A 28-year-old woman from Delhi with a history of treated TB 2 years ago now presents with persistent cough for 2 months. Chest X-ray shows multiple thin-walled cavities in the bilateral upper lobes with minimal surrounding consolidation. High-resolution CT confirms cavitary lesions with an air-fluid level in the right upper lobe cavity. Sputum smear microscopy is negative. What is the most likely diagnosis?

Explanation

## Aspergilloma in Post-TB Cavity **Key Point:** An air-fluid level within a thin-walled cavity in a patient with prior TB history and negative sputum smear microscopy is highly suggestive of aspergilloma (fungal ball) rather than active TB. ### Pathophysiology of Aspergilloma Formation 1. **Predisposing factor**: Previous TB leaves behind fibrotic cavities with poor blood supply. 2. **Fungal colonization**: *Aspergillus fumigatus* (most common) colonizes these cavities, forming a fungal ball. 3. **Imaging characteristics**: The fungus grows within the cavity, creating a mobile mass that may show an air-fluid level on CT. ### Distinguishing Features: Aspergilloma vs. Active TB | Feature | Aspergilloma | Active TB | |---------|--------------|----------| | **Sputum smear** | Negative for AFB | Positive for AFB (if cavitary) | | **Cavity wall** | Thin-walled, well-defined | Thick-walled with surrounding consolidation | | **Air-fluid level** | Present (fungal ball + fluid) | Absent | | **Surrounding infiltrate** | Minimal or absent | Patchy consolidation around cavity | | **CT appearance** | Mobile mass within cavity | Homogeneous cavity with debris | | **Clinical presentation** | Hemoptysis, chronic cough | Fever, night sweats, constitutional symptoms | **High-Yield:** Aspergilloma is a common complication in 10–15% of patients with residual TB cavities. The presence of an air-fluid level is a red flag for fungal colonization. **Clinical Pearl:** Hemoptysis is the most common presenting symptom of aspergilloma due to erosion of cavity walls and invasion of blood vessels. This patient's persistent cough and negative sputum smear support this diagnosis. ### Diagnostic Clues in This Case - **Negative sputum smear**: Rules out active TB (especially with cavitary disease). - **Air-fluid level on CT**: Pathognomonic for aspergilloma; the fungal ball moves with gravity. - **Minimal surrounding consolidation**: Active TB would show patchy infiltrates around cavities. - **History of treated TB**: Pre-existing cavity provides the substrate for fungal colonization. **Mnemonic: ASPERGILLOMA** — **A**ir-fluid level, **S**putum smear **N**egative, **P**rior **T**B cavity, **E**rosion of vessel walls → hemoptysis, **R**esidual fibrotic cavity, **G**rowth of *Aspergillus*, **I**maging shows mobile mass, **L**ow-grade infection, **L**ung parenchyma spared. ### Management Implications - **Diagnosis**: Serology (IgG antibodies to *Aspergillus*), sputum culture for *Aspergillus*, CT imaging. - **Treatment**: Antifungal therapy (itraconazole, voriconazole) for symptomatic disease; surgical resection (cavity obliteration) for recurrent hemoptysis. [cite:Harrison 21e Ch 205; Robbins 10e Ch 8]