Description: Common acute lymphoblastic leukemia antigen (CALLA / CD10) is a useful marker for the characterization of childhood leukemia and B cell lymphomas. This antibody reacts with antigen of lymphoblastic, Burkitt’s, and follicular lymphomas; and chronic myelocytic leukemia. Also, Anti-CD10 detects the antigen of glomerular epithelial cells and the brush border of the proximal tubules; this characteristic may be helpful in interpreting renal ontogenesis in conjunction with other markers. Other non-lymphoid cells that are reactive with CD10 are breast myoepithelial cells, bile canaliculi, neutrophils and small population of bone marrow cells, fetal small intestine epithelium, and normal fibroblasts. Recently Anti-CD10 has been used to classify follicular thyroid lesions.