PROGESTERONE RECEPTORS IN ARACHNOID CYSTS - AN IMMUNOCYTOCHEMICAL STUDY IN 2 CASES

We report 2 cases of arachnoid cysts, one with a retrocerebellar and t he other with a left temporal localization, in which immunohistochemic al studies had been conducted. The results of the immunohistochemistry on the presence of carcino-embryonic antigen (CEA) and glial fibrilla ry acidic protein (GFAP), and of the scanning- and transmission electr on microscopy revealed the cyst lining to be identical to subdural neu rothelium. Progesterone receptors were found in the nuclei of cells li ning the cyst, which also suggests the similarity of the cyst lining t o arachnoid granulations and meningiomas as derivatives of subdural ne urothelium, which also possess progesterone receptors.