History History may reveal information that suggests malignant and nonmalignant causes of a solitary pulmonary nodule and includes Current or past cigarette smoking History of cancer or an autoimmune disorder Occupational risk factors for cancer (eg, exposure to asbestos, vinyl chloride, radon) Travel to, or living in, areas with endemic mycosis or a high prevalence of tuberculosis (TB) Risk factors for opportunistic infections (eg, HIV, immune deficiency) Older age, cigarette smoking, and history of cancer all increase the probability of cancer and are used along with the nodule diameter to estimate likelihood ratios for cancer.