Cell incohesiveness and pattern of extension in a rare case of bronchioloalveolar carcinoma

Abstract

A unique case of adenocarcinoma of the lung that showed aerogenous extension is presented. Although the primary focus was the usual invasive bronchioloalveolar carcinoma, the tumor cells were dissociated, floating and filling the alveolar spaces, the bronchioli, and the small bronchi at the periphery of the primary tumor and in every involved area in other lobes of the lung. Massive tumor cells were expectorated in coincidence with the appearance of abnormal densities on chest X-ray films. Ultrastructurally the dissociated tumor cells had numerous microvilli on the cell surface and rarely showed intercellular junctions. The tumor cells also contained well-developed rough and smooth endoplasmic membranes, crista-vesicular-type mitochondria, electron-dense granules, and granules with myelinlike figures. No mucous granules and no Clara-cell-type secretory granules nor lamellar bodies of the type seen in normal granular pneumocytes were seen. From these findings, it was concluded that the tumor cells in this case were rather poorly differentiated but somewhat resembled the hyperplastic cuboidal alveolar cells seen in the damaged lung and that they proliferated freely in airways, presenting aerogenous metastases. The biologic behavior of this tumor might be partly explained by the incohesive nature of the tumor cells.