Ultrastructure of Well-Differentiated Adenocarcinomas of the Lung with Special Reference to Bronchioloalveolar Carcinoma

Abstract

The cytologic phenotypes of 20 well-differentiated pulmonary adenocarcinomas were determined by electron microscopy. On examination of more than 100 cells in each case, the tumors were classified according to the predominant cell types. Nine cases (45%) were of mucous cell type, further divided into 7 cases of bronchial surface epithelial cell type, 1 case of bronchial gland cell type, and 1 case of metaplastic bronchiolar goblet cell type. The remainder included 5 cases (25%) of Clara cell type, 2 cases (10%) of type II cell type, and 4 cases (20%) of mixed cell type. The predominant histologic pattern by light microscopy was "typically" bronchioloalveolar (Manning et al.'s type 1) in the metaplastic goblet cell tumor and papillary in most Clara cell-type tumors, while it was glandular in bronchial surface and bronchial gland cell types, although variable in type II cell or mixed cell type. Therefore, bronchioloalveolar carcinomas, when histologically defined inclusive of papillary tumors, present cytologic phenotypes also related to the bronchioloalveolar epithelium, i.e., metaplastic goblet or Clara or type II cell subtypes, which is in accordance with some previous reports. These tumors could be distinguished from the other (glandular) adenocarcinomas that show primarily bronchial mucous cell differentiation.

Thyroid transcription factor-1 is highly sensitive and specific in differentiating metastatic pulmonary from extrapulmonary adenocarcinoma in effusion fluid cytology specimens

“…However, the procedure is more tedious than conventional immunohistochemic study. Conversely, lamellar bodies are visible under electron microscopy in some cases of pulmonary adenocarcinoma, especially bronchioloalveolar carcinoma 33. However, the usefulness of electron microscopy in cytology cell block materials is limited due to poor artifact preservation.…”

Lung stem cells

“…Several theories of lung tumour origins try to resolve the many phenotypes displayed by these neoplasms. Further details are to be found in recent reviews of the subject: (Baylin 1985;Barsky et al 1994;Colby et al 1995;Eimoto et al 1985;Gatter et al 1985;Marchevsky 1990b;Wright 1990;Mabry et al 1991;Gatter & Dunhill 1992;Ratcliffe 1992). These range from the pluripotent stem cell hypothesis, where phenotypes are produced by differentiation (Mü ller & Fisseler-Eckhoff 1989), to the multiple primary hypothesis, a possibility inferred from analyses of aneuploidy in different foci of the same tumour mass (Barsky et al 1994;Colby et al 1995).…”

Angiogenesis and extracellular matrix remodelling in bronchioloalveolar carcinomas: distinctive patterns in mucinous and non‐mucinous tumours

“…As in other adenocarcinomas, myofibroblasts probably play a central role in this process by secreting growth factors and cytokines, as confirmed by their presence in large numbers in all NM‐BACs 20–23 . The NM‐BAC microenvironment parallels that described in most adenocarcinomas, including conventional invasive lung adenocarcinomas, in which the production of a tumour‐associated stroma occurs to support both the neoplastic cells and the new vessels 13,24–26 . It is conceivable that NM‐BAC represents an early stage of development of invasive adenocarcinoma, excised before the occurrence of parenchymal lung infiltration or metastasis.…”