Expression of chromogranin a protein and messenger RNA and tyrosine hydroxylase protein in paraffin-embedded sections of neuroendocrine neoplasms.

Forty-three neuroendocrine neoplasms were analyzed by immunohistochemistry for tyrosine hydroxylase and chrornogranin A and by in situ hybridization (ISH) for chrornogranin A messenger RNA (mRNA) using formalin-fixed paraffin-embedded tissue sections. These included pheochromocytomas (7), medullary thyroid carcinomas (5), small-cell lung carcinomas (5), olfactory neuroblastomas (5), neuroblastomas (10), ganglioneuroblastomas (5), and ganglioneuromas (6). Tyrosine hydroxylase was detected in all groups of tumors except the small-cell lung carcinomas, whereas immunoreactivity for chromogranin A protein was detected in all groups. ISH analysis for chromogranin A mRNA agreed with the immunohistochemical findings. Beta-actin mRNA was present diffusely in tumor cells, confirming the preservation of another mRNA. There was no apparent relationship between protein or mRNA expression and the degree of differentiation in the 21 neuroblastic tumors. These results indicate that tyrosine hydroxylase may be another useful marker for neuroblastic tumors and that chromogranin A mRNA can be detected in routinely processed formalin-fixed paraffin-embedded tissue sections.