This multicenter prospective cohort study will enroll adults who have undergone resection of a primary pulmonary nodule and have residual multiple pulmonary nodules or require routine postoperative pulmonary nodule follow-up. During clinically indicated follow-up visits, a small amount of peripheral venous blood will be collected at the same time as routine blood draws for research CyTOF immune phenotyping and viral imprinting-related serology. The study will not assign participants to treatment, change follow-up schedules, imaging, medication, surgery, or other clinical care. Research laboratory results will not be returned to participants or entered into medical records. The study will describe longitudinal peripheral immune-cell profiles and explore associations among T/B/NK cell phenotypes, T-cell differentiation and senescence/exhaustion markers, viral imprinting markers, and postoperative residual or new pulmonary nodule evolution.