Procedure

• fixation: routinely fixed immediately in 10% buffered formalin or B5 fixative. Other fixatives in use include Zenker's fixative and 2% formol acetic acid.

• fixation time: 48-72 hrs. Further fixation results in loss of antigenicity and lesser fixation yields poor morphology.

• decalcification: should be carefully controlled and limited to softening the bone enough to permit even sectioning.

• embedding: the choice between plastic resin and paraffin wax largely depends on individual laboratory preference. The morphology is better preserved in plastic-embedded semi-thin sections but many pathologists are unfamiliar with this preparation. The advantage of paraffin embedding lies in familiarity, cost effectiveness and antigen preservation that allows for better immunohistochemistry.

• sectioning: 2-4 ^m sections are ideal for good morphological detail.

• staining: both Giemsa and H&E are essential for routine interpretation. Additional stains for iron and reticulin are commonly used.

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