Human brucellosis mimicking axial spondyloarthritis: a challenge for rheumatologists when applying the 2009 ASAS criteria

Axial Spondyloarthritis: Mimics and Pitfalls of Imaging Assessment

Axial spondyloarthritis (axSpA) is a chronic inflammatory disorder that predominantly involves the axial skeleton. Imaging findings of axSpA can be divided into active changes, which include bone marrow edema, synovitis, enthesitis, capsulitis, and intra-articular effusion, and structural changes, which include erosions, sclerosis, bone fatty infiltration, fat deposition in an erosion cavity, and bone bridging or ankylosis. The ability to distinguish between imaging lesions suggestive of axSpA and artifacts or lesions suggestive of other disorders is critical for the accurate diagnosis of axSpA. Diagnosis may be challenging, particularly in early-stage disease and magnetic resonance imaging (MRI) plays a key role in the detection of subtle or inflammatory changes. MRI also allows the detection of structural changes in the subchondral bone marrow that are not visible on conventional radiography and is of prognostic and monitoring value. However, bone structural changes are more accurately depicted using computed tomography. Conventional radiography, on the other hand, has limitations, but it is easily accessible and may provide insight on gross changes as well as rule out other pathological features of the axial skeleton. This review outlines the imaging evaluation of axSpA with a focus on imaging mimics and potential pitfalls when assessing the axial skeleton.

When brucellosis met the Assessment of SpondyloArthritis international Society classification criteria for spondyloarthritis: a comparative study

OBJECTIVES

To distinguish brucellosis patients fulfilling the Assessment of SpondyloArthritis international Society (ASAS) classification criteria for spondyloarthritis (SpA) from SpA patients.

METHODS

Brucellosis patients diagnosed from September 2012 to December 2017 who met the ASAS classification criteria for SpA were analyzed with clinical characteristics and laboratory and imaging examinations. Axial or peripheral SpA patients were respectively included into the comparative analysis with a 4:1 ratio.

RESULTS

Twenty-two brucellosis (10 axial and 12 peripheral) patients (male, 16 cases; 72.72%; mean (S.D.) age, 40.23 (16.49) years) and 88 SpA patients were included. All brucellosis patients had been misdiagnosed or considered as SpA before admission to our center. The brucellosis patients had shorter disease duration (axial, P = 0.001; peripheral, P = 0.108). More than half (59.09%) of the patients had contact history with livestock. The low back pain (LBP) of brucellosis patients was generally less improved with exercise (axial, P = 0.001; peripheral, P = 0.008). More brucellosis patients had myalgia (axial, P < 0.001; peripheral, P = 0.071) or fever (axial, P < 0.001; peripheral, P = 0.107). None of them had positive HLA-B27. Blood culture tests were performed in all brucellosis patients and only 4 (18.18%) were positive. Twenty (90.91%) brucellosis patients were gold-immunochromatographic assay (GICA) positive. Bone marrow edema and bone erosion in sacroiliac joints were respectively detected in 100% (10/10) and 90% (9/10) axial brucellosis patients by MRI. Adjacent muscle involvement was found in 80% (8/10) of the patients.

CONCLUSIONS

Indicators including disease duration, contact history of livestock, features of LBP, myalgia, fever, and HLA-B27 can help the differential diagnosis of brucellosis and SpA. GICA test and sacroiliac joints MRI can furtherly confirm the diagnosis of brucellosis.