The cells of lymphoplasmacytoid lymphoma are B-lymphoid lineage cells that have features of plasma cell differentiation, but in contrast to plasma cells they retain some mature B-cell features. These cells have the capability to secrete antibody, usually an IgM type.
- Typically, LPL cells resemble mature lymphocytes but with features of plasma cells
- The nucleus is generally round and not indented or convoluted
- A Golgi body may be visible as a pale perinuclear area
- Chromatin is condensed and mature
- Some cells may resemble normal lymphocytes or plasma cells
- Rouleaux or background staining may be very pronounced
Lymphoplasmacytoid cells in blood may be difficult to confidently distinguish from plasma cell leukaemia solely by morphological appearance. Similar to myeloma, there may be heavy background protein staining and rouleaux (sometimes more pronounced than in myeloma), but this may also be absent. Typically, as in this case, the cells resemble normal lymphocytes but with an eccentrically placed nucleus and significant basophilic or pale cytoplasm. Often there is a mixture of morphological forms, with some cells closely resembling normal lymphocytes rather than plasma cells. The number of abnormal circulating cells is rarely high.
IMMUNOPHENOTYPIC RECOGNITION OF LYMPHOPLASMACYTOID CELLS
The purpose of immunophenotyping in LPL is generally to identify the malignant cells and to suggest the correct diagnosis. In general terms, immunophenotyping may suggest the diagnosis but is rarely definitive. Diagnosis is often confirmed by reference to clinical and morphological features or histopathology. Molecular testing may also have value in confirming diagnosis.