小脳出血を契機に発見された急性骨髄性白血病(FAB分類のM4)の1例

Abstract

A 41-year-old man was admitted to our hospital on November 10，1993，complaining of sudden severe headache with vomiting followed by unconsciousness. Emergency brain CT showed massive hemorrhage in the right cerebellar hemisphere，obstructive hydrocephalus and a low density area in the brain stem secondary to compression. Laboratory findings at admission included a hematocrit level of 32.1%，leukocyte count of 109,000/μl with 42% consisting of blast cells，and a platelet count of 18,000/μl. The hemostatic tests were normal except for a prolonged bleeding time. Bone marrow aspiration demonstrated a nuclear cell count of 1,110,000/μl with 43.8% myeloblasts and 21.8% monocytes. Cerebrospinal fluid contained many blast cells. He was diagnosed as having acute myeloblastic leukemia (M 4). Cases of AML detected from intracranial hemorrhage are extremely rare and，to the best of our knowledge，the present case is the first reported case of M 4 detected from intracranial hemorrhage. Regarding the location of the hemorrhage，almost all cases with intracranial hemorrhage were detected from supratentrial hemorrhage，but the present case is the fist reported case detected from cerebellar hemorrhage. The main cause of cerebellar hemorrhage in his case is considered to be invasion of blast cells to the vascular wall. Hyperleukocytosis and thrombocytopenia may have promoted the cerebellar hemorrhage in this case.