After fixation, decalcification, and paraffin processing, bone marrow cores are thinly sectioned, usually at 3 microns in thickness and H&E stained. Cutting thin sections allows for appreciation of cellular detail. Five levels are customarily prepared for pathologist evaluation as well as an additional slide stained with Prussian blue for iron storage evaluation. These additional levels allow for successful visualization of focal disease processes. Bone marrow cores allow for the best evaluation of bone marrow cellularity, cellular distribution, and cellular relationships and elements. Cellular morphology in core specimens is optimized when a mercurial fixative is utilized, although the application of such is not discussed in this course.
Bone marrow core biopsy sections allow for appreciation of disease involvement and distribution. Core sections are not optimal for immunoperoxidase staining, as decalcification leads to degeneration of antigens. Optimal length for bone marrow core biopsies is 1-2 cm in length for evaluation of anemia. For evaluation of lymphoma or metastatic carcinoma, a larger core is desirable, usually bilaterally.