BRONCHIOLOALVEOLAR CARCINOMA - DIAGNOSTIC PITFALLS AND IMMUNOCYTOCHEMICAL CONTRIBUTION

Because bronchioloalveolar carcinoma (BAC) commonly displays bland cyt ologic appearance, there is a good potential for misinterpretation. Th e aim of this study was twofold: one was to identify the most reproduc ible cytomorphologic features to distinguish BAC from conventional lun g adenocarcinoma (CLA) on fine-needle aspiration (FNA), and the other was to investigate the staining characteristics of these two variants of lung carcinoma with P53 tumor suppressor gene immunostain and their potential value in the distinction between the two entities. Cytology records of 13 histologically documented BACs was retrieved: 7 FNA, 3 bronchial washing/bronchial brushing (BW/BB), and 3 scraping smears of surgical specimens. Two cases had both FNA and BW/BB material. Immuno stains for P53 protein, carcinoembryonic antigen (CEA), and Ki67(MIB-1 ) monoclonal antibodies were performed on 13 BACs (FNA cell blocks and tissue) and on 11 FNA cell blocks of CLA. Cytologically, BAC showed u niform cells with abundant, lacy cytoplasm, and bland, folded nuclei a rranged singly, in papillary clusters, and sheets. Immunocytochemicall y, one BAC and one CLA were technically unacceptable. Of the 12 remain ing BAC cases, 10 were reactive with CEA, 9 reactive with Ki67 (>5%), and 4 reactive with P53. Of the 10 remaining CLAs, 9 were positive wit h CEA, 9 were reactive with Ki67 (>5%), and 8 were reactive with P53. We conclude that BAC demonstrates distinctive cytologic features, but difficulty may be encountered with well-differentiated CLA, metastatic adenocarcinoma, and other lesions. Immunocytochemically, CEA and Ki67 do not appear to be discriminate, but P53 may be of value in distingu ishing BAC from CLA. Attention to subtle nuclear changes, characterist ic grouping, cellular arrangement, and P53 reactivity could enable cyt opathologists to accurately diagnose BAC. (C) 1998 Wiley-Liss, Inc.