tophus

Etiology

• may occur in gout
• may refer to sialolithiasis

Pathology

• avascular deposit of uric acid in periarticular fibrous tissue, cartilage of the external ear or kidney
• chalky white masses of uric acid, surrounded by inflammatory cells & fibrous tissue.

Clinical manifestations

• painless, persistent, generally noninflammatory nodules
• many be palpable on physical examination
• may occur within joints or non-palpable tissues
  • located around joints & in soft tissues
  • predilection for the extensor surfaces of the
    • elbows
    • distal Achilles tendon
    • fingers (proximal interphalangeal joints & distal interphalangeal joints)
    • cartilaginous portions of the ears.
• acute gouty flares may occur at sites of tophi

Radiology

• X-ray of affected joint(s)
  • tophi appear as hyperdense soft tissue swellings
    • calcifications may appear within tophi
• ultrasound is the most sensitive method to detect tophi

Complications

• tophi are deforming, can interfere with function, & directly erode bone
• ulceration of overlying skin can occur
  • infection can be difficult to treat because tophi are avascular

Differential diagnosis

• arthritis mutilans

Management

• see gout

More general terms

• gout
• abnormal morphologic structure (malformation)

Additional terms

• sialolithiasis (salivary stone)