Stereotactic surgery: the early years.

ALTHOUGH STEREOTACTIC SURGERY was conceived at the turn of the 20th century, human applications did not gain momentum until the 1950s. Modern stereotactic surgery, as currently practiced, has rapidly developed in the past decade with computer assistance obviating the need for invasive localization techniques and ultimately leading to the development of frameless instruments. Applications of these techniques have also greatly expanded the use of stereotactic methods beyond functional neurosurgery.

Enterogenous cyst of the orbital apex and superior orbital fissure.

Background: Enterogenous cysts of the central nervous system are rare congenital tumors with a single layer of mucin-secreting epithelial cells resembling gastrointestinal epithelium. The tumor is located most commonly at lower cervical and cervicothoracic spinal levels; only 22 intracranial cases have been reported. To the authors knowledge, this entity has not been described in the orbit.

Mesenchymal chondrosarcoma of the orbit. Report of three new cases and review of the literature.

Background: Extraskeletal mesenchymal chondrosarcoma is a rare tumor characterized by undifferentiated mesenchymal cells with islands of mature hyaline cartilage. Considering all sites, long-term survival is approximately 30%. Only seven cases of orbital mesenchymal chondrosarcoma have been reported.

Nevus of Ota and leptomeningeal melanocytic lesions.

Two patients with congenital nevus of Ota developed intracranial malignant melanocytic tumors. One had a localized tumor that resembled a melanocytoma, but the other had a more highly malignant tumor that diffusely seeded the leptomeninges. There are 10 prior cases in the world literature.