ALVEOLAR CELL HYPERPLASIA IN ASSOCIATION WITH ADENOCARCINOMA OF LUNG

We studied 41 patients, 22 men and 19 women, with surgically resected adenocarcinoma (AD) of the lung, to determine the frequencies of assoc iated alveolar cell hyperplasia (AGH) and atypical alveolar cell hyper plasia (AACH), and to define the immunohistochemical profiles (IHP) of the AD, AGH, and AACH. The criteria used to look for ACH included a s ingle row of cuboidal cells along alveolar walls, cell morphology dist inct from bronchiolar epithelium, and the absence of chronic inflammat ion. AACH was considered whenever nuclear size was double the size of neighboring ACH and/or in cases with marked nuclear irregularity or hy perchromatism. ACH was identified in 24 of the 41 cases of AD. AACH wa s further demonstrated in six of the 24 cases of AGH. Twenty-three of the 24 cases of ACH were suitable for IHP. The tumors yielded positive results in 23/23, 22/23, 17/23, 22/23, and 18/23 cases when stained w ith Cam 5.2, AE1/AE3, Leu M-1, CEA, and B72.3, respectively. ACH react ed positively in 17/23, 17/23, 0/23, 4/22, and 1/23 cases stained with Cam 5.2, AE1/AE3, Leu M-1, CEA, and B72.3, respectively. AACH reacted positively in 6/6, 6/6, 0/6, 1/6, and 0/6 cases stained with Cam 5.2, AE1/AE3, Leu M-1, CEA, and B72.3, respectively. These findings sugges t that ACH and AACH are common features found in 24 and six of the 41 cases of AD, respectively. The significance of this finding is not kno wn, but it is possible that ACH/AACH may represent precursor changes s imilar to the bronchial epithelial dysplasia described in squamous cel l carcinoma of the lung. Our findings further suggest that AD will alm ost always be immunoreactive for at least four of the five tested mark ers. Conversely, a pattern showing positive immunostaining for Cam 5.2 and AE1/AE3, and negative immunostaining for Leu M-1, CEA, and B72.3 may be useful in the recognition of ACH and/or AACH. However, these im munostains do not appear to be useful in distinguishing ACH from AACH.