ImportanceHidradenitis suppurativa (HS) is associated with considerable diagnostic delay. Although most patients report adolescent onset, existing HS diagnostic criteria may not adequately capture disease in pediatric populations.ObjectivesTo determine the proportion of physician-diagnosed pediatric patients with HS who met diagnostic criteria, and describe demographics, disease characteristics, and diagnostic patterns among pediatric patients with HS.Design, Setting, and ParticipantsIn this retrospective, cross-sectional study, electronic medical records from 2 sites of a single academic tertiary care center were included. Eligible patients were those born after January 1, 1993, and assigned International Classification of Diseases, Ninth and Tenth Revisions (ICD-9/10) codes for HS (ICD-9 705.83/ICD-10 L73.2) between January 1, 2012, and July 1, 2021. Patients were excluded if they were older than 18 years at diagnosis, had inaccessible diagnostic visit notes, or were unintentionally assigned an HS ICD code.ExposuresPediatric patients with HS.Main Outcomes and MeasuresFulfillment of diagnostic criteria in pediatric patients with HS.ResultsA total of 297 adolescents with HS were included in the study; 123 patients were female (78.1%), 78 self-identified as Black (26.3%), and 116 self-identified as Hispanic (39.1%). The median (IQR) age at diagnosis was 14.0 (13.0-16.0) years. Documentation from the diagnostic visit demonstrated that 127 (42.8%) patients did not meet all 3 major HS diagnostic criteria. Of these patients, 122 (96.1%) did not meet the recurrence interval criterion (≥2 lesions within 6 months). Overall, 96 patients who did not meet the recurrence interval criterion had documentation from additional visits in the health system; 59 (61.5%) had documentation of 1 or more additional lesions consistent with HS. Review of these additional records demonstrated that 26 of these 59 (44.1%) patients met the recurrence interval criterion after diagnosis, and 44 (74.6%) had recurrent lesions within a 1-year interval (median, 6.5 months; interquartile range, 3.5-12.2 months). Medical chart review was conducted from November 22, 2021, to January 12, 2022. Analysis was conducted from January 12, 2022, to January 15, 2022.Conclusions and RelevanceOverall, 118 (40%) of 297 pediatric patients with HS in this retrospective cross-sectional study did not meet all major diagnostic criteria at the time of diagnosis, largely due to failure to fulfill the 6-month recurrence interval criterion. Future studies are needed to determine the appropriate recurrence interval to facilitate timely diagnosis and promote clinical trial eligibility for pediatric patients with HS.