A decrease below normal in the concentration of the blood platelets. This condition refers to lowering of platelets in the blood and if severe, it can cause bleeding. In cancer patients, it is normally due to chemotherapy or radiation therapy and is due to impaired production of the platelets from the bone marrow.
Meningeal infiltration results in increasing intracranial pressure with papilledema and cranial nerve palsies. Bone marrow infiltration with replacement of normal hematopoiesis causes anemia, thrombocytopenia, and granulocytopenia.