What is the diagnosis and management for a patient with a 1-month history of cough, colds, nocturnal chills, 3kg unintentional weight loss, reduced bowel movements, and reduced breath sounds in the upper lung fields, with a chest X-ray showing pulmonary fibrosis in the right upper and mid lung zone?

Diagnosis: Pulmonary Tuberculosis

This patient should be presumptively diagnosed with pulmonary tuberculosis and started immediately on standard four-drug anti-TB therapy (isoniazid, rifampin, pyrazinamide, and ethambutol) while awaiting microbiological confirmation. 1, 2

Clinical Reasoning

The constellation of findings strongly suggests active pulmonary TB:

• Classic symptom triad present: 1-month history of cough, nocturnal chills (night sweats equivalent), and 3kg unintentional weight loss are hallmark TB symptoms 1
• Upper lobe predominance on imaging: Chest X-ray showing pulmonary fibrosis in the right upper and mid lung zones is characteristic of postprimary (reactivation) TB, which predominantly affects apical and posterior segments of upper lobes in 91% of cases 3
• Reduced breath sounds in upper lung fields: Physical examination finding consistent with upper lobe parenchymal disease 4
• Duration of symptoms: Persistent cough >2-3 weeks warrants TB evaluation, particularly with constitutional symptoms 1, 5

Immediate Diagnostic Workup

Before or concurrent with treatment initiation, obtain:

• Three sputum samples for acid-fast bacilli (AFB) smear and mycobacterial culture - this is the diagnostic gold standard, though only 45% of culture-positive TB cases have positive smears 6, 7
• High-resolution CT chest - to better characterize the extent of disease, identify cavitation (present in 45% of postprimary TB), and assess for complications 8, 3
• Baseline laboratory tests: Complete blood count, hepatic enzymes, bilirubin, serum creatinine before starting anti-TB medications 2, 9
• HIV testing - TB and HIV co-infection significantly alters presentation and management 1

Note that normal chest radiograph does not exclude TB - culture-positive pulmonary TB with normal CXR occurs in up to 10% of cases, though this patient has abnormal imaging 7

Treatment Protocol

Standard Four-Drug Regimen (Intensive Phase: 2 months)

Start immediately without waiting for culture results given high clinical suspicion 2, 6:

• Isoniazid 5 mg/kg (max 300 mg) daily
• Rifampin 10 mg/kg (max 600 mg) daily
• Pyrazinamide 15-30 mg/kg daily
• Ethambutol 15-25 mg/kg daily

2, 9

Key Management Points

• Take medications 1 hour before or 2 hours after meals with full glass of water 9
• Monthly clinical monitoring is mandatory - specifically assess for hepatotoxicity symptoms (nausea, vomiting, abdominal pain, jaundice, dark urine) 2, 9
• Avoid alcohol and hepatotoxic medications/herbals during treatment 9
• Warn patient about orange discoloration of urine, sweat, tears, and potential permanent staining of contact lenses 9

Validation of Presumptive Diagnosis

Reassess at 3 months to confirm diagnosis 6:

• Clinical improvement: Resolution of cough, weight gain, improved energy
• Radiographic improvement: Expected in 70% of culture-positive TB cases by 3 months 6
• Culture results: Definitive confirmation if positive

Presumptive therapy is justified because it stops disease progression early and decreases transmission risk, benefits that outweigh the 8.3% risk of adverse reactions in patients ultimately found to have inactive disease 6

Critical Pitfalls to Avoid

• Do not delay treatment waiting for culture results - cultures take 6-8 weeks and disease progression/transmission continues 1, 6
• Do not use single-drug therapy - this is inadequate and promotes drug resistance 2
• Do not assume "fibrosis" on chest X-ray means inactive disease - this is a common cause of missed TB diagnosis; active disease can coexist with fibrotic changes 3
• Do not discontinue therapy if patient feels better early - emphasize completing full course to prevent resistance 9

Alternative Diagnoses to Consider

While TB is most likely, if cultures remain negative and no improvement occurs at 3 months, consider:

• Idiopathic pulmonary fibrosis (IPF) - though upper lobe predominance is inconsistent with typical IPF (which is basal) 5
• Hypersensitivity pneumonitis - requires detailed occupational/environmental exposure history 5
• Sarcoidosis - though typically presents with hilar lymphadenopathy 5

However, the acute presentation with constitutional symptoms, weight loss, and upper lobe distribution makes TB far more likely than these chronic interstitial lung diseases 5