[Metastases of the central nervous system: A prospective study. 2nd Communication: site and distribution patterns of brain metastases].

Among 737 malignant tumors, 93 (12.6%) cases showed metastases within the brain substance. There was no predominance for one of the both hemispheres. However, the cerebellum was a privileged site for metastases (48 out of 93 cases, 51.6%). Multiple metastatic nodules of the brain were found in 65 cases; single metastases occurred 18 times (ratio 3.6 to 1). 11 cases displayed a carcinosis of the leptomeninges and 5 a carcinosis of the brain (table 3). Within the cerebrum we observed 1,060 metastatic nodules (fig. 1). 210 secondary deposits, i.e. one sixth of all nodules, were localized in the cerebellum. Concerning the distribution patterns of the metastases, it is remarkable that an increasing frequency of nodules was seen from the frontal lobes (241) to the parietal (259) and occipital lobes (276), whereas the temporal lobes (146) were significantly less affected. 936 out of a total of 1,270 brain metastases (73.7%) showed a size of the nodules not larger than a pea (table 8.) The source of more than two thirds of all metastatic deposits (875/1,270 = 68.9%) was a carcinoma of the lung (bronchial carcinoma, resp.). With the exception of metastases in the pituitary gland, pineal gland and choroid plexus (compare with the 3rd communication on CNS metastases) 18.6 metastatic brain nodules were observed per lung carcinoma. However, the highest frequency per case with brain metastases was registered in thyroid cancer (40 nodules, table 8).