The role of dermatology within the broader spectrum of immune-mediated inflammatory diseases (IMIDs) has evolved remarkably in recent years. The development and expansion of systemic and advanced therapies, biologic and small-molecule agents, have revealed a much closer interconnection between skin diseases and other chronic inflammatory disorders. Parallel to this therapeutic progress, our understanding of the underlying etiopathogenic mechanisms has deepened. Advances in immunology, genetics, and microbiome research have demonstrated that IMIDs do not exist in isolation; rather, they share common inflammatory cascades involving Th1, Th17, and Th22 pathways, among others. Such progress compels us to refine our conceptual framework, particularly in how we describe and interpret the coexistence of multiple conditions in dermatology. In dermatologic literature, the term comorbidity is widely used but often ambiguously. It is commonly employed to denote both true disease concurrence and epidemiological association. In contrast, other specialties, notably rheumatology 1 and gastroenterology 2, 3, have made deliberate efforts to clarify these concepts through the use of specific terminology. They differentiate between comorbidity (concurrence), defined by Feinstein in 1970 as “any distinct clinical entity that has existed or may occur during the clinical course of a patient with an index disease” 4, and associated comorbidity, which indicates that two or more conditions occur together more frequently than would be expected by chance. Furthermore, this implies that such an association is consistent, reproducible, and supported by solid biological or epidemiological evidence. This refinement has led to expressions such as extraintestinal or musculoskeletal manifestations, which convey pathogenic relationships rather than simple coexistence. Dermatology could benefit from similar precision. The current use of comorbidity in skin diseases often conflates coincidental coexistence with pathogenically linked conditions. Metabolic syndrome or cardiovascular disease in psoriasis are commonly labeled “comorbidities,” although their relationship is primarily associative, albeit supported by shared inflammatory mechanisms. Conversely, conditions such as HS and Crohn's disease share both pathogenic mechanisms and overlapping molecular signatures, representing a more integrated systemic inflammatory process rather than a mere coincidence. In this context, pragmatic operational criteria may help guide classification. Extracutaneous manifestations may be considered when there is evidence of pathogenic integration, reflected by shared molecular or immunologic pathways, consistent epidemiologic association, and convergence in response to targeted therapies. By contrast, cutaneous associations refer to conditions that occur more frequently than expected by chance but for which evidence does not demonstrate an integrated pathogenic mechanism. Extracutaneous manifestations: IMIDs that belong to the same pathogenic spectrum as the primary skin disease. For example, HS is linked to inflammatory bowel disease, with an odds ratio (OR) of 2.12 (95% CI 1.46–3.08) for Crohn's disease and 1.51 (95% CI 1.25–1.82) for ulcerative colitis. Likewise, psoriatic arthritis occurs in up to 24% of patients with psoriasis, representing a true extracutaneous manifestation driven by shared Th17-mediated inflammation 5, 6. Cutaneous associations: Dermatologic conditions that occur more frequently in patients within the course of another cutaneous IMID, supported by epidemiologic or biologic evidence. For instance, psoriasis is associated with HS (OR 3.24; 95% CI 2.27–4.62) 7. This framework would allow dermatologists to communicate more accurately about disease interrelations, improve multidisciplinary collaboration, and enhance our capacity to design studies addressing systemic involvement in skin diseases. Clarifying terminology is not a semantic exercise but a necessary step toward scientific rigor. As our specialty continues to embrace systemic and advanced therapies, dermatologists must align conceptual models with those of related disciplines. In conclusion, adopting extracutaneous manifestations and cutaneous associations would enhance the consistency of dermatologic discourse and align the field with the evolving understanding of IMIDs. Mireia Moreno contributed to the conception of the idea and revision of the manuscript. Patricia Garbayo Salmons contributed to the conception of the idea and was responsible for drafting the manuscript. The authors received no specific funding for this work. The authors have nothing to report. P. Garbayo-Salmons declares honoraria for participating in advisory boards from Novartis; has received speaker's honoraria and/or travel support for attending meetings sponsored by Abbie, Amgen, Lilly, LEO Pharma, Novartis, and UCB. M. Moreno has received consultancy/speaker's/advisory boards honoraria and/or travel support for attending meetings and/or participated in clinical trials sponsored by AbbVie, Amgen, Boehringer Ingelheim, Bristol-Meyers Squibb, Gebro, Johnson & Johnson, Lilly, Novartis, Pfizer and UCB. The data that support the findings of this study are available from the corresponding author upon reasonable request.
Garbayo‐Salmons et al. (Wed,) studied this question.