A Teenage Girl with Joint Swelling

Hnin Thuzar Aung, Soe San, Emoon Sandee

A twelve-years-old girl from Kyauk-tan Township, Yangon, was admitted to Parami General Hospital on 28^th February, 2025 with the chief complaint of right knee joint swelling on and off for one month, and current right knee joint swelling for three days. Apart from slight pain on movement, there were no other joint involvement. She could walk with a limp. There were no constitutional symptoms like fever, night sweats, loss of appetite and loss of weight. There were no associated respiratory, gastrointestinal or genitourinary symptoms.

A month ago, she suffered from right knee joint swelling for about five days. There was no cough, but associated with low grade fever for one day. There was no preceding injury apart from doing exercise at school. The knee joint swelling recovered spontaneously with analgesic and ice packing by self-prescription.

Regarding rheumatological history, there was no morning stiffness, Raynaud’s phenomenon, photosensitive skin rashes, other joint pain or swelling apart from right knee joint. There were no alopecia, oral ulcers, eye symptoms, nail changes. Neurologically, there was no weakness or sensory disturbance. There was no hematological history, pallor, bleeding manifestation. Past medical and surgical history, birth history, immunization history were not relevant. Regarding drug history, she had not been taking regular drugs like NSAID, anticoagulants. There was no history of tuberculosis contact, rheumatoid arthritis, systemic lupus erythematosus (SLE) or nodal osteoarthritis, or history of bleeding diathesis in the family. Regarding social history, she lives in a well-ventilated private house in Kyauk-tan.

On examination, she was well, alert, afebrile, body weight of 31.5 Kg (5^th centile). There was no pallor, jaundice, red eye, eye pain or dry eye. BCG scar was present. No skin lesion like malar rashes, discoid rashes, scaly rashes. No oral ulcers, No nail pitting, no onycholysis, no cyanosis. No petechiae, no palpable purpura or cervical lymph node enlargement.

On local examination, there were no remarkable signs apart from swelling of the right knee joint which was not tender, and there were no signs of inflammation in the overlying skin. Patellar tap was present. Range of movement was normal, with slightly diminished range of motion with minimal pain on flexion and extension. There was no joint deformity. All other joints were normal in appearance and in function.

Thus, the provisional diagnosis of recurrent monoarticular arthritis was made, which was probably due to (1) infection (might be septic arthritis or tuberculous arthritis), (2) JIA, (3) Traumatic, (4) Crystal deposition, (5) Reactive arthritis.

Blood tests, revealed that CRP, ESR, ASO were mildly elevated, ANA was trace (1/160, speckled), and vitamin D level was severely insufficient. Other blood tests such as complete blood picture, uric acid, rheumatic factor, serum calcium, magnesium, phosphate levels were normal. X ray both knees (AP, lateral) showed joint effusion  in right supra-patellar region, associated with soft tissue swelling and there was no underlying bony erosion. Ultrasound (right knee) showed synovial thickening with moderate joint effusion in suprapatellar region with soft tissue swelling, no obvious underlying bony erosion. Popliteal vessels are patent. No popliteal cyst and was suggestive of septic arthritis (right knee joint). Initial management was given to cover septic arthritis with rest, ice packing, painkillers, and antibiotics injection.

An orthosurgeon was consulted and he suggested that it was most likely due to tuberculous effusion, and less likely septic arthritis in the context of recurrent painless right knee joint swelling with no sign of inflammation in overlying skin and range of movement in flexion 0-130’ (near normal) and suggested to arthrotomy and joint debridement.

TB screening were done where tuberculin test was negative (4 mm), and TB feron FIA (IFN-gamma) test was also negative. Retroviral antibody and syphilis duo test were non-reactive. There was no active lung lesion and no hilar glands enlargement in chest X-ray.

Arthrotomy and joint debridement was done on (4.3.25). There was synovial hypertrophy, and large caeseation necrosis and tubercles popped out from joint from infrapatellar fat pad. Cartilage still intact and so not favorable for a diagnosis of septic arthritis.

On synovial fluid RE, appearance was slightly turbid yellow, Glucose 80 mg %, Protein 4424 mg/dl, RBCs were present; Total cell count ; 3000 cells/cumm with lymphocyte  count 75%. Synovial fluid Gram stain showed few pus, ZN stain showed no AFB and culture was sterile.

Histological diagnosis was compatible with tuberculous synovitis showing epithelioid granulomas replete with Langhan’s giant cells associated with areas of caseous necrosis, accompanied by infiltrates of plasma cells and lymphocytes with hemorrhages.

Fig 2. Histopathology of lesion

Definitive diagnosis was tuberculous synovitis and arthritis of right knee joint and was referred for definitive management anti-tuberculous therapy 2(HRZE)/10(HR) with follow-up one week later to monitor side effects of anti-TB and to assess wound condition.

Discussion

TB remains a major health problem worldwide and according to the WHO, approximately two billion people worldwide have latent TB infection.

Tuberculosis (TB) properly refers only to disease caused by Mycobacterium tuberculosis (for which humans are the main reservoir). Although the lungs are the initial site of infection, disease can spread to many organs. Tuberculosis outside the lung, also known as isolated tuberculosis, usually results from hematogenous dissemination, sometimes from lymphatic or contiguous spread of bacilli from a primary focus of infection, which is usually the lung, kidney or a lymph node.

Typically, there is a long latent period between primary tuberculosis and isolated tuberculosis. Only 30% of patients with isolated TB have radiographic evidence of current or previous pulmonary TB. In 50% of patients, the primary focus cannot be identified.¹²

Involvement of joints with the tubercle bacillus is an uncommon but treatable type of arthritis. Osteoarticular tuberculosis (OTB) affecting the spine and joints accounts for only 1–3% of all cases of tuberculosis and 10–11% of extra-pulmonary tuberculosis.¹² The most common presentation is chronic monoarthritis, which primarily involves the large weight-bearing joints, in particular the hips, knees, and ankles, and occasionally involves smaller non weight-bearing joints such as wrist, elbow, and small joints of hands. Oligo- or polyarthritis is not rare. It often has a chronic course.¹²

Despite the presence of Phemister’s triad (peri-articular osteoporosis, peripheral osseous erosions, and progressive gradual narrowing of the interosseous space), the diagnosis is often not made or considered until cartilage or bone destruction is present and joint function compromised. The delay in reaching for the diagnosis might be due in part to the lack of TB exposure history and the absence of a primary focus and partly due to the fact that it can mimic other for its varied clinical presentations. Thus a high index of clinical suspicion is required in making the diagnosis of OTB, especially in the context of persistent monoarthritis. Early diagnosis of OTB is essential to preserve articular cartilage and joint integrity.

Tuberculin skin test and radiological findings may suggest TB infection. Serum interferon gamma test is sensitive and specific for detection of latent TB infection.

Synovial fluid analysis plays a crucial role in diagnosing tuberculosis (TB) of the joints. Synovial fluid for routine examination in TB arthritis typically shows a high white blood cell count (over 10,000/mm3), often with a predominance of polymorphonuclear leukocytes. Synovial fluid glucose levels are usually low, and protein levels are elevated in TB arthritis. Synovial fluid with WCC of >50 000/mm3 and PMN level of >75% point towards acute septic arthritis, while WCC of 2000 to 100 000/mm3 and PMN level of >50% suggest inflammatory arthritis. In tuberculosis, the WCC is typically in the inflammatory range of 10 000 to 20 000/cu mm.⁴

Adenosine deaminase (ADA) activity in synovial fluid (SF-ADA) can be used as an additional tool for the diagnosis of tuberculosis joint infection in cases of negative SF culture and PCR. It may be considered as a cost-effective, less invasive and readily available diagnostic tool for TB arthritis especially in resource-limited settings. The most commonly used cut-off values for ADA were ≥40 IU/L for pleural and peritoneal tuberculosis, and ≥10 IU/L for meningeal tuberculosis. However, the cut-off point of adenosine deaminase activity for the diagnosis of OTB varied across the publications, being 40–50 IU/L the median value. Pooled sensitivity and specificity of ADA activity was 94% (95% confidence interval [CI], 0.89–98; I2 = 23%) and 88% (95% CI, 83–92; I2 = 83%), respectively.¹³

Acid fast bacilli can be identified on SF smear (20% sensitive), microbiological culture (80% sensitive) and TB-PCR is both sensitive and specific in detecting TB from tissues and synovial fluid (62.5% sensitive).¹² Histological confirmation remains the gold standard in diagnosis, showing chronic granulomatous inflammation with or without necrosis on synovial biopsy (80 – 96% sensitive).¹²

If diagnosed early, OTB can be managed conservatively by one year treatment of anti-TB Surgical intervention including debridement, synovectomy and arthroplasty might be needed with increasing joint damage, sometimes might be needing total knee replacement.

All in all, the diagnosis of TB arthritis is often delayed due to lack of awareness, insidiousness in onset, lack of characteristic early radiographic findings and often lack of constitutional or pulmonary involvement, requiring high index of suspicion, especially in the context of persistent monoarthritis in a susceptible host. Early diagnosis, specific and adequate treatment is essential to preserve the articular cartilage and joint integrity and most importantly quality of life.

References

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13. J.C. Cortes-Quiroz etal, (2024) Performance of adenosine deaminase in synovial fluid for the diagnosis of tuberculous arthritis: A systematic review and meta-analysis, Reumatología Clínica 20 117–122, accessed July 23th, 2025

Author Information

Hnin Thuzar Aung, Soe San, Emoon Sandee

1. Consultant Paediatrician, M.B.,B.S, M.Med.Sc(Paed), DCH, MRCPCH, FRCP(Edinburgh), Diploma in Allergy & Asthma, C.M.C,Vellore,India
2. Associate Professor, M.B.,B.S, M.Med.Sc (Orthopedics) , Dr. Med.Sc (Orthopedics), Fellowship in Paediatrics Orthopedics (Seoul), Travelling Fellowship in Paediatrics Orthopedics (POSNA) , Regional Fellowship in AO Trauma (Mumbai)
3. M.B.,B.S