RESUMO
Good's syndrome is a rare, acquired immunodeficiency condition characterized by thymoma and hypogammaglobulinemia, which increases the risk of recurrent infections. Immunoglobulin replacement therapy (IgRT) is the key treatment for recurrent infections. We describe the case of a 57-year-old male with a history of an anterior mediastinal mass and a persistent cough lasting for a few years. Based on the clinical history and immunological analysis, he was diagnosed with Good's syndrome. He was being managed conservatively with immunoglobulin until he underwent a thymectomy. Subsequently, he developed his first pneumonia. His conditions gradually worsened despite the initiation of IgRT. He was diagnosed to have hypersensitivity pneumonitis based on strong exposure history, consistent radiological images, and good clinical response to antigen avoidance and steroid therapy. To our knowledge, this is the first case of Good's syndrome with hypersensitivity pneumonitis that was unmasked after immune augmentation by the initiation of IgRT. Moreover, surgical intervention should not be considered unless unavoidable. Additionally, close clinical monitoring and laboratory testing are indicated, and IgRT should be considered when the patient begins to exhibit symptoms to prevent severe infections.