Arthritis Mutilans: A Devastating Manifestation of Psoriatic Disease Without Dactylitis in a 61-Year-Old Patient.

Arthritis mutilans (AM) is the most severe and least common form of psoriatic arthritis (PsA), characterized by digital shortening due to osteolysis and often associated with profound functional disability. We report a case of a 61-year-old male with longstanding plaque psoriasis and poor treatment adherence who developed AM affecting the interphalangeal joints of the left foot, with significant joint deformity and extensive skin involvement (30% body surface area). Imaging revealed severe bone breakdown, leading to the affected phalanges of the foot appearing shortened or telescoped. AM typically presents in patients with distal interphalangeal joint involvement and is often linked to a history of dactylitis. Although rare, it can also appear in other rheumatic conditions, including rheumatoid arthritis and systemic lupus erythematosus. Current challenges include the absence of standardized phenotypic definitions and a limited understanding of clinical predictors. Early identification of at-risk patients is critical to prevent irreversible joint damage and disability.