Leukemia patients' coughing is not directly caused by the leukemia itself, but often due to pulmonary inflammation that commonly accompanies leukemia, leading to symptoms such as coughing, phlegm, and chest pain. Due to a reduced count of normal neutrophils, leukemia patients have low resistance and poor immunity, making them highly susceptible to secondary infections, particularly pulmonary infections. Following a pulmonary infection, whether bacterial, fungal, or viral, patients may experience symptoms including coughing, severe cases may involve coughing up phlegm, chest pain, and breathing difficulties.