A patient with lymph node tuberculosis who is in the continuation phase of isoniazid + rifampicin develops sterile migratory polyarthritis (Poncet’s disease); how should the arthritis be treated and should the anti‑tuberculosis regimen be changed?

Management of Poncet's Disease During TB Continuation Phase

Continue the current isoniazid and rifampicin regimen without modification and treat the arthritis symptomatically with NSAIDs or corticosteroids, as Poncet's disease is a sterile reactive arthritis that resolves with continuation of anti-tuberculosis therapy. 1

Understanding Poncet's Disease

Poncet's disease is a sterile, reactive polyarthritis that occurs during active tuberculosis infection and represents a distinct entity from tuberculous arthritis (which involves direct mycobacterial invasion of joints). 2, 3 This condition characteristically presents as:

• Sterile migratory polyarthritis without acid-fast bacilli in joint fluid 2
• Asymmetrical polyarthritis is the most common presentation pattern 1
• Can occur at any stage of active TB, including after initiation of anti-TB treatment 1
• Considered a reactive arthritis phenomenon, not direct joint infection 2, 3

Management of the Arthritis

The arthritis itself requires only symptomatic treatment:

• NSAIDs are first-line for pain and inflammation control 1
• Short-term corticosteroids may be used for severe symptoms 1
• Joint aspiration is not necessary unless septic arthritis needs to be excluded 2
• The arthritis typically resolves with symptomatic treatment and continuation of anti-TB drugs 1

Anti-Tuberculosis Regimen Management

Do not modify the current continuation phase regimen:

• Continue isoniazid and rifampicin as prescribed for lymph node tuberculosis 4, 5
• The standard continuation phase for extrapulmonary TB is 4 months of isoniazid and rifampicin (total 6 months treatment) 4
• Never add or change a single drug in the regimen, as this promotes drug resistance 4, 6
• The arthritis will resolve as the tuberculosis is treated; changing the TB regimen is not indicated 1

Critical Monitoring During Continuation Phase

Ensure appropriate follow-up for both conditions:

• Monitor TB treatment response with clinical assessment at least monthly 5, 7
• Document resolution of lymphadenopathy as marker of treatment efficacy 2
• Track arthritis symptoms to confirm improvement with symptomatic therapy 1
• Watch for hepatotoxicity from isoniazid and rifampicin, especially if NSAIDs are added 5, 7

Common Pitfalls to Avoid

Do not mistake Poncet's disease for treatment failure:

• Six out of seven patients in one series developed arthritis after starting anti-TB drugs, not before 1
• This paradoxical worsening does not indicate drug resistance or treatment failure 1
• The arthritis is not an indication to extend treatment duration beyond standard 6 months for lymph node TB 4

Do not confuse with tuberculous arthritis:

• Tuberculous arthritis typically presents as monoarthritis of weight-bearing joints (hip, knee) 3
• Tuberculous arthritis requires joint aspiration showing acid-fast bacilli and often needs 9 months of treatment 3
• Poncet's disease is polyarticular, migratory, and sterile 2, 1

Do not stop or modify anti-TB therapy:

• The arthritis resolves with continuation of the same anti-TB regimen 1
• Treatment interruptions in the continuation phase can lead to relapse or resistance 4, 6
• Complete the full 6-month course (2 months intensive phase + 4 months continuation phase) for lymph node TB 4, 5

Duration of Total Treatment

For lymph node tuberculosis:

• Standard treatment is 6 months total (2 months of isoniazid, rifampicin, pyrazinamide, ethambutol followed by 4 months of isoniazid and rifampicin) 4
• The presence of Poncet's disease does not require extension of treatment duration 1
• Extension to 9 months is only indicated for cavitary pulmonary TB with positive cultures at 2 months, not for extrapulmonary TB 4