The incidence and forms of cerebral amyloid angiopathy were studied in 15 cases of Alzheimer's disease using Congo red staining and polarization. Thirteen cases showed slight to severe involvement; two contained no amyloid vascular degeneration. There was a correlation between the presence of amyloid-rich plaques and cerebral amyloid angiopathy (especially the plaque-like angiopathy) but no correlation with "amyloid-poor" senile plaques or Alzheimer's neurofibrillary degeneration.

Fifteen cases of metastatic brain tumors associated with massive subarachnoid, intracerebral, or intraventricular hemorrhage or a combination thereof are reported. Four patients had multiple bleeding cerebral metastasis. In 10 patients, stroke was the first manifestation of the neoplastic disease. It is concluded that metastases of choriocarcinoma, melanoma, and bronchogenic carcinoma are most prone to massive bleeding. The average survival from the beginning of neurologic symptoms was 65 days, but in seven patients, it was 11 days or less. Surgery seems to be beneficial in selected patients. Massive hemorrhage was a complication in 14 percent of our patients with metastases to brain versus 0.8 percent of those with gliomas.

We demonstrated senile plaques with glial fibrillary acidic protein (GFAP) stain in prefrontal and parietal cortex and in hippocampus of 3 cases of Alzheimer's disease. A plaque seen with GFAP appeared as a nearly round, spot-like brown blush consisting of numerous fine astrocytic processes, usually surrounded by single or, more often, several astrocytic cell bodies and their thick processes. Some plaques were virtually wrapped by these processes which also penetrated to the core, often directly touching the amyloid deposit. We never saw the plaque-type astrocytic grouping and spot-like blushes in the cortex of younger nondemented controls who were plaque negative. Our observations stress the importance of the astrocyte in plaque formation, either as primary or early secondary reactions. The focal glial reaction, without the neuritic component, possibly may precede neuritic change and relate to subminimal amyloid deposits or to some other undefined change.

✓ A solitary intraspinal, extradural melanotic tumor was subtotally resected in a 59-year-old man who had a 17-year history of radicular pain and later evidence of progressive spinal cord compression. The neoplasm revealed the histological features of a benign nerve sheath tumor with massive but uneven melanin production. In electron micrographs the tumor cells contained masses of melanosomes of the type seen in normal skin melanocytes and in B type melanocarcinomas. In the 16-month postoperative period there has been only minimal radiological indication of local recurrence and no metastases.

A case of solitary intracranial plasmacytoma (SIP) spreading from the tentorium toward the right middle and posterior fossae is reported. A particular clinical finding was the presence of an abnormal IgG lambda type in both cerebrospinal fluid (CSF) and serum, which disappeared after partial removal of the tumor followed by radiation therapy. The light and electron microscopical study revealed that the tumor was composed mainly of mature plasma cells. Peculiar deposits of amyloid with a crystaloid plaque‐like morphology were scattered throughout tumor tissue; also the tumor vessels showed amyloid infiltrations. The immunohistochemical study confirmed that the tumor was composed of a population of plasma cells producing a single monoclonal immunoglobulin. The findings of this case were compared to those of the few previously reported SIP.