A case report of meningeal carcinomatosis presenting as rapidly progressive dementia: cytological diagnosis with ancillary immunohistochemistry of cerebrobrospinal fluid cells.

This case underscores that RPD can be a rare but dominant initial feature of MC and highlights the essential role of CSF cytology combined with immunohistochemistry in achieving a definitive diagnosis, especially when neuroimaging is nonspecific and a primary tumor is not detected.