Background/Purpose:

Musculoskeletal involvement in systemic lupus erythematosus (SLE) is common but poorly characterised with only a few Magnetic Resonance Imaging (MRI) or ultrasound (US) studies to date published in lupus arthritis.   Erosive disease in SLE associated with rheumatoid factor (RF) or anti-CCP antibody (ACPA) is often referred to as ‘rhupus’ to indicate a mixture of the character of RA and lupus.  This study used MRI and US to investigate a cohort of hand and wrist SLE disease in comparison to RA and in respect to autoantibody status.  

Methods:

50 SLE patients (median (IQR) disease duration 15.5 (9,20) yrs) with joint symptoms and /or objective arthritis, and 40 RA patients (median disease duration 15 (5,23) yrs) had a detailed US scan (Grey-scale (GS) and Power Doppler (PD)) of  dominant hand and wrist as per standardised protocols. 34 of these SLE patients and 15 RA patients also had a contrast enhanced MRI of their hand which was scored according to the OMERACT RAMRIS system. Extended antibody analysis (which included the anti-RA33 antibody and ACPA) was performed.

Results:

There were no normal MRI examinations in the SLE group; 85% of MCP joints in lupus patients showed at least Grade 1 synovitis, compared to 76.7% of all RA MCP joints. All SLE wrist joints showed at least Grade 1 synovitis. 61.8% of those SLE patients had MRI determined MCP joint erosion compared to 100% of RA patients.  93.3% had at least one erosion at the wrist with erosions in 45% of the total number (n = 240) of SLE carpal bones.  The prevalence of extensor tenosynovitis on MRI at the wrist was greater in the SLE group (20.3%), than in the rheumatoid group (10.7%) (p = 0.05).

Anti-RA33 titres  correlated with SLE disease activity (SELENA SLEDAI) scores (p = 0.03) but in addition there was a strong negative correlation with total MRI MCP and total PIP bone oedema (p = 0.013 and p = 0.019 respectively).  Only five SLE patients fulfilled the criteria for ‘rhupus’ in that they had a positive ACPA or RF in the presence of erosive disease.

There was good correlation of MRI synovitis scores at the MCP joints with MCP ultrasound GS and PD (p = 0.003 and p < 0.001 respectively). There was excellent correlation of MRI and US wrist extensor tenosynovitis scores (p < 0.003)

Conclusion:

This is the largest study to date using MRI in lupus arthritis and the first study to combine US and MRI in the assessment of SLE patients. We have shown that erosive lupus arthritis is independent of RF or ACPA status, challenging the use of the term ‘Rhupus’ as the only manifestation of erosive arthritis in SLE. The negative association of bone oedema with anti-RA33 titres would suggest that those patients who have high titres are less likely to have more aggressive arthritis.  This association with a more favourable outcome has been reported before in RA but has not yet been studied in relation to lupus arthritis.

 

Patient No.	ACPA	RF	Anti-RA33 (titre)	Total MCP erosion score on MRI (range 0-50)	Total Wrist erosion score on MRI (range 0- 100 )	Total Extensor Tenosynovitis score on Ultrasound (range 0- 18 )	Total MCP Bone Oedema (range 0-12)
89	+	–	– (10.2)	24	7	3	0
45	+	–	– (8.4)	0	1	3	0
59	+	–	– (9.5)	22	10	2	6
2	–	+	– (6.8)	n/a	n/a	0	0
3	–	+	– (3.2)	33	7	0	19
6	–	–	+ (28)	0	1	0	0
16	–	–	+ (52)	2	5	0	0
33	–	–	+ (82)	3	1	0	0
37	–	–	+(316)	2	8	0	0
39	–	–	+ (96.2)	0	4	0	0
41	–	–	+ (83.7)	n/a	n/a	0	n/a
42	–	–	+ (78.5)	n/a	n/a	0	n/a
67	–	–	+ (40)	14	12	3	0

‘+’, positive antibody test, ‘-‘ negative antibody test, n/a, non-applicable as patient did not have an MRI scan

 

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/defining-hand-arthritis-in-systemic-lupus-erythematosus-from-an-ultrasound-magnetic-resonance-imaging-and-antibody-status-perspective/