What is the recommended treatment regimen and monitoring plan for scrofuloderma in a patient without known drug‑resistant tuberculosis?

Scrofuloderma Management

Treat scrofuloderma with the standard 6-month tuberculosis regimen: 2 months of daily isoniazid, rifampin, pyrazinamide, and ethambutol (2HRZE) followed by 4 months of daily isoniazid and rifampin (4HR), administered under directly observed therapy. 1

Initial Treatment Regimen (Intensive Phase: 2 Months)

• Administer four drugs daily for 56 doses over 8 weeks: isoniazid 5 mg/kg (≈300 mg), rifampin 10 mg/kg (≈600 mg for patients ≥50 kg, 450 mg for <50 kg), pyrazinamide 35 mg/kg daily (maximum 2.0 g for patients >50 kg), and ethambutol 15 mg/kg daily. 1

• The four-drug approach is mandatory because primary isoniazid resistance exists in many communities; ethambutol should only be omitted if drug susceptibility testing confirms full susceptibility to both isoniazid and rifampin AND community isoniazid resistance is documented <4%. 1

• Add pyridoxine (vitamin B6) 25-50 mg daily to prevent peripheral neuropathy in all patients at risk, including pregnant women, HIV-infected patients, those with diabetes, alcoholism, malnutrition, or chronic renal failure. 1

Continuation Phase (Months 3-6)

• Administer two drugs daily for 126 doses over 18 weeks: isoniazid 5 mg/kg (≈300 mg) and rifampin 10 mg/kg (≈600 mg). 1

• This standard 6-month regimen applies to scrofuloderma as it is a form of extrapulmonary tuberculosis that should be managed according to the same principles as pulmonary tuberculosis. 2

Treatment Duration Extension Criteria

• Extend continuation phase to 7 months (total 9 months) only if the patient has cavitary pulmonary disease on initial chest radiograph AND remains culture-positive after completing the 2-month intensive phase. 1

• For scrofuloderma specifically, a 9-month daily regimen of rifampin and isoniazid has demonstrated 92% resolution within the first 6 months with no relapses during 3-year follow-up, though the standard 6-month regimen remains preferred per current guidelines. 3

Directly Observed Therapy (DOT)

• Implement DOT for all tuberculosis patients to ensure treatment completion and prevent emergence of drug resistance. 1

• A 5-days-per-week DOT schedule is an acceptable alternative to 7-days-per-week based on extensive clinical experience. 1

Monitoring Plan

• Obtain baseline drug susceptibility testing for isoniazid, rifampin, ethambutol, and pyrazinamide before or immediately after treatment initiation. 1

• Perform baseline hepatic function tests (AST/ALT and bilirubin) in high-risk patients including HIV-infected individuals, pregnant women, those with chronic liver disease history, and regular alcohol users. 1

• Monitor clinical response by assessing reduction in lymph node size, drainage, and healing of skin lesions at monthly intervals. 4

• For scrofuloderma patients, clinical response (weight gain, inflammatory markers, repeat imaging of affected lymph nodes) is the primary monitoring tool since sputum production is typically absent in extrapulmonary tuberculosis. 4

Management of Drug-Resistant Scrofuloderma

• If rifampin resistance is detected (as can occur with treatment non-adherence), immediately consult a tuberculosis specialist and initiate an MDR-TB regimen with at least five effective drugs. 4, 5

• Never add a single drug to a failing regimen—this fundamental principle prevents acquired resistance to the new drug; instead add at least two, preferably three, new drugs simultaneously. 4

• For confirmed MDR/RR-TB scrofuloderma without fluoroquinolone or bedaquiline resistance, the 6-month BPaLM regimen (bedaquiline, pretomanid, linezolid, moxifloxacin) is preferred over longer 18-20 month regimens. 6

• If BPaLM is unavailable or contraindicated, construct longer regimens using WHO Group A drugs (moxifloxacin, bedaquiline, linezolid) plus at least one Group B drug (clofazimine, cycloserine/terizidone). 4, 6

Critical Pitfalls to Avoid

• Do not use twice-weekly or thrice-weekly intermittent dosing in HIV-infected patients or those with high-burden disease, as missed doses effectively become once-weekly therapy leading to treatment failure and acquired resistance. 1

• Do not use injectable agents (kanamycin, capreomycin, streptomycin) in MDR-TB regimens, as current guidelines recommend against these due to nephrotoxicity and ototoxicity concerns. 4, 6

• Do not assume treatment failure after only 2-3 months of therapy; scrofuloderma may require the full 6-month course for complete resolution, with 92% of patients showing resolution within this timeframe. 3

• Ensure compliance monitoring is rigorous, as the case report of bilateral scrofuloderma with rifampin resistance highlights how poor adherence leads to drug resistance emergence. 5