Sonographic features of a tophaceous nodule.

• Vol 7 • November 2005 746 Subcutaneous nodules with prominent inflammatory features are a diagnostic challenge [1]. The differential diagnosis includes ganglion, cyst, space-occupying lesion, tenosynovitis, rheumatoid nodule, infection, and tophaceous nodule. An imaging technique that could specifically demonstrate monosodium urate deposits within tissues can be extremely helpful, especially in patients presenting with swelling of soft tissues or nodules of unknown causes. On Doppler ultrasonography, the tophi appear as attenuating hypoechogenic structures with shadowing and hypervascularity representing inflammation, surrounded by hyperechogenic tissue [2]. These findings cannot be considered specific for gout as they resemble rheumatoid nodules, but are different from those of abscess or fluid collection [2]. We describe a patient who developed a painful, red, warm swelling above the second and third metacarpophalangeal joints. The Doppler ultrasound (SonositeTitan, Linear transducer L38 with a frequency 5–10 broad band MHz) examination allowed us to differentiate the lesion from an abscess or joint effusion, and to suggest gouty tophi.