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Dactylitis is diffuse swelling of an entire finger or toe (“sausage digit”), involving the soft tissues, synovium, tendon sheaths, and sometimes bone. It is not a disease itself but a clinical/radiological sign seen in various inflammatory, infectious, and infiltrative disorders.

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Etiopathogenesis

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Dactylitis results from inflammation of flexor tendon sheaths (tenosynovitis), synovium, and periarticular soft tissues, sometimes with bone involvement.

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Mechanisms differ by cause:

Inflammatory arthropathies: synovitis, enthesitis, and tenosynovitis (e.g., psoriatic arthritis, reactive arthritis).
Granulomatous/infiltrative: sarcoidosis, amyloidosis, gout.
Infective: tuberculous or syphilitic dactylitis, bacterial osteomyelitis.
Vaso-occlusive: sickle cell disease (infarction of marrow and bone).

Common Causes of Dactylitis

Domain	Etiology
Inflammatory / Rheumatologic	• Psoriatic arthritis (most common cause in adults).
• Reactive arthritis.
• Other seronegative spondyloarthropathies.
Hematologic	Sickle cell disease: especially in children <6 yrs, painful hand-foot syndrome.
Infectious	• Tuberculosis → spina ventosa.
• Syphilis (congenital).
• Pyogenic osteomyelitis.
Granulomatous / Infiltrative	• Sarcoidosis.
• Amyloidosis.
• Gout (tophaceous deposits).

Different types of dactylitis with the involved tissues: https://doi.org/10.1080/03009740600906677

Type of dactylitis	Type of involvement
Tuberculous dactylitis	Osteomyelitis extending to digit soft tissue
Syphilitic dactylitis	Osteomyelitis
Sarcoid dactylitis	Non‐caseating granulomas invading the phalanges and adjacent soft tissue
Blistering distal dactylitis	Infection of the anterior fat pad of the volar surface of the distal part of the finger or toe
Sickle cell disease dactylitis	Infarction of bone marrow
Spondyloarthritis dactylitis	Flexor tenosynovitis

Clinical Features

Fusiform, uniform swelling of entire digit (finger or toe).
Tenderness, erythema, warmth (in acute inflammation).
Often painful with limited movement.
May be unilateral or bilateral, single or multiple digits.

Associated systemic/primary disease clues: