Intracranial metastases of induced lung carcinomas in rats.

Through 25 weekly subcutaneous injections of dipentylnitrosamine (DPNA), metastasizing lung carcinomas were induced in 56 Hann: Wistar rats. Among them nine animals had intracranial metastases. Four metastases were localized in the pituitary, three in the choroid plexus of the IIIrd ventricle, one in the choroid plexus of the IVth ventricle, and one in the brain-stem. Thus, the preferential sites of intracranial metastasis were the choroid plexus of the ventricles and the pituitary. No metastatic spread was found in the cerebral hemisphere. Five of the metastatic tumours resembled the primary pulmonary adenocarcinoma. In the other four, the primary was an adenosquamous carcinoma but only adenocarcinomatous components were present in the metastasis.