X.C.001

CD3 immunostain of T lymphocytes. This reddish-brown reaction product identifies T lymphocytes. This image shows staining of a background of polyclonal reactive T lymphocytes amidst the centroblasts of large B cell lymphoma (e.g., asterisks).

X.C.002

CD10 immunostain of germinal center B lymphocytes. This reddish-brown reaction product identifies, in this case, neoplastic follicular B cells, an immunophenotype that resembles normal germinal center cells.

X.C.003

CD15 immunostain of Reed-Sternberg cells. The reddish-brown reaction product stains the cytoplasm of Reed-Sternberg cell (large binucleate cell in center of field) (arrow) and Reed-Sternberg variant cell (smaller mononuclear cells with reddish-brown reaction product in the cytoplasm) (asterisk) in a case of classical Hodgkin lymphoma.

X.C.004

CD20 immunostain of B lymphocytes. The reddish-brown reaction product stains neoplastic lymphocytes with a B cell phenotype. Reactive T lymphocytes are unstained.

X.C.005

CD30 immunostain of Reed-Sternberg cells. This reddish-brown reaction product identifies Reed-Sternberg and Reed-Sternberg variant cells in Hodgkin lymphoma. Note classical binucleate Reed-Sternberg cell (e.g., arrow) and mononuclear variant Reed-Sternberg cells (e.g., asterisk). This immunostain also reacts with anaplastic large cell lymphoma and activated lymphocytes.

X.C.006

CD34 stain for myeloblasts. Marrow biopsy. (A) Marrow shows replacement by monotonous population of blast cells. (B) Anti-CD34 staining of blast cells confirms the myeloblastic nature of the acute leukemia.