Antitubercular Therapy-associated Eosinophilic Granulomatosis with Polyangiitis Presenting as Acute Eosinophilic Pneumonia: A Rare Case Report

Introduction: Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare systemic vasculitis associated with asthma and eosinophilia.Drug-induced triggers are uncommon but clinically important.We report a case of EGPA potentially triggered by antitubercular therapy (ATT), presenting as acute eosinophilic pneumonia (AEP).Case presentation: A 38-year-old man with a history of asthma presented with progressive dyspnea, rash, and arthralgia shortly after starting ATT.Initial evaluation included a detailed clinical examination and laboratory investigations, which revealed marked eosinophilia and perinuclearantineutrophil cytoplasmic antibody (p-ANCA) positivity.High-resolution computed tomography (HRCT) of the chest revealed findings consistent with AEP.A skin biopsy was obtained from the rash, which demonstrated leukocytoclastic vasculitis.Diagnosis of EGPA was established based on the 2022 European Alliance of Associations for Rheumatology (EULAR)/ American College of Rheumatology (ACR) classification criteria.The Naranjo Adverse Drug Reaction Probability Scale was applied to assess the likelihood of ATT as the potential trigger.Results: Naranjo Adverse Drug Reaction Probability Scale classified the event as "probable." Key points supporting causality included temporal association with drug initiation, absence of alternative causes, objective evidence of vasculitis, discontinuation of ATT, and initiation of corticosteroids with plasma exchange (PLEX), which resulted in rapid clinical and radiological improvement.Conclusion: This case illustrates a probable instance of ATT-associated EGPA presenting as AEP.Clinicians should maintain a high index of suspicion for drug-induced vasculitis in patients with asthma and eosinophilic lung disease following ATT, as early recognition and timely management with drug withdrawal and immunosuppressive therapy can lead to favorable outcomes.