Microscopic Description and Lab Work-Up

Histology:  Large pleomorphic neoplastic cells; predominant small mature lymphocytes

Immunostain:  Positive for CD45, CD20, and PAX-5. Negative for myogenin, CD3, CD15, CD30, CD99, and ALK-1.

Flow-cytometry: Due to relative small proportion of the neoplastic cells, flow cytometry often show normal immunophenotype.  Thus, the flow cytometric results are often not diagnostic for T-cell/histiocyte-rich large B-cell lymphoma.

(T-cell/histiocyte-rich large B-cell lymphoma)