[Leptomeningeal carcinomatosis following 27 years remission from breast cancer with epidermoid: a case report].

We herein report a patient with leptomeningeal carcinomatosis (LC) in long-term remission from breast cancer, co-existing with a posterior fossa epidermoid and an increase in the serum CA19-9 level which complicated the diagnosis. A 59-year-old woman underwent a left mastectomy due to breast cancer 27 years ago. She was admitted to our hospital suffering from a headache and diplopia. Her serum CA19-9 level on admission was elevated, and diffusion weighted images showed a high-intensity tumor in the prepontine and left cerebello-pontine cistern. A left lateral suboccipital craniotomy with endoscopic assistance was performed for tissue sampling. The pathological diagnosis was an epidermoid and LC from breast cancer. She died of progression of leptomeningeal carcinomatosis 31 days after surgery. LC alone following long-term remission from breast cancer is extremely rare. Meningeal irritation co-existing with an epidermoid mimicking chemical meningitis is even rarer. Pathological confirmation is required for such rare cases.