The utility of B72.3, carcinoembryonic antigen, and Leu M-1 in cell blocks: An adjunct to fine-needle aspiration diagnosis of bronchioloalveolar carcinoma of the lung

BACKGROUND. The distinction of bronchioloalveolar carcinoma (BAC) from atypical adenomatous hyperplasia (AAH) or reactive alveolar cell hyperplasia (RAH) can be difficult on aspiration cytology, even when cell block preparations are available. The authors evaluated the usefulness of B72.3, carcinoembryonic antigen (CEA), and Leu M-1 immunostains in differentiating BAG, AAH, and RAH. METHODS. Immunostains for B72.3, CEA, and Leu M-1 were performed on cell block sections from 11 lung lesions that were diagnosed cytologically as BAG (6 lesions) and "atypical cells, cannot exclude BAG" (5 lesions). Ten histologic sections of AAH and 8 histologic sections of RAH also were stained. RESULTS. Among the six lesions that had an unequivocal cytologic diagnosis of BAG, all sections were positive for two of three immunostains. Tissue follow-up confirmed BAG in all six lesions. Among the five lesions that were diagnosed as "atypical cells, cannot exclude BAG," four lesions were positive for two of three immunostains, and one lesion was negative for all three immunostains. Subsequent tissue follow-up confirmed BAG in four of these lesions. Follow-up histology of the wedge resection on the lesion in the atypical category that was negative for B72.3, CEA, and Leu M-1 showed only AAH. All 10 lesions that had a histologic diagnosis of AAH and 8 lesions that had a histologic diagnosis RAH were negative for B72.3, CEA, and Leu M-1. CONCLUSIONS. Positive staining for at least 2 immunostains among B72.3, CEA, and Leu M-1 provided strong supportive evidence for the diagnosis of BAC, and a negative result for all 3 immunostains was helpful in excluding BAC and in differentiating BAC from AAH and RAH.