The manifestations of psoriatic arthropathy (PsA) in joints have been extensively described.1 The use of high-resolution ultrasound in this disease is more recent and the findings are similar to those observed in other inflammatory diseases, like rheumatoid arthritis (RA)2,3 and lupus.4 Some of these ultrasound findings in joints are suggestive of acute inflammatory activity in PsA and in psoriasis (enthesitis, dactylitis), whereas others are less common, among them, acute tenosynovitis of the flexor tendon, detected by high-resolution ultrasound in only 0.3%–7% of cases.1,2,5

We report the case of a 37-year-old man with PsA that began in 2003 with skin involvement, and eventually affected his joints. He started taking methotrexate in 2014, and is currently in clinical remission. At his last check-up, his cutaneous condition had worsened and he complained of apparently mechanical pain in the fourth finger of his right hand. Clinical examination found nothing of interest, whereas ultrasound revealed acute tenosynovitis of the flexor tendon in that finger, affecting the entire volar portion (Fig. 1). The clinical signs remitted after ultrasound-guided corticosteroid injection.

Fig. 1.

Ultrasound images of the 4th finger of the patient's right hand. (A) Long-axis view of middle-distal phalanges, with grade 1 power Doppler signal. (B) Long-axis view of proximal phalanx-metacarpus, with grade 2 power Doppler signal. (C) Cross-sectional view of proximal phalanx-metacarpus, with grade 2 power Doppler signal.

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The purpose of this report is to reflect the importance of ultrasound, not only in the management of RA, but also in the monitoring and follow-up of PsA in clinical remission, and to illustrate ultrasound monitoring of these patients. We wish to point out that acute tenosynovitis of the flexor tendon of the hand often goes unnoticed, but may be more common than is reported in patients with disease of low inflammatory activity.6