The Journal of Thoracic and Cardiovascular Surgery, Vol 90, 351-360, Copyright © 1985 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Electron microscopy in selection of patients with small cell carcinoma of the lung for medical versus surgical therapy
JD Iglehart, WG Wolfe, WB Vernon, JD Shelburne and DC Sabiston Jr
Fifty-one cases of small cell carcinoma of the lung were studied by
electron microscopy in order to determine if ultrastructural subsets could
be found and if these subsets predicted clinical behavior. All of these
cases were considered bona fide small cell carcinoma of the lung by light
microscopy. Tumors with ultrastructural features of epithelial
differentiation were defined by the presence of well-formed, classic
desmosomes joining adjacent cells and by additional features of squamous or
glandular differentiation. Thirty-one tumors (60%) were considered "typical
oat cell" by electron microscopy and 20 (40%) showed features of epithelial
differentiation. Fifteen (75%) tumors with epithelial features were
considered operable and nine (45%) were resected with curative intent. In
contrast, 26 (84%) tumors considered typical oat cell by electron
microscopy presented with extensive metastatic disease. The cancer-free
5-year actuarial survival rate of patients whose tumors showed features of
epithelial differentiation was 25%. The actuarial survival rate of nine
patients who underwent resection of tumors with epithelial features was 38%
at 5 years. Only one patient whose tumor was considered typical of oat cell
carcinoma by electron microscopy survived 5 years. Our current
recommendation is to remove all clinically resectable pulmonary neoplasms
with the expectation that these localized small cell tumors are likely to
show epithelial features by electron microscopic analysis.