"Pure" meningeal carcinomatosis as the autopsy-proven sole manifestation of an undetected cancer.

Meningeal carcinomatosis (MC) was diagnosed in a 37-year-old woman, based on the finding of neoplastic cells in the cerebrospinal fluid. The patient had no relevant antecedent except the resection of a breast "nodule" at the age of 20. No primary cancer nor other metastases were detected, even at autopsy. Histopathology, immunocytochemistry and electron microscopy confirmed pure leptomeningeal infiltration by poorly differentiated adenoepithelial cancer. This case includes several unusual features and raises the possibility of an extremely long-lasting interval between an unrecognized primary (breast?) carcinoma and MC.