CD10 is a cell surface metallopeptidase, expressed on early lymphoid progenitor cells and on a small subset of immature B cells in bone marrow, but is lost as the cells reach maturation. CD10 is, however, re-expressed on proliferating B cells and mature neutrophils. Various non-lymphoid cells, including bile canaliculi and renal glomerular and tubular epithelial cells are also CD10-positive. The antibody may be a useful aid for classification of Burkitt's lymphoma, follicular lymphoma except grade III, precursor B-cell acute lymphoblastic leukemia, and clear cell renal cell carcinoma. Futhermore, CD10 antibodies may also be a useful aid in the subclassification of the mature T-cell neoplasia subtype and angioimmunoblastic T-cell lymphoma. Anti-CD10, Clone 56C6, is well-suited for use on formalin-fixed tissue sections.