Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose
Rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA) have vastly improved the diagnosis of rheumatoid arthritis (RA), but the diagnosis and management of seronegative RA patients remains a challenge. Musculoskeletal ultrasound (US) can improve the diagnosis of synovitis, and also reveal crystalline deposition potentially contributing to arthritis in a subset of patients.
Methods
We retrospectively reviewed clinical and US characteristics of 26 consecutive seronegative RA patients found to have crystalline deposits by US performed by 1 US-trained rheumatologist over 1 year. Images from 7 age-matched disease controls (4 osteoarthritis (OA), 2 seropositive RA, and 1 seronegative RA) were also reviewed. All images were reviewed by a 2nd rheumatologist.
Results
Typical of RA cohorts, the 26 patients were predominantly female (62%), with a median age of 57. RF and ACPA were by definition negative. Median levels of inflammatory markers were in normal ranges. 62% of the patients met 2010 ACR/EULAR classification criteria for RA. Median symptom duration was 1.4 years, and only 5 patients were receiving disease-modifying antirheumatic drugs (DMARDs) at the time of US. Metacarpophalangeal (MCP) joints were most commonly symptomatic (65%). By X-ray, only 2 patients had chondrocalcinosis, and 1 had erosion.
There was 100% inter-reader agreement of the US images, encompassing 7 anatomic sites (shoulder, elbow, wrist, hand, knee, ankle, and foot). Images in all 26 patients revealed multiple hyperechoic densities consistent with the US appearance of calcium pyrophosphate dihydrate (CPPD) vs. calcium hydroxyapatite crystals, and were not typical of gout. Calcific deposits, in all cases associated with synovitis, were identified in joints, tendons, and/or tendon sheaths. By comparison, control imaging demonstrated few scattered calcifications without synovitis in only 1 OA patient.
Nearly all 26 patients (90%) had calcifications in both joints and tendons. Calcification pattern in joints was most commonly round (79%), followed by punctate (45%), whereas calcification pattern in tendons was more frequently punctate (79%) followed by linear (42%). Over half (58%) of patients had all 3 patterns. Nine (35%) patients had US evidence of bony erosions. There were no effusions amenable to aspiration. Subsequent testing of 10 patients revealed elevated parathyroid hormone levels in 4 patients, a risk factor for CPPD.
Conclusion
Our findings of hyperechoic deposits associated with synovitis on US suggests that crystalline disease, such as CPPD arthropathy, may be an explanation for arthritis in a subset of seronegative RA patients. Although microscopic analysis is the gold standard in diagnosis of crystalline arthropathy, US may be valuable, particularly when X-rays are unrevealing and effusions amenable to aspiration are lacking. Detection of crystals may reveal abnormalities such as hyperparathyroidism, and may affect treatment strategies. Studies with synovial tissue or fluid crystal analysis prospectively evaluating the prevalence of crystal deposition are needed to evaluate the role for US in the screening of seronegative RA patients.
Disclosure:
S. L. Arvikar,
Arthritis Foundation,
2;
J. Lin,
None;
M. J. Kohler,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/musculoskeletal-ultrasound-reveals-calcific-deposition-arthropathy-in-seronegative-inflammatory-arthritis-patients/