Acute aggravation of subdural fluid collection associated with dural metastasis of malignant neoplasms: case report and review of the literature.

A 63-year-old woman was admitted to our hospital with serious headache and vomiting. Five months before admission, she had undergone surgery for a primary advanced gastric cancer. Neuroradiological examinations revealed subdural fluid collection. We twice performed evacuation of the subdural fluid collection. However, aggravation of her state of consciousness progressed and she passed away. Histological examinations demonstrated that the dural veins were infiltrated by numerous tumor cells that produced mucus; however, ruptured vessels were not found. Furthermore, the subdural fluid collection increased shortly after the initial operation. We infer that the cause of the collection, which was associated with the dural metastasis of malignant tumors, was not only mucin secretion by tumor cells but also a rapid increase in perfusion pressure in the vessels of the dura mater, resulting in extravasation of plasma components into the subdural space. Our case demonstrates that the pathogenetic mechanism that is specific for subdural fluid collection caused by dural metastasis of malignant tumors differs from the mechanism of production of subdural hematoma associated with dural metastasis.