Immunohistological studies of nonthyroidal calcitonin-producing tumors.

A series of oat cell carcinomas of the lung and some corresponding sputum specimens were studied along with other tumors by immunoperoxidase histology for the presence of calcitonin, beta-endorphin, and ACTH. Sixteen of 31 tissues were positive for calcitonin, 12 of 14 were positive for beta-endorphin, and 11 of 14 were positive for ACTH immunoreactivity. Many tissues contained all 3 peptides, and in some sections these peptide immunoreactivities appeared to be present in the same cells. These studies suggest that there is a releationship in oat cell carcinoma of the lung and other tumors among the 3 peptides, although the basis of this relationship is not clear.