Light microscopical and fluorescence histochemical observations on the endocrinological activity of human pulmonary...

Light microscopical histochemical methods known to demonstrate the hormone storage granules of the hypophyseal ACTH/MSH cells were applied to study 14 oat cell carcinomas of human lung with special reference to assessment of the applicability of these techniques in the detection of the reported endocrinological activity of these tumors. Lead-hematoxylin, masked metachromasia and PAS reactions gave negative results for hormone storage granules in all cases studied. Argyrophilic granules were found in two tumors. The above methods, thus, were interpreted to be far too insensitive to be applicable for the demonstration of endocrinological activity. Fluorescence histochemical demonstration of the NH2-terminal tryptophyl-peptides, shown to be present in the hormone storage granules of the hypophyseal ACTH/MSH cells, yeilded positive results in three of the five studied cases. Two of these positive cases were found to have a pronounced adrenal hyperplasia. Conclusion was drawn that the used fluorescence histochemical technique for the demonstration of the NH2-terminal tryptophyl-peptides might offer new possibilities in the diagnosis of obscure human lung tumors, and it might be a valuable aid in the demonstration of the endocrinological activity in general.