Dactylitis

Dactylitis is the diffuse swelling of an entire finger or toe, sometimes referred to as a sausage digit. It results from inflammation of soft tissues and, in some conditions, bone. Clinically it presents as a painful, swollen digit with limited motion, often without a discrete focal joint swelling.

Causes vary by age. In children, dactylitis is a common manifestation of juvenile idiopathic arthritis and may also occur with sickle cell disease (hand-foot syndrome). In adults, it is frequently associated with psoriatic arthritis and other spondyloarthropathies; less commonly with gout, infection, reactive arthritis, or trauma.

Pathophysiology differs by cause. In sickle cell disease, vaso-occlusion triggers inflammation and edema of the digit. In inflammatory arthritides such as psoriatic arthritis, dactylitis reflects combined synovitis, tenosynovitis, and enthesitis leading to diffuse digit swelling. Nail changes and psoriasis may accompany psoriatic disease.

Diagnosis is mainly clinical, aided by imaging and laboratory studies to define etiology. Ultrasound or MRI can show synovitis and tenosynovitis; X-ray may be normal early but can reveal chronic changes. Treatment targets the underlying condition: analgesia and hydration for sickle cell crises; NSAIDs, corticosteroids, and disease-modifying therapies for inflammatory arthritis. Prognosis depends on the underlying disease and response to therapy.