Extrinsic Allergic Alveolitis, also known as Hypersensitivity Pneumonitis, is a rare lung condition caused by an immune reaction to inhaled irritants such as fungal spores, bird feathers, and chemical vapors. Symptoms include cough, fever, and shortness of breath and can become chronic if left untreated. Other synonyms for this condition include extrinsic allergic alveolitis (EAA), hypersensitivity pneumonitis, allergic alveolitis, and farmer's lung. Treatment may include avoiding the allergen, using corticosteroids to reduce inflammation, and in severe cases, oxygen therapy or lung transplantation. Early detection and management are crucial to preventing long-term lung damage.