A 45-year-old woman from Delhi with a history of pulmonary tuberculosis treated 8 years ago presents with hemoptysis and dyspnea. High-resolution CT chest shows a cavitary lesion in the right upper lobe with a mobile intracavitary mass. Sputum smear microscopy is negative for acid-fast bacilli. Histopathology of the intracavitary mass shows fungal hyphae with acute angle branching. What is the most likely diagnosis?

Explanation

## Aspergilloma: Pathology and Clinical Context ### Definition and Pathogenesis **Key Point:** Aspergilloma (fungal ball) is a non-invasive colonization of a pre-existing cavity by *Aspergillus fumigatus*, most commonly occurring in old tuberculous cavities. ### Epidemiology and Risk Factors - **Most common cause of cavitary disease:** Old tuberculosis (>80% of cases) - **Other predisposing cavities:** Sarcoidosis, histoplasmosis, cystic fibrosis, emphysematous bullae - **Geographic distribution:** More common in areas with high TB prevalence (India, Southeast Asia) - **Timing:** Develops months to years after TB cure; patient's 8-year history fits perfectly ### Pathological Features | Feature | Aspergilloma | Invasive Aspergillosis | |---------|-------------|----------------------| | **Tissue invasion** | None (non-invasive) | Angioinvasive | | **Immune status** | Normal or mildly immunocompromised | Severely immunocompromised | | **Histology** | Fungal ball with inflammatory response | Hyphal invasion of tissue | | **Branching angle** | Acute (45°) | Acute (45°) | | **Sputum AFB** | Negative | Negative | | **Culture** | *Aspergillus fumigatus* | *Aspergillus* species | ### Microscopic Identification **High-Yield:** *Aspergillus fumigatus* shows: - **Acute angle branching (45°)** — distinguishes from *Mucor* (90° branching) - **Septate hyphae** — unlike *Mucor* (non-septate) - **Conidiophores with phialides** — characteristic fruiting structures **Mnemonic:** **AFAR** — *Aspergillus* = **A**cute angle, **F**umigatus, **A**cute branching, **R**ight upper lobe (classic location) ### Clinical Presentation 1. **Hemoptysis** — most common symptom (75–90% of cases) - Caused by erosion of fungal ball into blood vessels - Can be life-threatening 2. **Dyspnea** — from airway obstruction 3. **Cough** — productive or dry 4. **Constitutional symptoms** — typically absent (unlike active TB) ### Radiological Features ```mermaid flowchart TD A[Old TB Cavity]:::outcome --> B[Aspergillus colonization]:::outcome B --> C{Imaging findings}:::decision C -->|Chest X-ray| D["Cavitary lesion with<br/>mobile intracavitary mass<br/>Halo sign on CT"]:::outcome C -->|CT chest| E["Air crescent sign<br/>Mobile fungal ball<br/>Surrounding inflammation"]:::outcome D --> F[Hemoptysis risk]:::urgent E --> F ``` **Key Point:** The **air crescent sign** (crescent of air around the fungal ball) is pathognomonic for aspergilloma on CT imaging. ### Why Sputum AFB is Negative **Clinical Pearl:** Aspergilloma is a complication of *cured* TB, not active TB. The patient's negative sputum smear reflects: - Absence of viable mycobacteria - Successful prior anti-TB therapy - Fungal colonization of a residual cavity ### Diagnostic Confirmation 1. **Histopathology:** Acute-angle branching septate hyphae (as in this case) 2. **Culture:** *Aspergillus fumigatus* (gold standard) 3. **Serology:** Precipitating antibodies to *Aspergillus* (high sensitivity in aspergilloma) 4. **Imaging:** Air crescent sign on HRCT ### Management Principles **High-Yield:** Treatment depends on symptoms: - **Asymptomatic:** Observation (many remain stable) - **Hemoptysis:** Antifungal therapy (itraconazole, voriconazole) ± bronchial artery embolization - **Severe/refractory:** Surgical resection of cavity and fungal ball [cite:Robbins 10e Ch 8]