A lack of diffuse pleural involvement, presence of a gross circumscription and encapsulation, lack of necrosis and infiltrative features such as capsular or lymphovascular invasion, an absence of marked cytologic atypia, and a proliferation rate of <2% as assessed by a MIB-1 (Ki67) immunostain (Figure 3(d)) all favored a diagnosis of adenomatoid tumor. This evidence concerns the gene MKI67 and neoplasm.