Immunohistochemical demonstration of neuron-specific enolase in neoplasms of the CNS and other tissues.

In normal conditions, neuron-specific enolase (NSE) is histochemically demonstrable only in neurons and cells of the amine precursor uptake and decarboxylation (APUD) system. This has been found not to be true for neoplastic cells. Several types of CNS tumors, including glioblastoma, astrocytoma, oligodendroglioma, ependymoma, medulloblastoma, pineocytoma , meningioma, and choroid plexus papilloma, focally stained positively for NSE. Reactive astrocytes were also frequently positive. In the peripheral nervous system, neuroblastoma, ganglioneuroma, and paraganglioma stained positively for NSE. A number of non-APUD tumors were focally positive. These included schwannoma, carcinoma and fibroadenoma of the breast, renal cell carcinoma, giant cell tumor of the tendon sheath, and chordoma. Caution should be exercised in relying on the immunohistochemical demonstration of NSE as a diagnostic marker in those tumors that do not belong to the APUD cell system. It seems of little value as evidence of differentiation in CNS tumors.