Achilles paratendonitis as the initial manifestation of rheumatoid arthritis.

We report a case of rheumatoid arthritis in which the earliest symptom was bilateral paratendonitis of the Achilles tendons, followed by paratendonitis of a finger extensor. A series of musculoskeletal ultrasonograms revealed a progression from paratendonitis of the extensor tendon to erosive synovitis of the adjacent metacarpophalangeal joint. High-resolution ultrasonography combined with power Doppler imaging seems to be a useful and convenient tool both for diagnosing paratendonitis early and for closely monitoring the progressing inflammation.