Periodic acid-Schiff-lead hematoxylin as a marker for the endocrine phenotype in human lung tumors.

Periodic acid-Schiff-lead hematoxylin is evaluated for light microscopic diagnosis of pulmonary endocrine cell tumors. Twenty-eight aldehyde-fixed primary human lung tumors were examined by electron microscopy. Fifteen were classified as endocrine (one carcinoid, six small-cell carcinomas, and an "atypical" group of eight with diverse histologies), based on possession of characteristic submicronic, dense-cored cytoplasmic granules. Electron probe analysis in the carcinoid tumor established that dense-cored granules were equivalent to lead hematoxylin-stained granules, which were visible in glycol methacrylate sections as seen on light microscopy. Lead hematoxylin-positive granules were also seen in seven of eight "atypical" tumors, three small cell carcinomas, a glucagonoma, and a chemodectoma. Findings were equivocal in two small cell carcinomas, and negative in all other lung tumors. In overall diagnostic acuity, periodic acid-Schiff-lead hematoxylin equals electron microscopy, surpasses argyrophilia, serotonin fluorescence, and immunolocalization of polypeptide hormones. It is approached only by antineuron-specific enolase immunoreactivity.