The wider implications of dactylitis beyond psoriatic arthritis.

Abstract

Dactylitis (from the Greek word dactylos, meaning "digit") is a medical condition commonly known as "sausage digit", referring to the diffuse swelling of a finger or toe. Dactylitis is most commonly associated with the spectrum of spondyloarthritis, particularly psoriatic arthritis (PsA), and more rarely with other inflammatory conditions such as sarcoidosis and gout. In PsA, dactylitis is associated with increased disease severity and radiographic progression, and its recognition may facilitate early diagnosis and timely treatment. In sarcoid disease, dactylitis is clinically relevant, reflecting granulomatous inflammation and potentially indicating multisystem involvement. Although most commonly linked to inflammatory disorders, it may also manifest in a variety of other conditions, such as trauma, congenital deformities, infectious diseases, and neoplastic processes, all of which can present with a clinically indistinguishable phenotype. This review provides a comprehensive, up-to-date overview of dactylitis, beginning with the origin of the term and its earliest historical and scientific references, and concluding with the latest insights into aetiopathogenesis, classification, anatomy, imaging, and therapeutic strategies. Through the integration of clinical knowledge with new developments in imaging, the paper explores how the study of dactylitis can extend beyond PsA.