Abstract: To determine the relationship between the ultrapathology characteristic and clinical symptoms, signs of hypothalamic hamartoma, 14 cases of hypothalamic hamartoma were studied. Of them, there are 5 cases with precocious puberty; 4 cases with gelastic epilepsy; other cases with both precocious puberty and gelastic epilepsy. CT or MRI scan showed occupation mass in hypothalamic area. Total surgical resection were done in 14 cases. Biopsy specimen were examined with eptic and electron microscope. Ultrastructural research preved that the hypothalamic hamartoma is composed of neuroectoderm. The tumor parenchymal consisted of neurons and astrocytes. The tumor mesenchyme looked like neuropil. Electron microscopic examination showed that there were Golgi apparatus, microtubules, dense core vesicles and clear vesicles were found in numerous cytoplasm and cell processes. These morphologic features relate to precocious puberty and gelastic epilepsy. It is an important method to diagnosis hypothalamic neuronal hamartoma with eletron microscope technique.

Key words: hypothalamic hamartoma, ultrastructure pathology, electron microscope