored treatment regimens consisting of combinations of antihistamines and leukotriene receptor antagonist.

Severe and refractory solar urticaria treated with intravenous immunoglobulins: a phase II multicenter study.

BACKGROUND: Retrospective data have suggested the effectiveness of intravenous immunoglobulins (IVIG) for solar urticaria (SU). OBJECTIVE: We sought to prospectively assess the efficacy of IVIG for SU. METHODS: We conducted a multicentric phase II study to test the efficacy of a single course of IVIG (2 g/kg) in patients with severe and refractory SU. The primary outcome was remission of SU on phototesting at 12 weeks after IVIG treatment. Secondary objectives included clinical remission, improved quality of life, and 50% improvement in disease intensity as measured on a visual analog scale. RESULTS: Of the 9 patients who received IVIG injection, 2 showed remission of SU on phototesting, corresponding to a response rate of 22.2% (95% confidence interval 2.8%-60.0%). In all, 6 patients (67%) showed at least 1 response criterion after 4 weeks and 5 (56%) after 12 weeks. Response was maintained after 24 weeks for 2 patients and after 48 weeks for 1 patient. About half of the patients (56%) had moderate to severe headache. LIMITATIONS: Lack of control arm and small number of patients are limitations. CONCLUSION: A single course of IVIG appears insufficient to obtain prolonged significant control of SU; future evaluation of different schedules of IVIG administration is warranted.

Comparison of photodermatoses in African-Americans and Caucasians: a follow-up study.

BACKGROUND/PURPOSE: Only a few studies have compared frequencies of photodermatoses among different races and skin types. This is an extension of a study performed by Kerr and Lim and evaluates the frequency of photodermatoses in African-Americans compared with Caucasians in the same institution during an 8-year period. METHODS: Retrospective chart review was performed, including dermatology clinic charts from October 2004 to August 2012 with International Classification of Diseases, Ninth Revision diagnostic codes related to photodermatoses. RESULTS: We identified 229 patients with photodermatoses. Of these, 138 (46.6%) were African-American and 63 (42.2%) were Caucasian. Statistically significant differences in the distribution of photodermatoses in African-Americans and Caucasians, respectively, were as follows: phototoxic drug eruption (0.7% and 15.9%, P < 0.0001), phytophotodermatitis (0% and 6.3%, P = 0.009), polymorphous light eruption (PMLE) (86.2% and 54%, P < 0.0001) and porphyrias (0% and 7.9%, P = 0.003). CONCLUSION: Combined with data from Kerr and Lim, this is the largest study of photodermatoses in African-Americans to date. Congruent to former studies, photodermatoses do occur regularly in dark-skinned individuals. Overall, the frequency of photodermatoses in African-Americans and Caucasians are similar; however, PMLE occurs more commonly in African-Americans, and porphyias and phototoxicity occur more commonly in Caucasians.

Successful serial plasmapheresis for solar urticaria, a case report and literature review.

BACKGROUND/PURPOSE: Amidst the emergence of new therapeutic options, traditional therapeutic plasmapheresis (TPE) used in diseases involving a toxic substance in the plasma, remains a viable alternative for cases of recalcitrant solar urticaria (SU). We emphasize the importance of documenting successful experience with repeated plasmapheresis to increase awareness amongst physicians and dermatologists regarding this effective treatment option. MATERIAL AND METHOD: We reported a case of recalcitrant SU that had not responded to a combination of H1-antihistamines, immunosuppressants, omalizumab and intravenous immunoglobulin. We introduced serial TPE, which involved two consecutive days of procedures for each course was introduced. We detailed the regimen and highlighted the clinical and objective benefits observed with multiple treatments. Additionally, we compared this to other plasmapheresis regimens and their treatment responses previously reported for solar urticaria. RESULTS: Our patient underwent serial TPE, totaling 42 procedures over five years. Following the last TPE session, phototesting showed a sustained prolongation of minimal urticating doses (MUDS), which exceeded the maximum tested doses across nearly all ultraviolet (UV) and visible light ranges, with the exception of the two short ultraviolet B (UVB) wavelengths. MUDs increased to 25 from 6 mj/cm2 at 307.5± 5nm, and to 500 from 15 mj/cm2 at 320 ± 10nm, before the initial TPE. In our review, we included five articles covering eight SU patients who received TPE. Of these, the five patients with positive intradermal tests responded particularly well immediately after treatment. However, the condition relapsed within two weeks in one patient and within two months in another. In contrast, the other three patients with negative intradermal tests, showed no significant benefits from the treatment. No serious side effects from TPE were reported amongst the patients. CONCLUSIONS: This review underscores the efficacy of serial plasmapheresis procedures in treating refractory cases of SU, high3lighting the robust results observed.

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.

Chronic Inducible Urticaria.

Chronic inducible urticaria (CIndU) is characterized by the appearance of hives (urticaria) and/or angioedema in response to specific triggers or stimuli. For accurate diagnosis, anamnesis-driven specific, and if available, standardized trigger testings, as well as patient reported outcomes, should be applied. The currently recommended treatment algorithm is the same as for chronic spontaneous urticaria but is largely off-label for CIndU. New, and possibly more disease-specific, treatment options are needed for CIndU patients, who are often severely impacted by their disease. Several clinical trials are currently ongoing.