The Role of Second to Fourth Digit Ratio in Hidradenitis Suppurativa: A Potential Link to Prenatal Hormonal Exposure

Objective: Hidradenitis Suppurativa (HS) is a chronic skin condition marked by inflammation and driven by diverse underlying mechanisms, including hormonal involvement. The second-to-fourth digit ratio (2D:4D) is an established marker of prenatal androgen exposure, which may contribute to HS susceptibility. The objective of this study was to explore the potential link between 2D:4D digit ratios and hidradenitis suppurativa, along with their correlation to disease severity.
Materials and Methods: A total of 140 HS cases and 140 healthy subjects matched by age and gender were enrolled in this cross-sectional investigation. Clinical severity was assessed using Hurley staging, the Modified Sartorius Score, and the Physician Global Assessment (PGA). Finger lengths were measured using a digital caliper, and 2D:4D ratios were calculated separately for each hand.
Results: HS patients had significantly lower 2D:4D ratios in both hands compared with controls (p < 0.001). In females, both left- and right-hand ratios were lower (p < 0.001), while in males only the left-hand ratio differed (p = 0.038). In female patients, the left-hand ratio correlated with disease severity measures, including Hurley stage, Modified Sartorius Score, and PGA (all p < 0.05).
Conclusion: Lower 2D:4D ratios, particularly in female HS patients, may reflect higher prenatal androgen exposure and be linked to greater disease severity. These findings support a possible hormonal contribution to HS pathogenesis, though confirmation in prospective studies with direct hormonal assessment is warranted. Interpretation is limited by the cross-sectional design. Additionally, the single-center setting and absence of biochemical hormone measurements may partly limit generalizability and the strength of disease mechanism–related interpretations.