Tuberculous arthritis of the ankle joint masquerading as rheumatoid arthritis in a patient with lupus nephritis

Neglected tropical rheumatic diseases

The complexities of dealing with rheumatic diseases in tropical countries are diverse and likely due to limited health care infrastructure, lack of diagnostic and therapeutic facilities, impact of dominant prevailing diseases, and the challenges of differentiating from infectious and non-infectious disease mimics. Several tropical diseases present with musculoskeletal and rheumatic manifestations and often pose a diagnostic dilemma to rheumatologists. The diagnosis is often delayed or the disease is misdiagnosed, leading to poor patient outcomes. Endemic tropical diseases like tuberculosis and leprosy have myriad rheumatic presentations and remain important differentials to consider in patients with rheumatic manifestations. Infection with human immunodeficiency virus is a great masquerade and can mimic manifestations of multiple diseases. The role of viral infections in triggering and perpetuating autoimmunity is well known and chikungunya arthritis is a classic example of the same. This review highlights the rheumatic manifestations of tropical diseases and aims to create awareness among the caregivers. Key Points • It is crucial to be aware and identify infectious diseases presenting with rheumatic manifestations in the tropics. • Presentations akin to classic rheumatic syndromes such as rheumatoid arthritis, spondyloarthritis, systemic lupus erythematosus and vasculitis are common.

Role of shear wave elastography of synovium to differentiate rheumatoid and tubercular arthritis

Background:

Synovitis is the underlying pathology in various arthritis, and sometimes, it is difficult to differentiate various arthritis clinically or even by imaging. The purpose of our study was to use shear wave elastography (SWE) to evaluate rheumatoid arthritis (RA) and tubercular (TB) arthritis and to differentiate them using synovial stiffness.

Methods:

The prospective study was performed on Supersonic Imagine Aixplorer Ultrasound (USG) machine using a linear array probe SL10-2 (2–10 MHz). A total of 29 participants, 15 of RA (ACR/EULAR criteria) and 14 of proven TB arthritis were included. Region of interest of 1 mm was applied on the hypertrophied synovium and quantitative SWE data in form of elasticity (kPa) and velocity (m/s) were measured. Discrete categorical data were presented as n (%). Mean values were recorded along with standard deviation and the range of values. To find a maximal cutoff value of elasticity and velocity - receiver operating characteristic curve were plotted.

Results:

The mean elasticity and velocity values were 54.81 ± 10.6 kPa and 4.2 m/s ± 0.42 for RA and 37 ± 10 kPa and 3.4 ± 0.47 m/s for TB group. Significant difference (P < 0.001) was seen in elastic modulus values between rheumatoid and TB group with cutoff of 43.6 kPa to differentiate the two groups (sensitivity – 86.7% and specificity – 80%). Similar significant (P < 0.001) results were seen with velocity values, with cutoff of 3.76 m/s (sensitivity – 86.7% and specificity – 80%).

Conclusion:

SWE shows the potential to be a useful adjunct to gray scale and color Doppler USG in differentiating various arthritis on the basis of elastic properties of the synovium. Elastic modulus and velocity are useful SWE quantitative parameters for synovial evaluation and can differentiate RA and TB arthritis.