Anti-CD68 marks cells of monocyte/macrophage lineage. This antibody is capable of staining monocytes, Kupffer cells, osteoclasts, granulocytes and their precursors; lymphomas are negative or show few granules. This antibody may be useful for the identification of myelomonocytic and histiocytic tumors. Since this detects a formalin-resistant epitope that may be associated with lysosomal granules, other lysosome-rich cells may also stain.^1-3 It is often tested together with AACT and Lysozyme to improve its diagnostic accuracy.