BackgroundThe mean age of onset of hidradenitis suppurativa (HS) is between 20 and 24years. Very few data about patients with early-onset HS exist. ObjectiveTo investigate the association of early-onset HS with the clinical characteristics: age, gender, body mass index (BMI), smoking, family history of HS, Hurley stage, and number of areas affected. MethodsThis was a retrospective study of the reported early age at HS onset (17years old) with clinical characteristics and with the severity of HS at first consultation visit. ResultsIn 166 patients, 42 patients (25.3%) reported early-onset HS. Compared to adult-onset HS, patients with early-onset HS were younger (mean age: 37years vs. 27years, P<0.0001), had a significantly younger mean age of onset (28.2years old vs. 14.5years old, respectively, P<0.0001), longer mean disease duration (8.8years vs. 12.6years, respectively, P=0.011) and were less frequently smokers (P<0.001), whereas there was no association with gender (P=0.177) or BMI (0.086). Patients with a family history had increased risk for early-onset HS (OR: 2.45, 95% CI: 1.08-5.56). Early-onset HS was not associated with Hurley stage (OR: 1.12, 95% CI: 0.33-3.74) or with the number of body areas affected (OR: 1.54, 95% CI: 0.49-4.83). ConclusionEarly-onset HS was frequent and associated with a family history of HS. There was no difference in the severity of HS in adult life for patients with an onset of HS at 17years, compared to patients with adult-onset, which may be reassuring information for these younger patients.