#00066312

Peripheral blood smear of a 57 year old male (Leishman stain, ×1000) shows a plasma cell characterized by eccentric round nucleus, coarse clumped chromatin, and abundant basophilic cytoplasm with a perinuclear hof. An adjacent small mature lymphocyte is also noted.

In correlation with laboratory findings: bone marrow aspirate and biopsy demonstrate hypercellular marrow with increased lymphoid cells (25–40%) and plasma cells (~10%); flow cytometry shows CD5-negative, CD10-negative mature B-cell population with plasmacytoid features; serum protein electrophoresis reveals an M-band in the beta-2/gamma region; immunofixation confirms monoclonal IgM with lambda light chain restriction; FISH for CLL panel and karyotyping are normal. Overall features are consistent with bone marrow involvement by lymphoplasmacytic lymphoma (IgM lambda monoclonal gammopathy).