|Year : 2017 | Volume
| Issue : 3 | Page : 130-131
Tuberculosis in rheumatology practice: The many faces of an old foe
Benzeeta Pinto, Aman Sharma
Department of Internal Medicine, PGIMER, Chandigarh, India
|Date of Web Publication||10-Aug-2017|
Department of Internal Medicine, PGIMER, Chandigarh - 160 012
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Pinto B, Sharma A. Tuberculosis in rheumatology practice: The many faces of an old foe. Indian J Rheumatol 2017;12:130-1
Tuberculosis (TB) is an ancient scourge that continues to kill millions of people every year. Despite the availability of effective treatment for over half a century, we are far from its eradication. HIV epidemic has caused resurgence of TB, and this old enemy has developed new weapons such as multidrug resistance. Hence, no practicing Indian physician can escape from having an in-depth knowledge of TB.
TB is equally relevant in rheumatology practice. The use of immunosuppression and biologicals, especially anti-tumor necrosis factors, puts our patients at risk of opportunistic infections. TB in this subset may have atypical presentations, and a high index of suspicion is required for making the diagnosis. Osteoarticular TB may also present to the rheumatologist as is reported in this issue by Prasad et al. Reactive manifestations of TB such as Poncet's disease and erythema nodosum may closely mimic rheumatic diseases.
Musculoskeletal TB is probably as old as the disease itself with Egyptian mummies showing evidence of vertebral TB. Osteoarticular TB accounts for 1%–5% of total TB cases with spinal TB being the most common accounting for nearly half of the cases. Pott's spine usually affects the thoracic vertebrae and presents with back ache with “red flag signs.” These include constitutional symptoms, night pains, and pain worsening on coughing and sneezing. However, TB of the spine may closely mimic seronegative spondyloarthropathy. TB of joints usually presents as a chronic monoarticular involvement of large joints such as hip and knee. Oligoarticular and polyarticular involvement is also well described, and this subset may mimic inflammatory arthritis., In the series reported by Prasad et al., knee is the most common joint involved with TB of the hip being much less common. An older series from India showed almost equal affection of hip and knee. Tubercular osteomyelitis is less common than articular involvement. In children, it may affect the phalanges and present with dactylitis leading to confusion with inflammatory arthritis. Multifocal tubercular osteomyelitis may occur in children and immunocompromised patients. TB may also involve soft tissues, leading to tenosynovitis, bursitis, and myositis. This may be due to contiguous spread from underlying bone or hematogenous dissemination. These uncommon presentations may be easily mistaken for soft tissue inflammatory conditions leading to a delay in diagnosis.
Currently the term Poncet's disease is restricted to reactive arthritis occurring in TB without bacteriological involvement of joints. Over 200 cases have now been described in literature with as many as 35% of the reported cases being from India. Poncet's disease may occur with both pulmonary and extrapulmonary TB; however, it is more common with extrapulmonary TB, particularly tubercular lymphadenitis. It can present as acute or chronic oligoarthritis or polyarthritis. It is nonerosive and nondeforming with complete response to ATT.
Diagnosis of osteoarticular TB requires a high index of suspicion. Constitutional symptoms may not be present in all patients. In the current series by Prasad et al less than one-third of the patients had constitutional symptoms. However, this may be due to a referral bias as patients with fever may be easily diagnosed as TB by general practitioners. Radiology may assist in the diagnosis, but definitive diagnosis requires histopathological and microbiological confirmation. Magnetic resonance imaging (MRI) is the investigation of choice for early detection. However, it may not always be possible to differentiate between TB and inflammatory arthritis on radiology. Gradually narrowing joint space and peripherally placed osseous erosions on X rays are suggestive of tubercular involvement. A study comparing MRI of joints in RA and tubercular involvement found that uniform synovial thickening, large size of bone erosion, rim enhancement at site of bone erosion, and extra-articular cystic masses were more frequent and more numerous in tuberculous arthritis. Nucleic acid amplification tests have shown promising results in extrapulmonary TB. In a recent study of eighty patients synovial fluid/pus multiplex polymerase chain reaction showed a sensitivity of 81.8% in clinically suspected cases and 100% in confirmed cases with a specificity of 100%. Another recent study from the same group showed that the use of multitargeted loop-mediated isothermal amplification assay for diagnosing osteoarticular TB using IS6110 and MPB64 resulted in diagnosing six additional cases out of 140 samples over and above those detected with the use of single target alone. GeneXpert and GenoType MTBDRplus assay have been shown to have a sensitivity of 82% and 72%, respectively, with a specificity of 100% in pus samples from osteoarticular TB.
The diagnosis of Poncet's disease rests on the demonstration of an active focus of TB elsewhere in the body and complete response to ATT without recurrence of arthritis or joint sequelae. Based on our experience of 23 cases, we have recently proposed a diagnostic criterion for the same.
The treatment of osteoarticular TB is similar to TB at other sites with short-course regimens being as effective as longer duration of treatment. Surgical intervention is limited to diagnosis and management of complications.
In conclusion, osteoarticular TB may present to the rheumatologist masquerading as inflammatory arthritis. The diagnosis is often delayed as it is not considered. Newer imaging modalities and molecular diagnostics coupled with a high index of suspicion will aid earlier diagnosis and treatment.
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