Unusual presentation of gout: intratendinous tophus in the patellar tendon.
The gold standard for diagnosis of gout is presence of monosodium urate crystals in tophi or aspirated fluid. (1) Accurate classification of gout without crystal documentation is needed where synovial fluid aspiration cannot be performed. These issues led the international collaborative working group -American College of Rheumatology/European League Against Rheumatism- to develop new classification criteria. (6) The entry criterion requires one episode of joint/ bursa swelling, pain, and tenderness. Presence of monosodium urate crystals is sufficient for diagnosis. The domains of this classification include clinical, laboratory, and imaging criteria like pattern of joint/bursa involvement, serum urate levels, radiographic gout related erosions, urate on dual-energy computed tomography (DECT), or double contour sign on ultrasound. Patient refused aspiration biopsy and DECT for the patellar lesion owing to his previous experiences and met the
[FIGURE 1 OMITTED]
American College of Rheumatology/European League Against Rheumatism gout classification criteria scoring 17/23.
Magnetic resonance imaging is highly sensitive in demonstrating extent and distribution of crystal deposits and differentiates tophi from benign and malignant neoplastic processes and infections. (1,7,8)
[FIGURE 2 OMITTED]
Computed tomography is very sensitive in identifying characteristic erosions and demonstrating the density of tophi as 170 Hounsfield units. (7) DECT shows uniquely color coded aggregates of urate crystals and differentiates gout from other arthritides like rheumatoid arthritis, pseudo-gout, and pigmented villonodular synovitis in the acute phase. (2,6,8,9) Monosodium urate crystals may preferentially deposit on hyaline cartilage giving "double contour sign" on ultrasound and this sign is suggested to be seen even before the development of erosive changes. A distinctly different pattern is present in pseudo-gout where crystal deposition is seen within the cartilage rather than the surface. (7,10) Synovitis in gout tends to show concentric hyperechogenity unlike the frond-like synovial hypertrophy noted in rheumatoid arthritis. (7)
Diagnosing gout using imaging modalities varies in terms of demonstrating deposits as well as the extent and distribution of tophi in various stages of gout. The 2015 American College of Rheumatology/European League Against Rheumatism classification criteria represent an advance over previous guidelines, with improved performance characteristics and incorporation of newer imaging modalities, namely ultrasound and DECT. Our case shows the possibility of gout involvement of quite a rare site such as the patellar tendon and underlines the importance of early diagnosis with advanced imaging modalities to facilitate management of disease.
Declaration of conflicting interests
The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.
The authors received no financial support for the research and/or authorship of this article.
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Canan CIMSIT, Onur BUGDAYCI, Mustafa Erkin ARIBAL
Department of Radiology, Marmara University Pendik Training and Research Hospital, Istanbul, Turkey
Received: September 30, 2015 Accepted: October 01, 2015 Published online: November 02, 2015
Correspondence: Canan Cimsit, MD. Marmara Oniversitesi Pendik Egitim ve Arastirma Hastanesi Radyoloji Anabilim Dali, 34890 Ost Kaynarca, Pendik, istanbul, Turkey. Tel: +90 532-570 73 87 e-mail: firstname.lastname@example.org
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|Author:||Cimsit, Canan; Bugdayci, Onur; Aribal, Mustafa Erkin|
|Publication:||Turkish Journal of Rheumatology|
|Article Type:||Letter to the editor|
|Date:||Mar 1, 2016|
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