Solar urticaria. A report of 25 cases and difficulties in phototesting

Overexposure to ultraviolet radiation in solar urticaria

A man in his 50s was diagnosed with solar urticaria following monochromated light testing that demonstrated exquisite photosensivity to ultraviolet (UV) A, UV B (UVB) and visible light.Treatment options for this photodermatosis are limited; UVB phototherapy is one modality that can be appropriate in some patients. This is administered at very low doses in a controlled environment to induce skin hardening.1 To self-treat his condition, the patient used a commercial sunbed on two occasions several days apart. He noted an immediate flare of solar urticaria after first use with associated dizziness. Following the second use, he felt generally unwell and was witnessed to lose consciousness and displayed jerky movements of his limbs while a passenger in a car. Investigations including a head MRI and an EEG were normal; an anoxic seizure caused by a flare of solar urticaria was later confirmed.Solar urticaria is a rare photodermatosis that is poorly understood and difficult to treat. The condition has a significant impact on the quality of life of patients. Severe cases can be associated with systemic symptoms that could be life-threatening.

Pathogenesis of solar urticaria: Classic perspectives and emerging concepts

Solar urticaria is a rare, immunologically mediated photodermatosis in which activation of cutaneous mast cells is triggered by specific wavelengths of solar electromagnetic radiation. This manifests clinically as the rapid development of cutaneous itch, erythema and wheal formation after several minutes of sun exposure. Disease mechanisms in solar urticaria remain incompletely elucidated and there have been few recent investigations of its pathobiology. Historic passive transfer experiments performed during the twentieth century provide support for a 'photoallergy' model of disease pathogenesis, wherein molecular alteration of a putative chromophore by solar electromagnetic radiation produces mast cell activation via an IgE-dependent mechanism. However, this model does not account for several observations made during passive transfer experiments nor does it explain a range of subsequent clinical and photobiological observations made in solar urticaria patients. Furthermore, increased understanding of the molecular dynamics underpinning cutaneous mast cell responses highlights the need to reformulate our understanding of solar urticaria pathogenesis in the context of this contemporary scientific landscape. In this review, we discuss the current understanding of solar urticaria pathogenesis and, by incorporating recent scientific and clinical observations, develop new hypotheses to drive future investigation into this intriguing disorder.

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

BACKGROUND

Solar urticaria (SU) is a rare photodermatosis causing a significant impact on patients' quality of life (QoL), and treatment is often challenging.

AIM

To analyse clinical experience with a tailored stepwise therapeutic approach.

METHODS

A retrospective cohort design was used. Patients with suspected SU underwent laboratory investigations and photoprovocation. Those with a high minimal urticaria dose (MUD) were treated with a single antihistamine (protocol 1), and those with a lower MUD received three types of antihistamines (protocol 2); both protocols included a leucotriene receptor antagonist (LRA). In cases of failure, treatment was switched to omalizumab at doses of < 300 mg/month with incremental dosage increases as necessary (monthly dose range, 150-600 mg/month). Symptom relief and photoprovocation under treatment were evaluated.

RESULTS

In total, 30 patients (10 men, 20 women) were enrolled. Most (87%) were sensitive to visible light (1-70 J/cm² ) with or without extension to ultraviolet A. Of the 30 patients, 23 opted for our stepwise approach: 22 achieved complete remission on protocols 1 or 2 (n = 17) or after switching to omalizumab (n = 5), and another patient achieved partial remission under omalizumab. There were no treatment-related severe adverse effects.

CONCLUSIONS

Symptoms of SU can be well controlled by treatment with antihistamines and an LRA tailored to the degree of photosensitivity, followed by omalizumab in refractory cases. This has important implications for patient QoL.

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.

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.

Solar urticaria: Epidemiology and clinical phenotypes in a Spanish series of 224 patients

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.

Solar urticaria

Solar urticaria is a rare IgE-mediated and chromophore-dependent photodermatosis. In some cases, these chromophores, designated as "serum factor", may be detected in serum or plasma. To date, the exact pathogenesis of solar urticaria has, however, not been elucidated. Typical clinical features include the onset of urticarial lesions within a few minutes after light exposure, which already raises diagnostic suspicion. The most common triggers are UVA and visible light. Determination of the action spectrum as well as the minimal urticarial dose (MDU) is diagnostically crucial. Other photodermatoses such as polymorphic light eruption or porphyrias (especially erythropoietic protoporphyria) have to be ruled out. Apart from sunlight avoidance, which is always required, further therapeutic options used include nonsedating antihistamines as well as light hardening. Newer treatment modalities such as plasmapheresis or the anti-IgE antibody omalizumab are reserved for severe, recalcitrant forms of solar urticaria.

Update on pediatric photosensitivity disorders

PURPOSE OF REVIEW

Although rare in the pediatric population, photosensitive dermatoses may begin prior to adulthood. The causes of photosensitivity are diverse, ranging from primary, immunologically mediated disorders of photosensitivity to inherited genetic or metabolic disorders. This review will highlight the key features of these disorders to familiarize the pediatric practitioner with their symptoms and any associated extracutaneous clinical or laboratory findings that may accompany them.

RECENT FINDINGS

New developments in the field of pediatric photosensitivity have been scant over recent years. While mechanisms of photosensitivity and genetic underpinnings associated with various conditions such as xeroderma pigmentosum continue to be uncovered, the literature on disorders of photosensitivity has been otherwise without many recent significant advances.

SUMMARY

Although the differential diagnosis of pediatric photosensitivity disorders is broad, it is often possible to establish the diagnosis by following an algorithmic approach. Once the correct diagnosis is rendered, this will guide any further workup that needs to be performed as well as specific management strategies.

Photodermatoses in pigmented skin

Photodermatoses are a group of skin diseases primarily caused by, or exacerbated by exposure to ultraviolet and or visible radiation. The effect of sunlight on skin depends on a number of factors including skin colour, skin phototype and the content and type of melanin in the skin. There are only a few studies describing photodermatoses in populations with dark skin. A PubMed search was conducted to summarize currently available information on differences in biology of melanin in dark and light skin and photodermatoses in dark skin. Dark skin is characterised by higher content of melanin, higher eumelanin to pheomelanin ratio, lower tyrosinase activity, and more effective distribution of melanin for protection against ultraviolet light. Photodermatoses are common in dark skinned patients with some variation in the spectrum of photodermatoses. Polymorphous light eruption (PMLE) is the commonest, followed by chronic actinic dermatitis. Pin-point papular and lichenoid variants of PMLE and actinic lichen planus are more frequent in dark skin whereas actinic prurigo, solar urticaria and hydroa vacciniforme are uncommon. Photodermatoses are common in dark skinned patients despite better natural photoprotection. It is proposed that lichenoid photodermatoses may be added to the classification of photodermatoses in dark skin.

Leukocytoclastic vasculitis in urticaria induced by sun exposure

BACKGROUND

Solar urticaria manifests itself immediately after solar or artificial light exposure and disappears a little later. Histopathologic findings of solar urticaria are essentially identical to those of classic urticaria.

CASE REPORT

We report a 41-year-old man who developed urticarial lesions some hours after sunlight exposure, which resolved after approximately 1 week. Histologic examination of the lesions evidenced a leukocytoclastic vasculitis.

CONCLUSION

In a literature review we found one case of solar urticaria with histologic aspects of leukocytoclastic vasculitis.

Analysis of photodermatoses seen in a predominantly Asian population at a photodermatology clinic in Singapore

BACKGROUND

The idiopathic photodermatoses have been reported to be rarer in tropical Singapore than in countries of higher latitude, with photoaggravated dermatoses and systemic phototoxicity making up most of the photodermatoses seen here. This study aims to reassess the spectrum of photodermatoses seen at the National Skin Centre, Singapore, compared with almost a decade ago, and analyse the clinical and photobiological characteristics, as compared with other countries.

MATERIALS AND METHODS

We reviewed the clinical data of 141 patients phototested from January 2000 to December 2001, and analysed the epidemiological, clinical and photobiological features.

RESULTS

Photosensitive dermatoses were diagnosed in 88% (124/141) of patients phototested. In those diagnosed with photodermatoses, polymorphic light eruption (PMLE) (28%) was the most common diagnosis, followed by photoaggravated dermatoses (26%), chronic actinic dermatitis (CAD) (15%), systemic phototoxicity (15%), solar urticaria (SU) (7%), actinic prurigo (AP) (5%) and photoallergic contact dermatitis (4%). Ethnic Indians appeared to be more predisposed to PMLE; AP was diagnosed only in ethnic Chinese. The other photodermatoses occurred proportionally in all racial groups. AP differed from that found in Caucasians, being of adult onset and persistent. Abnormal phototest results were obtained in all patients with CAD, SU and AP, but only in 56% and 49% of systemic phototoxicity and PMLE, respectively.

CONCLUSION

Idiopathic photodermatoses are more commonly diagnosed in Singapore than a decade ago, while the incidence of systemic phototoxicity has remained stable. The spectrum of photodermatoses in our Asian population now approximates that seen in Caucasian cohorts.

Urticaria solar. Estudio de 20 casos

INTRODUCTION

Solar urticaria is an infrequent disorder, but is probably underdiagnosed. It is characterized by the sudden appearance of weals in areas that are not usually photoexposed after exposure to the sun or to artificial sources of visible or ultraviolet light. Few cases have been published in literature, so the information available about this disorder and its natural evolution is limited.

MATERIAL AND METHODS

We have compiled data from 20 patients diagnosed with solar urticaria in our department in the last 12 years (1990-2002) in order to try to obtain information about the characteristics of this condition.

RESULTS

As the most relevant characteristics of our series, we can mention the fact that 60 % of the patients were women, and the average duration of the condition before consulting a dermatologist was 3 years. In 55 % of the patients, areas that are usually photoexposed, such as the face and hands, were less severely affected (due to acclimatization or hardening). The spectra responsible for the SU were visible light, UVA and UVB, in that order. With regard to treatment, we obtained a partial response with antihistamines and photoprotectors, and good results using progressive desensitization with UVA/sunlight.

CONCLUSION

Solar urticaria is probably an underdiagnosed condition in our milieu. There are few series in literature that provide any information about the most significant characteristics of this disorder. We have compiled the most relevant data from our patients and we have compared it with the other published series in an attempt to learn more about this photodermatosis.

Physical urticaria

Physical urticarias are a unique subgroup of chronic urticaria in which patients develop urticaria secondary to environmental stimuli. Common triggers include exercise, temperature changes, cold, heat, pressure, sunlight, vibration, and water. Systemic symptoms have occurred during severe episodes. Physical urticarias are responsible for approximately 20% to 30% of all cases of chronic urticaria. A basic knowledge of these unusual disorders is important for all healthcare providers. This article covers the following types of physical urticarias: dermatographism, cholinergic urticaria, local heat urticaria, exercise-induced anaphylaxis, vibratory angioedema, solar urticaria, and aquagenic urticaria.

Solar urticaria in Singapore: an uncommon photodermatosis seen in a tertiary dermatology center over a 10-year period

BACKGROUND

Solar urticaria is an uncommon photodermatosis, characterized by the appearance of pruritic wheals after sun exposure. In this study, we examine the photobiological characteristics of solar urticaria in the heterogeneous group of Singaporean patients.

METHODS

The photobiological features of all patients treated for solar urticaria at a tertiary dermatology center in Singapore over a 10-year period were retrospectively examined.

RESULTS

A total of 19 patients were diagnosed to have solar urticaria from 1993 to 2002. The mean age at diagnosis was 26 years, with a racial distribution of 17 (90%) Chinese, one (5%) Malay, and one (5%) Indian. Fifteen (79%) patients were males and four (21%) were females. The face/neck (47%) and arms/forearms (58%) were most often affected. Six (32%) patients had a history of atopy and two (11%) had dermographism. Fifteen (79%) patients had Fitzpatrick's skin type IV, three (16%) had skin type III and one (5%) patient had skin type V. The mean exposure time to wheal formation was 23 min. The action spectra of solar urticaria were visible light for 12 (63%) patients, ultraviolet (UV) A for one (5%), visible light and UVA for five (27%), and natural sunlight for one (5%) patient. All patients reported partial improvement with a combination of antihistamines and sunscreens as the main modality of treatment.

CONCLUSIONS

Our data suggest that solar urticaria is an uncommon photodermatosis and a rare form of urticaria. Wheals were mostly elicited by visible light and/or UVA. A combination of antihistamines and sunscreens provided a useful form of therapy for patients with solar urticaria.

Diagnosis and treatment of solar urticaria

Solar urticaria is one of the most annoying of the photodermatoses. It can be difficult to diagnosis because of phototesting problems, and it is not easy to treat. The different treatment modalities available all have their practical problems, so it is difficult to provide the patient with adequate protection. In many patients, however, treatment can reduce the symptoms and allow regular exposure of the skin to natural sunlight as the skin becomes more tolerant to the provoking wavelengths, the result being more complete protection.

Analysis of patients with suspected photosensitivity referred for investigation to an Australian photodermatology clinic

BACKGROUND

Australia's first dedicated photodermatology clinic was established at St Vincent's Hospital Melbourne in 1993.

OBJECTIVE

We sought to review clinical diagnoses and results of investigations performed on patients seen at this institution.

METHODS

A database was created to enable a retrospective and prospective analysis of all patients attending for evaluation of suspected photosensitivity from April 1993 to October 2000.

RESULTS

A total of 513 patients were seen, 289 (56.3%) female and 224 (43.7%) male, with a mean age of 45.2 years (range: 2.6-85.9). A photosensitive disorder was diagnosed in 397 patients (77.4%), with the acquired idiopathic photodermatoses accounting for diagnoses in 215 (41.9%) of all patients seen. The most common diagnosis was polymorphous light eruption. Reduced minimal erythema doses were seen in 25.3% of all patients light tested. In those photopatch tested, 23.3% had at least 1 photocontact reaction. Allergic contact dermatitis in a photosensitive distribution was diagnosed in 7.4% of the clinic population.

CONCLUSION

A large proportion of referrals to a photodermatology clinic comprise people with acquired idiopathic photodermatoses, with other common diagnoses that may mimic photosensitivity including allergic contact dermatitis, atopic dermatitis, and rosacea.

[Etiological diagnosis and treatment of chronic urticaria]

PURPOSE

Urticaria is a muco-cutaneous illness which is characterized by a dermal or hypodermal oedema due to a vasodilatation attributed to the release of histamine by mast cells and basophils. Urticaria is a very common complaint, since among 20% of the population will experience at least one episode of urticaria during their life. Chronic urticaria by definition is daily and has persisted for at least six weeks. By contrast with acute urticaria, its etiological and therapeutic approaches can present a significant challenge, leadind to repeated examinations.

CURRENT KNOWLEDGE AND KEY POINTS

Questioning and clinical examination are essential for the etiological diagnosis of chronic urticaria, because they are able to lead rapidly to the suspicion of several causes which can be eradicated to treat the symptoms. If no cause is found, further investigations may be required. Recent studies have shown the lack of profitability of exhaustive laboratory investigations. Thus, many authors at present time advise minimal and non expensive investigations which are determinated by anamnestic data. But most often, the etiology of urticaria remains unknown and this situation leads to the diagnosis of chronic idiopathic urticaria. The treatment of chronic urticaria is above all based on the elimination of the symptoms, either on a specific fashion if the etiological diagnosis is already known, or in a non specific way. The anti-H1 agents are the medications of choice for first line treatment.

FUTURE PROSPECTS AND PROJECTS

Pathophysiology of chronic urticaria is to date well established. As the mechanisms responsible for chronic urticaria are better defined, more therapeutic agents, which are effective on other targets than histamine, should become available. Moreover, recent advances have supported the notion that an underlying autoimmune process could account for many cases of chronic "idiopathic" urticaria. In such severe and refractory urticaria, immunomodulation therapy may bring about clinical improvement.

Changes of photosensitivity and action spectrum with time in solar urticaria

BACKGROUND

Solar urticaria is a rare photosensitivity disorder characterized by the rapid onset of a pruritic, erythematous and urticarial rash following sun-exposure. The action spectrum and degree of photosensitivity have been observed to change over time in several isolated reports.

METHODS

Monochromator phototesting was performed on multiple occasions on 12 patients with solar urticaria.

RESULTS

Six patients demonstrated normal responses in the initial phototest. They remained normal in five patients upon subsequent testing. Seven patients demonstrated abnormal immediate responses, most frequently at UVA wavelengths. Within some individuals, variations in action spectrum and/or degree of photosensitivity were observed over the years, but not over days.

CONCLUSION

Significant changes in action spectrum and degree of photosensitivity may occur over years in solar urticaria. However, changes over shorter periods of time are likely to be minor and not have clinical significance.

Idiopathic photodermatoses: clinical, diagnostic and therapeutic aspects

Idiopathic photodermatoses are a group of photosensitivity dermatoses, which are not very frequent with the exception of polymorphous light eruption. Therefore, their recognition may not be easy for dermatologists who are not familiar with photosensitivity diseases.

LEARNING OBJECTIVE

The information in this review is intended for giving clinical, diagnostic and therapeutic clues for the correct management of patients. Clinical features will be described together with diagnostic relevant procedures and usual therapeutic measures.

Pathomechanisms in physical urticaria

Various exogenous stimuli, e.g., rubbing, pressure, cold, heat, or electromagnetic waves, have been described to elicit whealing reactions, the so-called physical urticarias. They may occur as isolated diseases or in association with other types of urticaria. In many cases, the respective physical factors can be defined exactly, e.g., the degree of temperature changes or the range of eliciting ultraviolet wavelengths. In contrast, the underlying pathomechanisms are mostly still obscure. In the past, often contradictory results have been reported regarding the role of IgE, complement factors, histamine, or even mast cells. Recently, many investigations have been performed on solar urticaria where subgroups of patients with different clinical and pathophysiologic features could be defined and mechanisms of tolerance induction have been studied that also offered an efficient treatment modality. Therefore this review will mainly focus on this type of disease as a paradigm of the pathomechanisms of physical urticaria.

The clinical and photobiological characteristics of solar urticaria in 40 patients

Forty patients with solar urticaria, 16 male and 24 female, were examined personally during the past 25 years. The median age at onset of symptoms was 32 years, ranging from 13 to 76 years. Most commonly (45%) solar urticaria first appeared during the third decade. The mean duration of the disease was 3.6 years at presentation. The action spectrum was found in the visible light range in 24 patients (60%), in the ultraviolet (UV) A range in four, in the UVB in four, from the UVA to UVB in three, from the UVA to visible light in one and in a broad range from UVB to visible light in four patients. An inhibition spectrum was detected in 13 of 19 patients (68%), occurring at longer wavelengths than the action spectrum in 12 of these cases. The augmentation spectrum was found in only four of 14 patients (29%) examined. Twenty-four of 31 patients (77%) developed an urticarial reaction to autologous serum, which had been previously irradiated in vitro at the action spectrum for that patient. In a single patient, solar urticaria was caused by a drug, namely chlorpromazine. In two patients, polymorphic light eruption occurred in association with solar urticaria. No single modality of treatment was satisfactory, but combined use of antihistamines, sunbathing, psoralen UVA photochemotherapy and/or sunscreening agents partially suppressed the symptoms.