Comparison of the usefulness of histochemistry and ultrastructural cytochemistry in the identification of neuroendocrine neoplasms

Neuroendocrine (NE) neoplasms range from well to poorly differentiated types. These neoplasms usually contain neurosecretory (NS) granules demonstrated by either transmission electron microscopy (TEM) or silver reduction methods. By using the uranaffin reaction, one can differentiate NSG from other membrane-bound organelles. Recently, a variety of antibodies reactive against specific peptides or neurotransmitter substances have been advocated as being diagnostically useful. Using the peroxidase-anti-peroxidase (PAP) or Avidin-Biotin technics, we studied 41 NE neoplasms using anti-sera specific for neuron-specific enolase (NSE), bombesin, adrenocorticotropic hormone (ACTH), calcitonin, and serotonin. All cases were shown to contain NS granules with a positive uranaffin reaction. In all 25 well-differentiated cases, at least one anti-serum gave a positive reaction. NSE was positive in 22 of the 25. In the poorly differentiated group, 7 (43.2%) of 16 were negative for all anti-sera tested. In these negative cases TEM using the uranaffin reaction remains an important diagnostic test.