• isolated small lesions in the lungs are seen in 1- and 2-month-old mice and an increase in lesion size is seen with age
• however, no lesions are seen in other organs, including brain, liver, kidney, intestine, and muscle and no metastases are seen
• lesions are atypical papillary bronchiolar hyperplasia, solid and papillary adenomas, adenomas with atypical cytologic features, atypical papillary bronchiolar hyperplasia adjacent to adenomas, and adenoncarcinoma
• the main lesions are epithelial hyperplasia in the early stage and adenomas in the middle and late stages
• early lung lesions exhibit a Clara cell phenotype indicating that lesions come from Clara Cells of conducting airways and more advanced pathologies show an alveolar type II cell phenotype
• weekly exposure to aerosolized nontypable Haemophilus influenzae lysate results in an increase in total lung tumor burden