Diagnosis and treatment of actinic prurigo

Actinic prurigo (AP) is an idiopathic photodermatosis that affects mainly the mestizo population in Latin America. It has an early onset, a slight predominance in women, and affects the sun-exposed areas of the skin, causing erythematous papules and lichenified plaques secondary to intense and chronic pruritus. Lesions can be induced by both ultraviolet A (UVA) and ultraviolet B (UVB). An association with several human leukocyte antigen (HLA) alleles has been reported. AP is unique among all photodermatoses in its remarkable response to thalidomide. In the past the microscopic features of AP have been considered as nonspecific; however, the constant finding of dense lymphocytic inflammatory infiltrates and the immunogenetic features of AP support the existence of an immunologic mechanism in its pathogenesis.     

What is actinic prurigo in Britain?

Actinic prurigo (AP) belongs to the group of idiopathic photodermatoses sharing a predilection for occurring more commonly in females, and there is much controversy as to whether it is only a more severe form of polymorphous light eruption (PMLE) or whether it is a distinct entity in its own right. The condition is characterised by intensely itchy papules, plaques and nodules, along with excoriations and scars usually starting before puberty, and predominantly involves the sun-exposed areas although it may also affect covered sites. Seasonal exacerbations at the beginning of spring with improvement in the fall are typical, although the lesions frequently do not clear completely in the winter. The disorder may run a chronic course and persist into adulthood, but often spontaneous resolution occurs in late adolescence. Diagnosis is predominantly based on the clinical features, cutaneous irradiation tests and histology often being normal or non-specific. HLA typing has also been performed in both PMLE and AP patients, showing a strong association between HLA-DR4, in particular with the DRB1*0407 subtype, and AP; no HLA association has been found in PMLE. This HLA association is likely to be of pathogenic significance and strongly suggests a critical role for MHC-restricted antigen presentation in the development of photosensitivity AP.     

A case of actinic prurigo in Thailand

Actinic prurigo is a separate entity from the polymorphous light eruption that affects American Indians. It has been reported mainly from North and South America, with only few reported cases from Britain or Asia. We report a case of actinic prurigo in a Thai girl who showed cheilitis and pruritic papules on exposed areas for three years. We were able to induce populovesicular lesions by three consecutive irradiations with 100 J/cm2 UVA and 2 minimal erythematous dose of UVB. However, three weeks after irradiation, a prurigo papule developed at the UVB irradiated site.     

Adult-onset actinic prurigo in Thailand

BACKGROUND: Actinic prurigo (AP) is one of the rare idiopathic photodermatosis. It is said to be a familial disease and is usually seen in certain specific geographical areas. The adult-onset type of AP is reported less frequently in the Asian population and has never been reported in Thailand. METHODS: The study population comprised 30 patients. Demographic data were collected. Photo-tests and photo provocation tests for UVA, UVB and visible light were carried out on non-exposed skin. The other investigations included antinuclear antibody, anti-HIV antibody and urine porphyrin level. Histopathology studies were also carried out. RESULTS: There were 18 males and 12 females. The mean age of onset was 36.86 years. The duration of disease was from 1 month to 20 years. Forearms (27 patients) were the most frequently affected site. Other screening tests showed negative results. Five patients had abnormal MED to UVA and one patient had abnormal MED to UVA as well as UVB. Photo provocation tests showed positive responses to both UVA and UVB in 12 cases (40%), a positive response to UVA in 11 cases (37%), a positive response to UVB alone in four cases (13.3%) and a normal response in three patients (10%). None of the patients had a positive response to visible light. Skin biopsies were performed on nodular lesions in 23 cases. Histopathology from these 23 cases showed hyperkeratosis ortho- or parakeratosis and acanthosis in 20 of the 23 cases. CONCLUSIONS: Adult-onset AP in our country may have different geographic and racial distribution from previous reports or may be the tropical variant as described by Tham et al. It may not be an uncommon disease in our country, if there is increased awareness of this disease. Only 16.6% of patients had reduced MED. Photo provocation tests were positive in 90% of cases. Most of the positive wavelengths were UVA or both UVA and UVB. Therefore, photo provocation tests should be performed in cases suspected of AP. The prognosis for AP is not good, despite combinations of treatment. The disorder may run a chronic course. This may be because of our sunny climate and the sun-exposed occupations of patients.     

Clearance of pediatric actinic prurigo with dupilumab

Actinic prurigo is a rare, idiopathic chronic photodermatosis of childhood characterized by excoriated papules, nodules, and plaques in sun-exposed areas. It is notoriously difficult to treat. The disorder involves a type IV hypersensitivity reaction driven by both Th1 and Th2 inflammatory pathways, the latter of which leads to secretion of IL-4, IL-5, IL-13, and production of B cells, IgE, and IgG4. Dupilumab, an IL-4 receptor antagonist, disrupts the Th2 pathway. We present a pediatric patient with severe, recalcitrant actinic prurigo who achieved rapid and sustained clearance with dupilumab.     

Thalidomide: An option for the pediatric patient with actinic prurigo

Actinic prurigo (AP) is an immune-mediated photodermatosis that usually starts in childhood and is predominant among American indigenous and mestizo communities. In adults with AP, thalidomide is the treatment of choice; however, there is little information on its use in pediatric patients. We report the case of a 10-year-old girl with AP treated successfully with thalidomide.     

Patch testing in actinic prurigo

42 out of 93 Saskatchewan Indians (32 female (F) and 10 male (M] with actinic prurigo were patch tested to standard series allergens between 1983 and 1987. Positive reactions were most frequently seen with nickel (3F:2M) and colophony. All 3 positive patch tests to colophony were in males. The same patients were also patch tested to extracts of 21 Saskatchewan plants and 3 Hollister-Stier plant extracts. Only 1 male and 2 females had positive patch tests. None of these 3 had rashes on the eyelids, behind the ears or under the chin. We conclude that plant contact dermatitis is unlikely to be mistaken for actinic prurigo in Saskatchewan.     

Primary cutaneous B-cell lymphoma associated with actinic prurigo

We describe two patients with a diagnosis of actinic prurigo who subsequently developed cutaneous B-cell lymphoma. This is the first report, to our knowledge, of this association. We propose that chronic antigenic stimulation by ultraviolet radiation, in the context of actinic prurigo, may have been causal in the development of these unusual lymphomas.     

Disseminated superficial actinic porokeratosis with both typical and prurigo nodularis-like lesions

We report a 50-year-old Korean patient who developed a disseminated superficial actinic porokeratosis (DSAP) with two types of lesions. One was a typical DSAP lesion clinically and histopathologically. The other was clinically similar to prurigo nodularis, but histologic examination showed the findings of porokeratosis such as cornoid lamellae and loss of the granular layer in addition to those of chronic lichenified dermatitis, so it could be described as prurigo nodularis-like porokeratosis. The nodular lesions seemed to develop on preexisting typical lesions of DSAP mainly during the summer by the aggravation of pruritic symptoms and scratching associated with sun exposure. Although we could not find any published reports describing lesions like those of our case, we think that such prurigo nodularis-like porokeratosis can develop in patients with DSAP in some situations involving pruritus and scratching.     

Association of HLA subtype DRB10407 in Colombian patients with actinic prurigo

BACKGROUND: Human leukocyte antigen (HLA) DRB1*0407 had been associated with actinic prurigo in different populations. This class II HLA-DR subtype had not been studied in Colombia. OBJECTIVE: The objective of this study was to establish whether there was an association of actinic prurigo with HLA DR in a Colombian population. MATERIALS AND METHODS: Forty patients with a clinical diagnosis of actinic prurigo and 40 healthy subjects, paired by age, sex and birthplace, were studied. HLA typing for HLA DRB1 and DRB1*04, if necessary, was performed by the PCR-SSP method using blood samples. RESULTS: A high frequency of HLA DRB1*0407 was found in the patients (97.5% vs. 30%; P<0.00001). The allelic frequency of HLA DRB1*0407 was 63.8% in the case group, and 14.5% in the controls (P<0.00001). In the control group, there was a higher frequency of the alleles DRB1*01 (14.5% vs. 1.25%; P=0.0027) and DRB1*13 (23.7% vs. 2.5%; P=0.00013). LIMITATIONS: The small number of controls does not allow us to drive conclusions about other HLA alleles. CONCLUSIONS: HLA subtype DRB1*0407, found in actinic prurigo patients in studies conducted in England, Scotland, Ireland and Mexico, was also associated in Colombian patients. This finding, concordant in patients from different ethnic groups, could be helpful in the diagnosis of this disease and probably important in its pathogenesis. DRB1*01 and DRB1*13 alleles were more frequent in controls than in patients; we do not know whether they play any role in the resistance to the disease.     

Chronic prurigo: A retrospective study of 168 cases

Chronic prurigo is classified into two clinical subtypes: prurigo nodularis (PN) and prurigo chronica multiformis (PCM) in Japan. In this study, we retrospectively investigated the clinical features of 168 patients with chronic prurigo (103 with PN and 65 with PCM) diagnosed at the Tokyo Medical and Dental University, and compared age, sex, prevalence of comorbidities, blood test results, histology and treatment efficacy in both groups. We found that patients with PCM were significantly older than those with PN. Males were more frequently diagnosed with PCM than females; however, both sexes were similarly affected by PN. Chronic infection was more prevalent in PN, whereas diabetes was more common in PCM. For both subtypes, serum immunoglobulin E levels were elevated above the normal range. However, serum thymus and activation-regulated chemokine/CCL17 levels and the number of blood eosinophils were significantly higher in patients with PCM than in those with PN. Histologically, much higher numbers of CD4⁺ cells than CD8⁺ cells were distributed in the lesions of both subtypes. Eosinophils were distributed predominantly in intracollagenous lesions in PCM but were observed mainly in perivascular lesions in PN. There were no differences in basophil and mast cell distributions in the lesions of the two groups. Treatment efficacy was also similar in both subtypes. Together, both subtypes exhibit inflammation patterns predominantly driven by T-helper 2 cells. With respect to PCM, elevated numbers of blood eosinophils and the recruitment of these cells into intracollagenous areas may be important for pathogenesis.     

A case of actinic prurigo showing hypersensitivity of skin fibroblasts to ultraviolet A (UVA)

We here report a patient with actinic prurigo. He had had erythematous papulovesicular eruptions on the sun-exposed sites from fall to early summer for 4 years. The lesions healed leaving atrophic scars. The histology showed epidermal necrosis and dermal dense perivascular lymphohistiocytic infiltration and edema. His minimal erythema doses to ultraviolet B (UVB) and UVA were normal and lowered, respectively. Skin lesions were produced by repeated irradiation with UVA plus UVB, but not with UVA alone. Then he was diagnosed as having actinic prurigo. Skin fibroblasts from the patient were hypersensitive to UVA. We believe that the hypersensitivity relates to the pathomechanisms of the photosensitivity in the case. UVA sensitivity of fibroblasts may be useful for differentiating actinic prurigo, hydroa vacciniforme, and other similar photosensitive disorders.     

Guidelines for the management of actinic keratoses

These guidelines stemmed from a consensus meeting held by the British Photobiology Group (BPG) in 1999. Following this meeting one of the authors (J.M.M.) was invited to draw up guidelines for the management of actinic keratoses by the British Association of Dermatologists Therapy Guidelines and Audit Subcommittee. Relevant evidence was sought using the search terms 'solar keratosis' and 'actinic keratosis' in Medline from 1966 onwards. Additional and earlier literature was reviewed on the basis of references within post-1966 publications. All articles of apparent relevance were reviewed independently of the nature of the publication. The quality of the evidence elicited has been indicated. The National Ambulatory Medical Care Survey (U.S.A.) was used for further data on topical chemotherapy. Papers were reviewed and discussed by the contributors to the BPG Workshop (see Acknowledgments). Recommendations are evidence based where possible. Strength of recommendation is coupled with quality of evidence. Strength of recommendation includes consideration of apparent cost-benefit and practical considerations. Quality of evidence reflects the nature of the trial structure that provides data of efficacy.     

A candidate gene analysis of three related photosensitivity disorders: cutaneous lupus erythematosus, polymorphic light eruption and actinic prurigo

BACKGROUND: Polymorphic light eruption (PLE) is a common inherited photosensitivity disorder, which may predispose to several related but distinct conditions, including subacute cutaneous lupus erythematosus (SCLE), discoid lupus erythematosus (DLE) and actinic prurigo (AP). OBJECTIVES: To examine specific candidate genes for shared susceptibility alleles between these related phenotypes. METHODS: Eighty-five caucasian patients with annular SCLE or DLE were recruited, in addition to 102 first-degree relatives. The prevalence of PLE in both the patient and relative groups was determined by detailed interview and clinical examination. Eighty-five patients with pure PLE and 59 patients with AP were also recruited. Candidate genes were analysed by typing of single nucleotide polymorphisms of IL10 (-1082 G/A and -819 C/T), FCGR2A (131 R/H), SELE (128 S/R), ICAM1 (241 G/R and 469 E/K), IL1A (+ 4845 G/T), IL1B (-511 C/T and + 3954 C/T), IL1RN (+ 2018 T/C) and TNF (-308 G/A) using polymerase chain reaction (PCR) with sequence-specific primers and 5'-nuclease PCR. RESULTS: A significant association was found between SCLE and the rare TNF -308 A allele when compared with patients with DLE (P = 0.043), PLE (P = 0.001), AP (P < 0.001) and healthy controls (P < 0.001). However, there was strong linkage disequilibrium between TNF -308 A and the HLA A*01, B*08, DRB1*0301 haplotype. A negative association was also found between SCLE and the IL1B + 3954 T allele (P = 0.039), but the significance was lost on correction for multiple testing. CONCLUSIONS: We have demonstrated the association of SCLE with the rare TNF -308 A allele, which may be pathogenic or, alternatively, a marker allele for the extended HLA A*01, B*08, DRB1*0301 haplotype that is associated with a number of autoimmune conditions. Although many of the other loci that we chose failed to demonstrate an association, a candidate gene approach remains the most logical one, and the most likely to yield positive results in the future.     

Successful thalidomide therapy for actinic prurigo in a European woman

Actinic prurigo is a rare, often difficult‐to‐treat, idiopathic photodermatosis. Actinic prurigo is divided into a hereditary form appearing in the Native American population and a sporadic form occurring in non‐Native Americans. We present a 28‐year‐old Caucasian woman who developed typical clinical signs and symptoms of actinic prurigo, just as had her mother and grandmother. The patient and her mother were HLA‐A24 and HLA‐DR 4 with the subtype HLA‐DRB1*0408. Based on clinical symptoms and the HLA pattern, the diagnosis of actinic prurigo was made. Treatment with thalidomide led to resolution of the disease. This case report of a Caucasian woman suffering from a hereditary form of actinic prurigo questions the established classification of actinic prurigo into a hereditary Native American form and a sporadic form occurring in the non‐Native American population.     

Dermoscopic features of actinic keratosis

Actinic keratosis (AK) is a keratinocytic neoplasm that typically develops on sun‐damaged skin of elderly individuals. Only a few reports so far have described the dermoscopic diagnostic features of AK, mainly focusing on facial non‐pigmented AKs. A typical feature of facial non‐pigmented AK is a composite pattern named “strawberry pattern”, characterized by a background erythema/red pseudonetwork consisting of unfocused, large vessels located between the hair follicles, associated with prominent follicular openings surrounded by a white halo. Dermoscopic characteristics of pigmented AK on the face include multiple slate‐gray to dark‐brown dots and globules around the follicular ostia, annular‐granular pattern and brown to gray pseudonetwork. Recognizing specific dermoscopic features of AK can be useful in guiding the clinician in the differential diagnosis of AK with melanocytic skin lesions such as LM and non‐melanocytic lesions. Histopathologic examination should be performed whenever clinical and/or dermoscopic differential diagnosis is inconclusive.     

Coexistence of adult-onset actinic prurigo and shampoo dermatitis: A case report

Actinic prurigo is a rare and acquired idiopathic photodermatosis. It usually shows childhood onset and female predominance. Here, we present an unusual case of a male patient with coexistence of adult-onset actinic prurigo and shampoo-induced allergic contact dermatitis. He was initially diagnosed with actinic prurigo. However, after detailed examination of the distribution of the rash, careful collection of his history, and interpretation of the results of histopathologic analysis, photo test, patch test, and photopatch test, coexistence of adult-onset actinic prurigo and shampoo-induced allergic contact dermatitis associated with cocamidopropyl betaine was diagnosed. The rash improved after appropriate use of sunscreen and avoidance of shampoo containing this allergen. Dermatologists should be aware of the possibility of concurrent photodermatitis and contact dermatitis.