Tumor cell spread into leptomeningeal structures of the brain and/or spine.
Leptomeningeal spreading is a major disease complication in primary central nervous system (CNS) tumors; in solid tumors outside the CNS such as breast cancer, lung cancer, gastrointestinal cancer, and melanoma; and in hematological malignancies. Leptomeningeal dissemination can occur at initial diagnosis (primary dissemination) or during the course of the disease following initial therapy (secondary dissemination), but it is usually a late manifestation of malignant diseases and almost always associated with active tumor disease. Primary leptomeningeal disease is found mostly in primary brain tumors, sarcomas, neuroblastomas, lymphomas, and leukemia. Secondary dissemination occurs mostly in lung and breast carcinomas but also in leukemia and lymphomas and...