What diagnosis is most likely for a patient presenting with night sweats, low-grade fever, and a productive cough with pink-tinged sputum?

The symptoms of night sweats, low-grade fever, and a productive cough with pink-tinged sputum strongly suggest tuberculosis (TB). TB is characterized by a chronic cough that may produce sputum that can be blood-streaked, especially as the illness progresses. Night sweats and fever are also common systemic symptoms associated with TB due to the body's immune response to the infection.

In contrast, while pneumonia can also present with a cough and fever, it typically does not feature the prolonged night sweats seen in TB, and the sputum is often purulent rather than pink-tinged. Asthma usually presents with wheezing, shortness of breath, and tightness in the chest rather than a productive cough with specific sputum characteristics. Lung cancer may present with a cough and weight loss but is less likely to present with night sweats and low-grade fever as primary symptoms when compared to TB. The combination of these symptoms makes tuberculosis the most likely diagnosis in this scenario.