Lymphoplasmacytic lymphoma is an uncommon subtype of non-Hodgkin's lymphoma (NHL) occurring mainly in older people. It results from a neoplastic proliferation of post-germinal centre B cells with some degree of maturation to plasma cells . The term encompasses Waldenström's macroglobulinaemia. Various diagnostic criteria have been proposed [2-4].
The clinical presentation is very variable with some clinical features being typical of lymphoma (hepatomegaly, splenomegaly and lymphadenopathy) and others being the result of the paraprotein that is often present . Patients with a high concentration of an IgM paraprotein may have the clinical presentation of Waldenström's macroglobulinaemia, specifically increased plasma volume and hyperviscosity leading to retinal abnormalities, haemorrhage, cardiac failure and cerebral symptoms. Other patients have clinical features resulting from a paraprotein that is a cold agglutinin (chronic cold haemagglutinin disease) or a cryoglobulin (essential or type I cryoglobulinaemia) or has antibody activity leading to peripheral neuropathy. Autoimmune haemolytic anaemia can occur. Transformation to high-grade lymphoma sometimes occurs.
Haematological and pathological features
There may be anaemia and the blood film often shows increased rouleaux formation; sometimes there are red cell agglutinates or cryoglobulin deposits. The lymphocyte count may be normal or there may be mild lymphocytosis (Figure 7.1). Lymphocytes are small and mature and may show plasmacytoid features - abundant basophilic cytoplasm with a small Golgi zone. Larger cells may be present if transformation occurs (Figure 7.2).
Peripheral blood film from a patient with lymphoplasmacytic lymphoma showing rouleaux and one cell with an eccentric nucleus and an ill-defined Golgi zone. Romanowsky, x 100 objective
Peripheral blood film from a patient with large cell transformation of lymphoplasmacytic lymphoma, showing cells with a high nucleocytoplasmic ratio with a Golgi zone being apparent in two of the three cells. Romanowsky, x 100 objective.
Bone marrow infiltration is characteristically by small lymphocytes, plasmacytoid lymphocytes and plasma cells. Crystals or immunoglobulin inclusions are sometimes present within lymphocytes, the term Russell body being used to indicate a rounded cytoplasmic inclusion and Dutcher body to indicate an apparently intra-nuclear inclusion. Mast cells are often increased. Trephine biopsy shows an interstitial or nodular infiltrate. Lymph node infiltration is diffuse.
A paraprotein is usually present, most often IgM but sometimes IgG or IgA. Bence-Jones protein may be detected in the urine.
The immunophenotype is that of a mature B cell with expression of light chain-restricted surface membrane immunoglobulin (most often IgM without IgD but sometimes IgG or IgA) and pan-B markers such as CD19, CD20, CD22 and CD79b. In addition to surface membrane immunoglobulin, some cells have cytoplasmic immunoglobulin ...