Bone marrow necrosis: an entity often overlooked.

Bone marrow necrosis is a poorly understood and frequently an unrecognized finding in routine bone marrow biopsies. Previous reports indicate the incidence of bone marrow necrosis ranges from 0.5 percent (rare) to approximately one-third of all bone marrow biopsies examined. Our studies indicate that the presence of bone marrow necrosis depends on the clinical condition of the patient. Overall, our incidence of bone marrow necrosis was 37 percent of the bone marrow biopsies examined. Of these, 26.4 percent was mild. 7.5 percent moderate, and 3.1 percent severe necrosis. The mechanism in most cases had an identifiable underlying etiology such as a malignancy, or vascular or cytotoxic damage, with a small percentage being unexplained. Bone marrow necrosis is seen across a wide range of conditions, including sickle cell diseases, AIDS, leukemia, lymphoma, metastatic carcinoma, anemia, sepsis, and other systemic diseases. Patients at the extremes of age, less than 20 years and greater than 70 years, usually demonstrate only small foci of necrosis (Grade I). Moderate (Grade II) and severe (Grade III) bone marrow necrosis are often associated with life threatening illnesses, with most of these being hematologic malignancies or bone marrow metastases. The prognosis associated with bone marrow necrosis seems to be dependent on the underlying primary clinical condition regardless of the degree of necrosis observed.