The Global Hidradenitis Suppurativa Atlas Methodology: Combining Global Proportions in a Pooled Analysis.

INTRODUCTION: Data concerning the global burden of hidradenitis suppurativa (HS) are limited. Reported prevalence estimates vary between 0.0003% and 4.1%, and data from various geographical regions are still to be collected. Previously reported prevalences have been limited by the methodological approach and source of data. This has resulted in great heterogeneity as prevalence data from physician-diagnosed cases poorly match those of self-reported apparent HS disease. METHODS: The Global Hidradenitis Suppurativa Atlas (GHiSA) introduces an innovative approach to determine the global prevalence of HS. This approach involves using a previously validated questionnaire to screen apparently healthy adults accompanying a patient to a non-dermatological outpatient clinic visit in a hospital or a private/family medicine clinic. The screening questionnaire (i.e., the index test) is combined with a subsequent physician-based in-person validation (i.e., the reference standard) of the participants who screen positive. Approximately ten percent of the screen-negative participants are also clinically assessed to verify the diagnostic precision of the test. The local prevalence (pi) will be estimated from each country that submits the number of patients who are HS positive according to the index test and clinical examination (n), and the corresponding total number of observations (N). CONCLUSION: The GHiSA Global Prevalence studies are currently running simultaneously in 58 countries across six continents (Africa, Europe, Australia, North America, South America, and Asia). The goal of the combined global proportion is the generation of a single summary (i.e., proportional meta-analysis), which will be done after a logit transformation and synthesized using a random-effects model. The novel standardization of the Global Prevalence Studies conducted through GHiSA enables direct international comparisons, which were previously not possible due to substantial heterogeneity in past HS prevalence studies.

Prevalence of Hidradenitis Suppurativa in an African Population: Validation of a Screening Questionnaire in Lagos, Nigeria.

BACKGROUND: Epidemiologic hidradenitis suppurativa (HS) studies from Africa are lacking. This study aimed at uncovering the prevalence of HS in Lagos, Nigeria, to validate an HS screening questionnaire, and to contribute to the Global Hidradenitis Suppurativa Atlas (GHiSA). METHODS: This was a cross-sectional study of 802 healthy adults accompanying their relations to the outpatient clinic of Family Medicine and Ophthalmology at the Lagos State University Teaching Hospital in Lagos, Nigeria, following ethical approval. Verbal and written consents were obtained prior to inclusion of study participants. The study was conducted using a validated screening questionnaire. Screen-positive and randomly selected screen-negative participants were clinically examined. Severity was categorized using the Hurley score. RESULTS: The prevalence of HS in the sample was 2.2% (18/802; 95% CI: 1.4-3.5%) with no gender predominance. The mean age in the HS group was 34 years (IQR 28-42) and the median body mass index (BMI) of the HS patients was 27.0 (IQR 21.4-28.6). There was no significant difference in BMI between the HS and control group. The screening questionnaire had a sensitivity of 1 (18/18), specificity of 0.8 (20/25), positive predictive value of 0.8 (18/23), and a negative predictive value of 1 (20/20). The axilla was the predominant site of affection (66.7%), and all HS patients were classified as mild disease (Hurley score 1). CONCLUSION: The prevalence of HS in Lagos, Nigeria, was 2.2% and, in this population, BMI did not appear to be a risk factor. The axilla was the most affected site, and all patients had a mild disease severity (Hurley score 1). Finally, the HS screening questionnaire is a suitable tool in population surveys.

Long-Term Follow-Up after Radiotherapy of Hidradenitis Suppurativa.

BACKGROUND: Patients with hidradenitis suppurativa (HS) are still often disappointed with the current treatments offered and there is a clear demand for more effective options. Since the late 1990s there has been a revival in the use of radiotherapy (RT) for different benign diseases, including HS. During the past 20 years one case series and some scattered case reports have described promising results of RT. OBJECTIVES: To evaluate the long-term efficacy of RT in early-stage HS. METHODS: A postal survey-based long-term follow-up with simple factual questions of partly retrospective and partly contemporary characteristics was performed. Sixty-four patients (96 axillae), diagnosed with mild to moderate HS were irradiated with a orthovoltage unit with 100 kV, 3 mm Al or 200 kV, 0.5 Cu filtering, respectively. Four to six biweekly fractional doses ranging from 0.75 to 1 Gy up to a total dose of 6 Gy in one series, and in chronic cases followed by four daily fractions of 2 Gy up to a total dose of 14 Gy, were given. Late treatment toxicity and the rate of remission of the disease were evaluated. RESULTS: The overall response rate of the survey was 64.1% with 40.6% (26/64) valid, complete questionnaires. In total, 40 axillae were irradiated in these 26 patients. After a median follow-up of 40 years (range 32-52) complete remission of the lesions occurred in 34 of the 40 sites (85%). None of the 26 patients with 40 irradiated sites reported adverse effects at the time of the survey. CONCLUSIONS: RT appears to be an effective treatment for early and mild HS in the majority of patients. In this case series, no side effects were reported after a median follow-up period of 40 years.

Mammary Hidradenitis Suppurativa Lesions - A Suggestion for Phenotyping.

BACKGROUND: Hidradenitis suppurativa (HS) is an under-diagnosed chronic inflammatory skin disease of the pilosebaceous unit of apocrine gland-rich parts of the body. The mammary area is the fourth most HS-affected area and, as typical lesions include non-fluctuating nodules, abscesses, and tunnels/sinus tracts, mammary HS is often mistaken for other mammary "boils", such as sub-areolar and granulomatous non-lactating breast abscesses. Our objective was to present a spectrum of mammary HS lesions, explore a possible classification, and expose mammary HS as a possible differential diagnosis to non-lactational breast abscesses. METHODS: A cross-sectional study on current and newly-referred patients treated for HS affecting the mammary area. Anamnestic information, subjective outcome measures, and lesion counts including anatomical location were collected. Patients with similar morphologies were grouped, and characteristics for the groups were investigated. LIMITATIONS: We were not aware of the number of morphologies we would find, and as a result the study did not have sufficient power to show significant differences after correction for multiple testing. RESULTS: We found three morphologically different subtypes of mammary HS; the Sternal, the Frictional, and the Nodule types. These groups differed in anatomical lesion characteristics and other patient characteristics. Furthermore, we found a fourth Mixed type - a combination of the other three. CONCLUSION: Differential diagnosis between mammary HS and sub-areolar or granulomatous non-fluctuating non-lactating breast abscess is most easily performed by assessing the precise anatomical location of the lesion and determining if the mammary lesion is the only lesion present or if similar lesions exist in other HS-specific areas.

Mechanical forces and Hidradenitis Suppurativa.

The mechanism by which inflammatory skin disease forms localized patterns of lesions is poorly understood. Hidradenitis suppurtiva (HS) is strikingly located to intertriginous areas. These areas are subject to considerable mechanical stress (friction, pressure and shear forces). Koebner phenomenon (KP) describes the appearance of typical skin lesions of a pre-existing dermatosis on previously clear skin following trauma, such as friction, pressure and more often penetrating injury with subsequent scarring. Striae distensae (SD) are a form of dermal scarring and can be considered as a form of inflammation-driven dermal disarray. Ectopic HS lesions may occur as KP due to trauma and locally increased susceptibility consisting of either altered mechanical qualities or inflammation. SD and mechanical stress may thus provide a model for the development of lesions. In the absence of an (animal) model or experiment, two patients are described who show HS (-like) lesions along co-localized with SD. The suggested two-hits model may be necessary for the development of KP in HS, that is that the general susceptibility, conferred by obesity, requires a local susceptibility factor to result in ectopic lesions. Ultimately, if ectopic HS lesions are considered true HS lesions it may be speculated that similar interaction occurs in the naturally stressed skin areas offering a possible explanation of the localized pattern of the disease.

Should Hidradenitis Suppurativa Be Included in Dermatoses Showing Koebnerization? Is It Friction or Fiction?

BACKGROUND: The etiology of hidradenitis suppurativa (HS) involves genetic and environmental factors. Well-established associated systemic factors are obesity, smoking, inflammation, and bacteria. Whether localized environmental factors such as friction and pressure may also play a causative role is still unclear. OBJECTIVE: To describe the possible Koebner phenomenon (KP) in HS. METHODS: The case notes on 14 patients with typical HS and additional HS lesions in previously uninvolved skin areas exposed to mechanical stress, e.g., on the abdomen at the level of the waistband, were reviewed with regard to the clinical characteristics of the cohort. RESULTS: All 14 patients (7 females) were obese with a mean BMI of 35.8 (range 30.1-45.0). All patients developed additional ectopic HS lesions at the sites of friction on the convex abdomen. The ectopic lesions were clinically and histopathologically similar to HS. CONCLUSION: Mechanical stress factors or trauma play a role in obese patients with HS. It is suggested that these new induced lesions fit the concept of the KP. This phenomenon seems to occur in the so-called frictional furunculoid type of HS and may explain the unique distribution at certain localizations on the body of this follicular cutaneous eruption. Removal in an early stage of HS of external stress factors that can lead to the KP should be part of the treatment, especially in obese patients.

Hidradenitis suppurativa is not associated with the metabolic syndrome based on body type: A cross-sectional study.

A body type with a high waist circumference or elevated waist-to-hip ratio (WHR), known as the "apple" body type, represents central/visceral obesity and is associated with the metabolic syndrome. The aim of this study was to simultaneously investigate the body mass index (BMI) and WHR in order to classify body types in individuals with hidradenitis suppurativa (HS) compared with a general dermatological population. A hospital-based cross-sectional study was performed in the Netherlands. One hundred and six HS patients and 212 controls were included. The BMI was significantly higher in the HS group in comparison with the control group, at 27.8 ± 5.4 and 25.6 ± 4.8, respectively (P < 0.001). The WHR did not significantly differ between HS patients and the control dermatological population (P > 0.05). A more peripheral pattern of bodyweight distribution was seen in 43% of the 37 obese HS individuals, in contrast to 19% of 31 obese patients in the control group (P = 0.036). In conclusion, the body type in obese HS patients, based on the WHR, shows a more peripheral pattern and differs from the WHR in the BMI-matched general dermatological population.

Inflammatory bowel disease is associated with hidradenitis suppurativa: Results from a multicenter cross-sectional study.

BACKGROUND: Hidradenitis suppurativa (HS) is often associated with inflammatory bowel disease (IBD; Crohn's disease or ulcerative colitis). However, the prevalence of IBD in HS patients is unknown. OBJECTIVE: To determine the prevalence of IBD in HS patients, and determine if patients with HS and IBD have a distinct HS phenotype. METHODS: For this multicenter, cross-sectional study, HS patients were asked during their first consultation if they had IBD. The diagnosis of IBD was checked in the medical files, and clinical characteristics were collected. RESULTS: IBD had a prevalence of 3.3% (95% CI 2.3-4.4) in 1076 HS patients. The prevalence of Crohn's disease was 2.5% (95% CI 1.6-3.4) and the prevalence of ulcerative colitis was 0.8% (95% CI 0.3-1.4). HS-IBD patients were less frequently obese (13.9% vs 31.2%, P = .04) than HS-only patients, but there were no differences in gender, family history of HS, disease severity, body areas affected by HS, or smoking status. LIMITATIONS: The prevalence might be underestimated since HS patients might still develop IBD. CONCLUSION: The prevalence of IBD in HS patients (3.3%) is 4-8 times higher than the prevalence in the general northern European population (0.41%-0.74%), however HS-IBD patients do not have a distinct HS phenotype.

Intralesional triamcinolone for flares of hidradenitis suppurativa (HS): A case series.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic inflammatory disease of the hair follicle. Standard practice of managing acute flares with corticosteroid injection lacks scientific evidence. OBJECTIVE: We sought to assess the outcomes of routine treatment using intralesional triamcinolone (triamcinolone acetonide 10 mg/mL) in the management of acute flares in HS. METHODS: This was a prospective case series evaluating the effect of intralesional corticosteroids for alleviation of acute flares in HS. Physician- and patient-reported outcomes were noted. RESULTS: Significant reductions in physician-assessed erythema (median score from 2-1, P < .0001), edema (median score from 2-1, P < .0001), suppuration (median score from 2-1, P < .0001), and size (median score from 3-1, P < .0001) was demonstrated at follow-up. A significant difference in patient-reported pain visual analog scale scores occurred after 1 day (from 5.5-2.3, P < .005) and from day 1 to day 2 (from 2.3-1.4, P < .002). LIMITATIONS: Small study size, open single-arm design, and short follow-up time are the limitations of this study. CONCLUSION: Intralesional injection of corticosteroids is perceived as beneficial by physicians and patients in the management of HS flares by reducing pain after 1 day and signs of inflammation approximately 7 days later.

Hidradenitis suppurativa (HS) is associated with low socioeconomic status (SES): A cross-sectional reference study.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic debilitating disease, whereby school attendance and employment can be disturbed. OBJECTIVE: We sought to determine the socioeconomic status (SES) in patients with HS relative to other dermatologic patients, and whether specific clinical HS characteristics correlate with SES. METHODS: For this multicenter cross-sectional reference study, data were collected from patients with HS and sex- and age-matched dermatologic patients in a 1:2 ratio. SES was derived from the mean household income and real estate value on a neighborhood level. RESULTS: The SES distribution among 1018 patients with HS was significantly lower than among 2039 age- and sex-matched dermatologic control patients (P < .001). In patients with HS a low SES was associated with axillary involvement (odds ratio 1.42, P = .04), high body mass index (odds ratio 1.03, P = .003), and lower age at inclusion (odds ratio 0.98, P = .001), but not with disease severity or age of disease onset. LIMITATIONS: SES was based on postal code level and causality cannot be determined. CONCLUSION: In the general population, low SES is associated with an unhealthy lifestyle such as smoking and obesity. Therefore, low SES might be a risk factor for developing HS.

The ABC of Hidradenitis Suppurativa: A Validated Glossary on how to Name Lesions.

BACKGROUND: The precise clinical description of skin lesions observed in some patients with hidradenitis suppurativa (HS) can be extremely difficult. OBJECTIVE: Establishing a validated glossary of terms allowing the best possible description of lesions observed in HS patients. MATERIAL AND METHODS: Five international experts of HS were to assess a series of 25 photos representing typical lesions of this disorder. For each photo, the experts were asked whether naming of the lesions was possible or not and, if yes, by using which noun. Agreement of their responses was calculated using Fleiss's kappa index. Using a Delphi strategy, photos with disagreement were discussed, and photos were reevaluated on the next day. In case of agreement on the impossibility of naming some clinical situations, new terms, to be included into the glossary, were agreed upon. RESULTS: After the first round of photos, agreement between the experts was poor with a kappa index of only 0.33 (95% CI 0.22-0.46). After extensive discussion of cases with disagreement, the kappa index increased on day 2 to 0.75 (95% CI 0.60-0.87), allowing to conclude on good interobserver agreement on terminology. Furthermore, a few clinical situations were identified in which naming with established semantics is so far not possible. For these situations, the terms 'multicord', 'multipore', 'multitunnel' and 'retraction' were defined. DISCUSSION: This is the first validation of clinical terms used to describe lesions in patients with HS. This should be helpful in better defining the clinical phenotypes observed in this disorder.

Boils at Frictional Locations in a Patient with Hidradenitis Suppurativa.

Dear Editor, Hidradenitis suppurativa (HS) is a chronic, recurrent, inflammatory skin disease. The primary clinical presentation are painful inflamed nodules or boils of inverse areas, i.e. the axillary and anogenito-crural regions, but it can also involve the infra- and inter-mammary regions (1,2). The etiology of HS is not clearly defined. Obesity, smoking, and genetic factors are considered important risk factors. In addition, it has also been suggested that friction may contribute to the development of HS, especially in the obese, but this is based on highly anecdotal reports (3-5). We describe a case with classic HS, obesity, and HS-like lesions at the position of the bra strap, suggesting that mechanical stress was an external pathogenic factor for HS development. A 33-year old woman presented with an 18-year history of chronic, recurrent, inflammatory nodules in the axillae, the groin, the pubic region, and to a lesser extent the abdomen and buttocks. She was obese with as result of 33.2 kg/m-2 of 33.2, had a positive family history of two first grade family members with HS, and was a smoker (19 Pack years). There were no other known comorbidities. The inflamed lesions had been treated with several courses of oral antibiotics (minocycline, erythromycin, and combination therapy of clindamycin and rifampicine) and surgical treatments: lancing, deroofing, and excisions (2,6). On examination, there were nodules, folliculitis, cysts, and depressed scars in the axillae and groins, including the inner thighs (Figure 1). On the chest, corresponding to where the lower edge of the patient's bra was usually located, a superficial nodule and follicular papules were observed, exactly coinciding with the red stripe caused by mechanical stress (friction and pressure) of the bra edge. There was no skin fold present on the location of the HS lesions, and there were no lesions observed in the intermammary region or on the side of the breasts in contact with the skin of the thorax (skin to skin contact) (Figure 2). Cultures from skin swabs showed commensal skin flora and moderate mixed anaerobic bacteria, as would be expected in a HS lesion. It is well documented that HS is a disease of the obese. However, the role of friction as an environmental factor is poorly documented. Patients report that environmental factors such as tight-fitting clothing or friction could cause flares in the disease (2). Furthermore, it has been postulated that friction may contribute to the development of HS by stimulating interfollicular hyperplasia (7). HS lesions arranged in a linear pattern suggest an environmental influence and suggests an etiopathogenic role for mechanical stress. Waistline, or as in this case the chest line, distribution indicates that wearing of tight waistbands, wide belts, or bras may induce HS in predisposed individuals. To our knowledge, there is only one case report describing an obese patient with classic HS (typical lesions in predilection areas) who developed HS like lesions on the upper abdomen (waist) at the height of the waistband as well as under the lower abdominal apron (skin on skin contact) (8). Two other reports suggesting a pathogenic role for mechanical stress are flawed, however, as neither of the cases showed signs of concomitant classic HS or had a family history, bringing into question the implied association of HS (9,10). In summary, we presented a case with classic HS locations (typical lesions on typical locations, i.e. the axillae and inguino-crural regions) developing inflammatory lesions on the chest at the location closely corresponding to where the bra strap was exerting mechanical pressure and friction on the skin. The lesions were clinically and microbiologically compatible with ectopic HS lesions. The chest is an atypical HS location free of apocrine sweat glands. It is postulated that these lesions may have been induced by mechanical stress, additionally triggered by the pro-inflammatory state of the obese body. Patients are encouraged to avoid friction from environmental factors such as tight clothing.