Pediatric-onset hidradenitis suppurativa: a case series of 42 patients.

The aim of the study was to review the clinical and demographic characteristics of pediatric-onset HS patients.

Hidradenitis suppurativa (HS) is a chronic, recurrent skin condition characterized by inflammation of the terminal hair follicle, leading to painful, deep-seated lesions, including nodules, fistulas, abscesses, and scarring. The prevalence of HS ranges from approximately 0.05% to 4.10%, with the peak incidence typically occurring in the second or third decade of life [ 1 ]. It disproportionately affects women (3 : 1 ratio) and exhibits a notable racial component, primarily impacting the Caucasian race [ 2 ]. The clinical diagnosis of HS relies on recognizing characteristic lesions, their location in skin folds, and the chronic nature of the disease. Numerous comorbidities have been linked to HS, such as acne vulgaris, depression, polycystic ovary syndrome, dissecting cellulitis of the scalp, and metabolic syndrome [ 3 ]. The pathomechanism of the disease is intricate and not fully understood. Genetics are believed to play a central role in disease development, often in conjunction with environmental, hormonal, and microbiological factors [ 4 ]. Proinflammatory cytokines and chemokines, such as tumor necrosis factor-α (TNF-α), interferon-γ (IFN)-γ, interleukin (IL)-17, IL-26, and IL-1, are implicated in the pathogenesis of HS [ 5 ]. Pediatric-onset HS poses a challenge, with many patients receiving off-label drugs of varying effectiveness. Treatment recommendations are derived from therapeutic consensus guidelines, clinical practice, and case series reports. The primary treatment approach depends largely on disease severity, encompassing topical and systemic antibiotics, retinoids, and surgical interventions [ 4 ]. Currently, adalimumab, a human IgG1 monoclonal antibody selectively targeting TNF-α, is the only FDA-approved biologic for moderate to severe HS [ 6 ]. Other biologics, including TNFa-inhibitors and IL-17 antibodies, show promise [ 7 , 8 ]. Ongoing clinical trials are investigating new potential drugs for HS, such as oral upadacitinib and povorcitinib (selective JAK1 inhibitors), topical ruxolitinib (a JAK1/JAK2 inhibitor), and spesolimab (an interleukin-36 receptor antagonist). The complex pathogenesis and the current lack of highly effective HS treatments underscore the necessity for ongoing research to identify new therapeutic targets and better understand the disease’s pathomechanism.

This study included a total of 42 patients diagnosed with HS who were aged < 18 years at the time of diagnosis. The median age of onset among our patients was 14 years, with a range of 5 to 17 years. The cohort comprised 20 (48%) males and 22 (52%) females. The youngest reported age was 5 years, and the oldest was 17 years. All patients identified as Caucasian. Detailed demographic information and family history of the study population are presented in Table 1 . Patient demographics Among the 42 patients, 16 (38%) presented with a severe stage of the disease at the time of diagnosis (Hurley III), 17 (40%) exhibited a moderate stage (Hurley II), and 9 (21%) had a mild stage (Hurley I). Details of disease activity are outlined in Table 2 . Disease activity Lesions in our patients primarily manifested in typical HS skin areas. Inguinal folds were the most frequently affected, observed in 35 of 42 (83%) patients, followed closely by lesions in the armpits, documented in 32 of 42 (76%) patients. Other common locations included the lower abdomen, buttocks, chest, and perianal area ( Table 2 ). Notably, lesions in the genital area were more prevalent in females than in males. Overall, comorbidities were present in 32 (76%) of the 42 patients. The most common were obesity and affective disorders, reported in 18 (43%) and 10 (24%) patients, respectively. Other frequent comorbidities included overweight in 9 (21%), acne vulgaris in 7 (17%), and hypothyroidism in 7 (17%) of patients ( Table 3 ). Frequency of comorbidities and laboratory findings In addition to skin lesions and comorbidities, laboratory findings were documented. Differences were observed in levels of aminotransferases, total, low-density lipoproteins (LDL), and high-density lipoproteins (HDL) cholesterol, platelet counts, and serum C-reactive protein (CRP) levels, which were elevated. Conversely, reduced values were noted for erythrocyte counts, haemoglobin levels, and mean corpuscular volume (MCV) ( Table 3 ). The treatment approach for HS depends on the morphology, extent, severity, and duration of the disease. Lesion management in our patients involved either medications or surgical excisions, with the majority undergoing a combination of treatments. A comprehensive list of treatment methods utilized in our patients is provided in Table 4 . Management In cases of mild HS (Hurley I), topical clindamycin was the primary treatment for 8 out of 9 (89%) patients, with effectiveness observed in 2 of 9 (22%) cases. For those in whom topical methods proved insufficient, initiation of systemic treatment became necessary. For moderate to severe forms of HS, oral retinoids or antibiotics were incorporated into the treatment regimen. The choice of treatment method depended largely on the results of laboratory tests and the patient’s age. The teratogenic potential of oral retinoids, particularly for women of reproductive age, was a significant consideration. In our cohort, males exclusively received acitretin, a second-generation retinoid, while isotretinoin, a first-generation retinoid with a shorter elimination half-life, was prescribed to both females and males. Among the antibiotic therapies, a combination of oral clindamycin and rifampicin was most commonly prescribed, administered to 34 out of 42 (81%) patients. Other frequently used antibiotics included lymecycline (7/42, 17%), trimethoprim with sulfamethoxazole (6/42, 14%), and amoxicillin with clavulanic acid (6/42, 14%). Of the 42 patients with pediatric-onset HS, 17 (40%) received biologic treatment. TNF-α inhibitors, particularly adalimumab (8 patients) and infliximab (6 patients), were the primary biologics used, with most patients experiencing satisfactory improvement. Two patients received secukinumab, a human monoclonal anti-IL-17A antibody, administered subcutaneously every 2 weeks, showing promising results. Ongoing clinical studies, including some at our centre (Department of Dermatology, National Medical Institute of the Ministry of the Interior and Administration, Warsaw, Poland), provided access to innovative treatment methods resulting in significant improvements in the severity of skin lesions for 6 of our patients. Surgical procedures, such as the removal of fistulas and abscesses, are essential in addressing the primary causes of disease progression, significantly contributing to pain reduction and long-term lesion resolution.

The objective of this case series is to explore the prevalence, demographic and clinical features, as well as the management of pediatric-onset HS. We anticipate that our findings will assist other physicians in the effective management of pediatric patients with HS, highlighting crucial aspects for consideration in daily clinical practice. Our study results align closely with those reported in other series. Similar to adult-onset HS, we observed a female preponderance, although without significant distinction. The location of lesions in pediatric-onset HS corresponds to the areas affected in adult-onset HS [ 9 ]. There exists a notable correlation between an elevated body mass index (BMI) and the development of HS lesions [ 10 ]. Our study also affirms the influence of obesity on the heightened risk of HS, with 27 out of 42 (64%) patients exhibiting an increased BMI (> 25 kg/m 2 ). This emphasizes the role of obesity in disease progression, persistence of HS lesions, and impaired wound healing. Consistent with prior research, our study identified common comorbidities such as acne vulgaris, depression, and obesity [ 3 ]. The emotional impact of the disease and the high prevalence of affective disorders among our patients were significant, mirroring findings reported in other studies [ 11 ]. Skin lesions and the chronic pain associated with them often hinder patients’ daily functioning, leading to a substantial reduction in the quality of life. This, in turn, may trigger permanent mood disorders, sleep deprivation, and depressive episodes. Hence, it is crucial to provide patients with appropriate treatment and psychological support when necessary. Our case series reinforces the vital role of biologics, illustrating their efficacy and safety in HS treatment. Limitations of this case series include its retrospective nature and the inclusion of patients from only two hospitals, potentially limiting the generalizability of HS treatment results in Poland. Additionally, due to the frequent absence of complete treatment documentation before patients are admitted to our departments, the listed treatment methods may be incomplete.

This case series stands as the largest collection of patients summarizing the clinical presentations and management of pediatric-onset HS in Poland. Given the chronic nature of the disease, future studies are warranted, with a focus on treatment response and the quality of life in patients with pediatric-onset HS.

The study comprised 42 patients diagnosed with HS, aged ≤ 18 years at the time of diagnosis, and admitted to the Department of Dermatology, National Medical Institute of the Ministry of the Interior and Administration in Warsaw, Poland and the Department of Dermatology, Venereology, and Allergology at the Medical University of Gdansk, from January 2000 to May 2023. Written informed consent for the publication of patients’ clinical details was obtained. Patients’ records were retrospectively examined using the hospital’s electronic records. Inclusion criteria encompassed a diagnosis of HS established before the age of 18. A comprehensive review of clinical information, including the disease’s clinical course, the affected anatomical area, past medical history, demographic details (age at onset, ethnicity, gender, family history of HS), comorbidities, and laboratory findings, was conducted via a retrospective chart review. All cases underwent assessment based on HS criteria, utilizing the Hurley staging system to categorize the extent of disease (Stage I: abscess formation, no sinus tracts or cicatrisation; Stage II: recurrent abscesses with sinus tracts and cicatrisation; Stage III: diffuse or almost diffuse involvement, or multiple interconnected sinus tracts and abscesses). Exclusion criteria were applied to patients who did not meet these specified criteria. Statistical analyses were carried out using Microsoft Excel 97-2003 (Microsoft, USA).