A comparative study of vascular proliferation in brain metastasis of lung carcinomas.

Because of the marked vascular proliferation seen in brain metastases of small cell carcinoma of the lung (SCCL), we studied the morphometric and immunohistochemical characteristics of proliferating vessels in metastases from 20 autopsy cases of SCCL with brain metastasis. These were compared with those in surgically resected brain metastases of lung carcinomas, including 6 cases of SCCL, 19 cases of adenocarcinoma and 5 cases of squamous cell carcinoma. Angiogenesis in the tumours was scored by the microscopic angiogenesis grading system (MAGS). The MAGS score for autopsy and surgical metastatic lesions was highest in SCCL. Histologically, many vascular glomeruloid structures were formed in the brain metastases of SCCL, and immunohistochemistry revealed that these lesions were composed of proliferating endothelial cells and pericyte/smooth muscle cells. Immunostaining for basic fibroblast growth factor, a potent angiogenic factor, showed immunoreactivity in the tumour cells, regardless of histological type, and in the surrounding glial cells. Complex autocrine and paracrine phenomena participate in the development of metastatic cerebral lesions with vascular proliferation.