What is the role of bone marrow exam in the workup of pediatric acute myelocytic leukemia (AML)?

Updated: Sep 12, 2017
  • Author: Mark E Weinblatt, MD; Chief Editor: Jennifer Reikes Willert, MD  more...
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Answer

Bone marrow examination is necessary to establish the diagnosis of acute myeloid leukemia. The sample is examined under the microscope, at which time the percentage of different cells is tabulated. The hallmark of leukemia is the presence of a high proportion of primitive cells and a paucity of normal hematopoietic elements.

Bone marrow aspirates and biopsy samples demonstrate the characteristic replacement of normal marrow elements with the monotonous sheets of leukemic blasts.

The preferred site for retrieving marrow is the iliac crest, either anterior or posterior. The tibia may be an alternative source of marrow for diagnostic purposes in infants, although it is rarely required as a preferred site. In rare cases, a sternal biopsy is necessary; this can sometimes be required in children with extensive marrow fibrosis. The sternal site is generally more painful and entails the risk of heart damage if the needle penetrates deeply beyond the sternal bone.

Although bone marrow aspiration is usually sufficient to establish the diagnosis and to follow up on the progress of the disease, a core biopsy may be necessary if one encounters a "dry tap." This can happen when a marrow is heavily infiltrated or when significant fibrosis of the bone marrow is present.

Biopsy is necessary to gauge the cellularity of a marrow specimen and was the former standard during follow-up to aid subsequent therapeutic decisions. However, biopsy is now less commonly used, since the disease status can usually be evaluated with marrow aspirations and immunologic and cytogenetic testing.


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