Hypersensitivity Pneumonitis: The Diagnosis Lies in History.

Hypersensitivity pneumonitis (HP)/extrinsic allergic alveolitis (EAA) is defined as a response of lungs to inhaled organic and inorganic substances. This disease is relatively rare, comprising 2% of cases in the category of interstitial lung diseases. Here, we discuss a case of 61-year-old female, who presented with sudden onset breathlessness, with bilateral coarse crackles on physical examination, initially thought to be due to heart failure or atypical pneumonia, but later diagnosed as HP. She was managed initially with antibiotics but due to poor response, steroids were introduced which led to significant improvement. This report emphasizes the importance of exposure history of substances that are toxic, lack of specificity of clinical manifestations, importance of invasive methods for diagnosis, and poor response to therapy in case of delayed diagnosis.