Bone Marrow Examination See Also Chapter

A bone marrow aspiration and core biopsy are required for determining the extent and the histo-logic pattern of myeloma cell infiltration. The percent myeloma cells in the marrow should be enumerated. In selected cases, immunocytological studies, most commonly using immunoperoxidase staining, are performed for demonstrating light-chain restriction in monoclonal plasma cells. Other markers, such as Ki-67,112 can be assessed. Optional flow cytometric study of the bone marrow is helpful in detailed characterization of the malignant myeloma cells. The nuclear ploidy, S-phase fraction, the expression of B-cell differentiation antigens, adhesion molecules, and occasionally the myeloid markers are of some prognostic interest. If available, a plasma cell labeling index, usually by bro-modeoxyuridine labeling, should be obtained for its prognostic importance.30 Cytogenetic and fluorescence in situ hybridization analyses for numeric and structural abnormalities and for specific rearrangement of chromosomes should be requested whenever possible. The cytogenetic analysis of myeloma cells has significant prognostic value and provides a basis for a molecularly based classification of myeloma (Chapters 80 and 81). Abnormalities in chromosome 13 are particularly ominous.113

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