[The hand: a reflection of arthritis].

Hand joint involvement in rheumatic diseases is often precocious and predominant as compared to other skeleton-muscular regions. Clinical examination not always allows for easy detection of fluid outpouring and synovial involvement, and undoubtedly does not allow to diagnose pathognomonic bone alterations of several rheumatic conditions. Articular ultrasonography is an innocuous methodology, easily reproducible and directly applied by a rheumatologist. The aim of this vignette is to present ultrasonography elementary lesions of the hand for a prompt diagnosis.