A 6-year-old boy from Delhi presents with a 2-week history of fever, cough, and progressive respiratory distress. His father was treated for pulmonary TB 4 months ago. On examination, the child is febrile (38.5°C), tachypneic, and has bilateral crackles on auscultation. Chest X-ray shows innumerable 1–2 mm nodules diffusely distributed throughout both lung fields, creating a 'millet seed' appearance. Mantoux test shows 15 mm induration. The child is otherwise immunocompetent. What is the most likely diagnosis and the immediate management priority?

Explanation

## Diagnosis and Management: Miliary Tuberculosis ### Clinical Presentation of Miliary TB **Key Point:** Miliary TB is a severe form of disseminated tuberculosis characterized by hematogenous spread of M. tuberculosis throughout the lungs and other organs. It is a medical emergency in children. ### Diagnostic Features in This Case **High-Yield:** The classic triad for miliary TB diagnosis: 1. **Radiological finding:** Innumerable 1–2 mm nodules in a "millet seed" pattern (miliary = resembling millet seeds) distributed bilaterally and symmetrically 2. **Clinical context:** Recent TB contact (father treated 4 months ago) + immunocompetent child 3. **Positive tuberculin test:** Confirms TB infection | Feature | Miliary TB | Acute Pneumonia | Pulmonary Edema | |---------|-----------|-----------------|------------------| | **Onset** | Gradual (weeks) | Acute (days) | Acute to subacute | | **CXR pattern** | Diffuse 1–2 mm nodules | Lobar/segmental consolidation | Bilateral perihilar opacities, Kerley B lines | | **Contact history** | TB contact common | Not specific | Cardiac history | | **TST** | Positive | Negative | Negative | | **Fever pattern** | Low-grade, persistent | High-grade | Variable | ### Pathogenesis of Miliary TB in Children **Mnemonic: DISSEMINATE** - **D**irect erosion of caseous focus into a blood vessel - **I**mmune system overwhelmed by high bacillary load - **S**pread via lymphohematogenous route - **S**eeding of lungs, liver, spleen, CNS, bones - **E**arly in primary TB (often within 6 months of infection) - **M**ore common in young children (<5 years) and immunocompromised hosts - **I**mmunity inadequate to contain infection - **N**odules appear as "millet seeds" on CXR - **A**cute respiratory distress and systemic toxicity - **T**reatment must be initiated urgently - **E**xtra-pulmonary involvement common (TB meningitis in 10–30%) ### Immediate Management Priority **Clinical Pearl:** Miliary TB is a medical emergency. The immediate management priority is: 1. **Initiate anti-TB therapy immediately** (do not wait for culture confirmation) - Standard 4-drug regimen: HRZE (Isoniazid, Rifampicin, Pyrazinamide, Ethambutol) for 2 months, then HR for 7 months (total 9 months for miliary TB) 2. **Supportive care:** Oxygen therapy, nutritional support, management of complications 3. **Investigate for TB meningitis:** Lumbar puncture with CSF analysis (cell count, protein, glucose, ADA, culture) 4. **Monitor for complications:** Hepatotoxicity, peripheral neuropathy, immune reconstitution inflammatory syndrome (IRIS) **Key Point:** Do NOT delay anti-TB therapy while awaiting culture or drug susceptibility results. Sputum smear microscopy is often negative in miliary TB due to the distribution of bacilli in the lungs. ### Why Miliary TB Is a Pediatric Emergency - High mortality if untreated (>90%) - Risk of TB meningitis (CNS involvement) - Respiratory failure from massive pulmonary infiltration - Rapid progression in young children with immature immunity [cite:Park 26e Ch 9; Ghai Essential Pediatrics 10e Ch 13]