Recommended positive control：tonsil, lymph node etc.
Staining pattern: Cytoplasmic.
One of the most reliable B-cell marker, recognizing wider maturation phases of B-cell including blasts and plasma cells.
Positive in B-cell neoplasms very specifically. Plasma cell neoplasm are also positive (about half of cases).
Especially helpful for diagnosis of B-lymphoblastic lymphoma and small cell lymphoma, frequently negative for CD20.
Note: T lymphoblastic lymphoma may show positive for CD79a. (John KC Chan. Tumors in lymphoretiucular system in Flercher et al. Diagnostic histopathology of tumors p1106)
Note: Unlike CD20, diffuse dense CD79a-positive pattern can be seen in inflammatory process, especially plasma cell-rich lesions.