Abstract: Objective To investigate the ultrastructure and histogenesis of intracranial chondroma. The tissue origin of the tumor was studied in combination with the morphological features. Methods 7 cases biopsy specimens of chondroma in middle cranial fossa were examined with transmission electron microscopy. Results Most of intracranial chondroma were located at the position of junctura cartilaginea of basicranial skeleton. It was difficult to make a definite diagnosis by means of neuroradiologic examination. Ultrapathology confirmed the tumor tissue consisted of untypical cartilager cells. Electron microscope observed the tissue structure disturbance of chondroma and polymorphic morphology of tumor cells as well as a lot of processes and microvillus on the cell membrane surface. The tumor cells was rich of cytoplasma and a large numbers of juncturae, rough endoplasmic reticulum expansion along with the polymorphic nucleus. There are a lot of homogeneous mucous in the matrix. Conclusion The ultrastructure characteristics support that the origin of intracranial chondroma is brephic embryonic rest of osteoprogenitor cells in the basicranial periost.

Key words: intracranial chondroma, electron microscope, ultrapathology