The Significance Of Elastic Fibers In Diagnosis Of Bronchioloalveolar Carcinoma And Adenocarcinoma Of Lung

Objective To elucidate the histopathological characteristics of the elastic fibers (EFs) in bronchioloalveolar carcinoma(BAC) and adenocarcinoma(AC) of lung. Materials and Methods 66 cases were randomly selected which were initially diagnosed as AC,BAC or AC partly associated with BAG. Other 50 cases, as the contrast, were diagnosed as various diseases of lung. Haematoxylin-Eosin staining method was performed on 10%formalin-fixed and paraffin-embedded, 5 μm cut lung tissue sections. The histological patterns of the lung carcinomas were observed under the light microscope. EFs in the stroma of lung were detected in BAG ,AC and other diseases with the method of Weight's staining. The EFs in the stroma of normal lung, BAG and AC were also observed by transmission electron microscope.Results Among the 66 cases ,30 cases were diagnosed as AC,31 as BAG and 5 as AC partly associated with BAG. According to the histopathology, we divided all the cases into four categories: type A(AC), EF staining negative; type B(Infiltrative BAC), EF staining from positive to strong positive; type C(non-infiltrative BAC), EF staining from positive to strong positive; type D(AC partly associated with BAC), EF staining negative or positive. The results of EF staining were completely different in AC and BAC, so that this method might be a good assistant diagnosis method to distinguish BAC from AC. Thehisto-structures of type B were similar to those of type A, but type B was diagnosed as BAG by EF staining. Type B was a new histological type of BAG with carcinomatous infiltration in stroma, blood vessels and viscus pleura. Type C was non-infiltrative BAG. The results of EF staining in other types of lung cancer were similar to AC. By transmission electron microscope, EFs could be found easily in the stroma of BAG, but rarely be found in the stroma of AC. Conclusions BAG could be distinguished from AC with the histochemical method of EF staining. BAG should be regarded as an independent entity with infiltrative and non-infiltrative types.