Chiasmal gliomas with spontaneous regression: proliferation and apoptosis

Spontaneous regression of chiasmal gliomas without associated neurofibromatosis has been occasionally described. In this paper we present two patients with chiasmal glioma whose tumors decreased in size during the postoperative course. Neither patient received radiotherapy or chemotherapy. We examined the proliferative activity of the excised tumors by determining the Ki-67 labeling index and searched for apoptotic cells using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method. The Ki-67 labeling index of the tumor of case 1 was 0.63%, and apoptotic cells were detected in some areas. In case 2, the Ki-67 labeling index was 19.5% and a large number of apoptotic cells were evident. As estimated from the respective apoptosis data, our results would indicate that tumor regression may occur when the rate of cell loss is greater than that of tumor growth.