Hidradenitis Suppurativa (HS) is a chronic inflammatory skin disease manifesting in painful inflamed nodules abscesses and malodourous draining epithelialised dermal tunnels ( Frew et al., 2021 Frew JW, Marzano AV, Wolk K, Join-Lambert O, Alavi A, Lowes MA, Piguet V. A Systematic Review of Promising Therapeutic Targets in Hidradenitis Suppurativa: A Critical Evaluation of Mechanistic and Clinical Relevance. J Invest Dermatol. 2021 Feb;141(2):316-324.e2 Google Scholar ) with an estimated prevalence of 1% of the general population. The past five years have seen a dramatic expansion in the number of clinical trials, basic and translational investigation in the disease. In contrast to psoriasis vulgaris and atopic dermatitis, HS is a highly heterogeneous disease. Heterogeneity manifests both morphologically (with the differing types of lesions (ie nodule, abscesses and tunnels) as well as immunologically. ( Navrazhina et al., 2021 Navrazhina K. Garcet S. Gonzales J. Grand D. Frew J.W. Krueger J.G. In-Depth Analysis of the Hidradenitis Suppurativa Serum Proteome Identified Distinct Inflammatory Subtypes. J Invest Dermatol. 2021; https://doi.org/10.1016/j.jid.2021.02.742 Abstract Full Text Full Text PDF Scopus (19) Google Scholar ). We still have an incomplete understanding of the immunological mechanisms of disease, particularly how these mechanisms and characteristic differ in moderate versus severe disease.