Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody .CD79a is a disulphide linked heterodimer associated with the membrane-bound immunoglobulin; it appears in the pre-B-lymphocyte stage and persists until the plasma cell development, rendering the majority of normal and neoplastic plasma cells positive for CD79a. CD79a exhibits a membranous stain, but plasma cells may also show a cytoplasmic staining pattern. The expression of CD79a is independent of the expression of CD20 and remains positive after the anti-CD20 immunotherapy. CD79a is used for the diagnosis of B-cell lymphoma, but is positive in a small fraction of T-ALL, AML.