Patients with incidental atlanto-axial pannus on cervical spine magnetic resonance imaging (MRI) who do not have a rheumatoid arthritis (RA) diagnosis are unlikely to have previously-unrecognized RA, according to results published in the Journal of Rheumatology.

The results indicated that for patients without RA, degenerative disease and tissue calcification may explain incidental atlanto-axial pannus on cervical spine MRI.

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The researchers searched the text of the Partners HealthCare Research Patient Data Registry for “atlanto-axial” and “pannus” in cervical spine MRI reports from 2001 to 2015. They reviewed cases with MRI reports describing pannus. In cases with confirmed atlanto-axial pannus, they used chart review to extract clinical data.


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Of 105 cases, 27.6% (n=29) had RA. Of these, only 1 participant did not already have an RA diagnosis at the time of the MRI scan.

Among participants without a history of RA, 1.3% (n=1) were diagnosed with RA. Participants without RA were significantly older (median age 79 vs 63 years, P <.0001), less frequently women (55% vs 86%, P =.0032), and more likely to have undergone prior cervical spine surgery (18% vs 0%, P =.016) compared with those who had RA.

Among participants without RA, 44.7% (n=34) had either a clinical diagnosis of calcium pyrophosphate dihydrate disease or imaging evidence of tissue calcification.

“Although the term pannus is commonly associated with RA, the imaging finding of atlanto-axial pannus is clearly not pathognomonic for RA,” the researchers wrote. “More specific terminology and radiographic definitions of soft tissue masses about the atlanto-axial joint are desirable.”

Reference

Joyce AA, Williams J, Shi J, Mandell JC, Isaac Z, Ermann J. Atlanto-axial pannus in patients with and without rheumatoid arthritis [published online April 1, 2019]. J Rheumatol. doi:10.3899/jrheum.181429