Endodermal sinus tumor originating in the region of the pineal gland. Ultrastructural and immunohistochemical study

This is a case report of an endodermal sinus tumor (EST) arising in the pineal region of a 19-year-old girl (first case studied by electron microscopy). The ultrastructure of the tumor was similar to that of the previously reported cases of EST of ovaries, mediastinum, and sacrococcygeal area. A characteristic basement membrane-like material has been identified within endoplasmic reticulum of tumor cells and in intercellular spaces. Alphafetoprotein has been detected in the spinal fluid of the patient by radioimmunoassays and within tumor tissue by immunohistochemical techniques. Combination therapy consisting of radiation, surgical decompression, chemotherapy (BCNU), and prednisone has been employed in the treatment of this patient without significant benefit. The patient expired three months after the surgery, no autopsy was obtained.