Tumoral cells with characteristic lymphoplasmacytoid nuclear and cytoplasmic features showed an intense stainning with pan-B cell markers like CD-45A (L26 x 400).

Non tumoral small lymphocytes were frequently observed. They were demonstrated with pan-T cell markers like CD45RO (UCHL-1 x 400).

Neoplastic lymphocytes showed monoclonality in light chain immunoglobulin production. Only stainning for Kappa light chain was achieved (Kappa light chain x 630).

Only scarce mature plasma cells were found to be positive with Lambda light chain. Note a tumoral cell in mitosis in upper right corner (Lambda light chain x 400).