•Patients’ tophus volume ranged from 0.63 cm3 to 249.13 cm3 (slightly larger than a baseball), with a mean of 40.20 cm3 (about the size of a golf ball). Only joints were scanned.20
Tophi start as nonvisible clusters of uric acid crystals that can deposit almost anywhere.9
Dual-energy computed tomography (DECT) and ultrasound scanning studies found nonvisible tophi in the majority of patients4,10
•In a prospective DECT study, Bongartz et al demonstrated urate crystal deposition in 95% of patients with gout (N=40)10
•Patient population specifically excluded those with visible tophi10
•Thiele et al found ultrasound evidence of tophi in all patients with gouty hands and feet (N=23)4a
oNonvisible tophi: 59% (13/22)
oVisible tophi: 41% (9/22)
•0% (0/23) of patients in the control group had evidence of tophi
aTophi status for 1 patient was not recorded to be either nonvisible or visible.
more urate deposits were found using DECT vs through clinical examination.20*
*In a study evaluating the utility of DECT scanning in assessing urate deposits in gout patients (N=20).20
CHRONIC INFLAMMATION INDUCED BY URATE CRYSTAL DEPOSITION CAN LEAD TO JOINT DAMAGE5,19
Imaging highlights the links between urate crystal deposition, tophus formation, the resulting inflammation, and bone erosion5,19
T1-weighted coronal image showing multiple erosions, with a large lesion at the distal ulna (circle).19
T1-weighted axial image confirming erosion and tophus.19
Images used with permission of McQueen F et al. Rheumatology. 2014;53:95-103.19 Individual presentation may vary.
In an ultrasound study, bone erosions adjacent to tophaceous material were seen in 65% of metatarsophalangeal joints and 25% of metacarpophalangeal joint4
•Patients both with and without visible tophi were found to have bone erosions
Cartilage damage and loss are also observed around tophi22
•MRI scans have shown that cartilage damage is predominantly focal and related to sites of tophi
oIn addition to tophi, cartilage damage was associated with synovitis and bone erosion
•Tophus infiltration into bone may be accompanied by damage to the overlying cartilage†
†Based on an uncontrolled MRI imaging study of wrists in 40 gout patients.
- Baraf HS, Becker MA, Gutierrez-Urena SR, et al. Tophus burden reduction with pegloticase: results from phase 3 randomized trials and open-label extension in patients with chronic gout refractory to conventional therapy. Arthritis Res Ther. 2013;15(5):R137.
- Sundy JS, Baraf HS, Yood RA, et al. Efficacy and tolerability of pegloticase for the treatment of chronic gout in patients refractory to conventional treatment: two randomized controlled trials. JAMA. 2011;306(7):711-720.
- KRYSTEXXA [prescribing information]. Horizon Pharma Rheumatology LLC. September 2016.
- Thiele RG, Schlesinger N. Diagnosis of gout by ultrasound. Rheumatology (Oxford). 2007;46(7):1116-1121.
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- Naredo E, Uson J, Jiménez-Palop M, et al. Ultrasound-detected musculoskeletal urate crystal deposition: which joints and what findings should be assessed for diagnosing gout? Ann Rheum Dis. 2014;73(8):1522-1528.
- Dalbeth N, House ME, Horne A, Taylor WJ. Reduced creatinine clearance is associated with early development of subcutaneous tophi in people with gout. BMC Musculoskelet Disord. 2013;14:363.
- Dalbeth N, Pool B, Gamble GD, et al. Cellular characterization of the gouty tophus: a quantitative analysis. Arthritis Rheum. 2010;62(5):1549-1556.
- Doghramji PP, Wortmann RL. Hyperuricemia and gout: new concepts in diagnosis and management. Postgrad Med. 2012;124(6):98-109.
- Bongartz T, Glazebrook KN, Kavros SJ, et al. Dual-energy CT for the diagnosis of gout: an accuracy and diagnostic yield study. Ann Rheum Dis. 2015;74(6):1072-1077.
- Schett G, Schauer C, Hoffmann M, Hermann M. Why does the gout attack stop? A roadmap for the immune pathogenesis of gout. RMD Open. 2015;1:(suppl 1):e000046.
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- Edwards NL. Crystal-induced joint disease. In: Nabel EG. ACP Medicine: A Publication of the American College of Physicians. Hamilton, Ontario: Decker Intellectual Properties; 2012:1-16.
- Yu KH, Lien LC, Ho HH. Limited knee joint range of motion due to invisible gouty tophi. Rheumatology (Oxford). 2004;43(2):191-194.
- Dalakas MC. Inflammatory muscle diseases. N Engl J Med. 2015;372:1734-1747.
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- McQueen FM, Doyle A, Reeves Q, et al. Bone erosions in patients with chronic gouty arthropathy are associated with tophi but not bone oedema or synovitis: new insights from a 3 T MRI study. Rheumatology (Oxford). 2014;53(1):95-103.
- Choi HK, Al-Arfaj AM, Eftekhari A, et al. Dual energy computed tomography in tophaceous gout. Ann Rheum Dis. 2009;68(10):1609-1612.
- Park JJ, Roudier MP, Soman D, Mokadam NA, Simkin PA. Prevalence of birefringent crystals in cardiac and prostatic tissues, an observational study. BMJ Open. 2014;4(7):e005308.
- Popovich I, Dalbeth N, Doyle A, Reeves Q, McQueen FM. Exploring cartilage damage in gout using 3-TMRI: distribution and associations with joint inflammation and tophus deposition. Skeletal Radiol. 2014;43(7):917-924.
- Khanna D, Fitzgerald JD, Khanna PP, et al. 2012 American College of Rheumatology guidelines for management of gout. Part 1: systematic nonpharmacologic and pharmacologic therapeutic approaches to hyperuricemia. Arthritis Care Res (Hoboken). 2012;64(10):1431-1446.
- Perez-Ruiz F. Treating to target: a strategy to cure gout. Rheumatology (Oxford). 2009;48(suppl 2):ii9–ii14.
- Araujo EG, Bayat S, Petsch C, et al. Tophus resolution with pegloticase; a prospective dual-energy CT study. RMD Open. 2015;1(1):e000075.
- Schumacher HR, Becker MA, Wortmann RL, et al. Effects of febuxostat versus allopurinol and placebo in reducing serum urate in subjects with hyperuricemia and gout: a 28-week, phase III, randomized, double-blind, parallel-group trial. Arthritis Rheum. 2008;59(11):1540-1548.
- Data on file. Horizon Pharma Rheumatology LLC; 2016.
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