Definition
A neoplasm of small B lymphocytes, plasmacytoid lymphocytes and plasma cells, usually involving bone marrow, lymph nodes and spleen, usually negative for CD5, with a monoclonal serum protein with hyperviscosity or cryoglobulinaemia. Plasmacytoid/plasmacytic variants are excluded.
Epidemiology
A rare disease (1.5% of nodal lymphomas) occurring in the elderly.
Clinical features
There is commonly involvement of bone marrow, spleen and lymph nodes. There may be extranodal involvement of lung, gastrointestinal tract or skin, but most cases previously diagnosed as LPL are MALT lymphomas. The serum monoclonal protein is usually IgM (Waldenström macroglobulinaemia), resulting in hyperviscosity in 10-30% of patients. 10% of patients develop neuropathies. IgM deposition occurs in the skin and GI tract results in diarrhoea. There may be a coagulopathy. Waldenström macroglobulinaemia may also occur with a variety of other B-cell lymphomas; it is not synonymous with LPL.
Histopathology
There is maturation to plasmacytoid cells, but lacking the features of other lymphomas (pseudofollicles, neoplastic follicles, monocytoid B cells).
lymph nodes; the pattern is diffuse or interfollicular, sparing the sinuses. The infiltrate consists of small lymphocytes, plasmacytoid cells lymphocyte-like nuclei with abundant basophilic cytoplasm and plasma cells Immunoblasts, epithelioid histiocytes and mast cells may be present.
bone marrow; nodular or interstitial infiltration.
There may be circulating neoplastic cells, but the count is lower than for CLL
Immunohistochemistry
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negative |
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negative |
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positive |
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negative |
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positive |
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variable |
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positive |
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SIg |
positive, usually IgM, sometimes IgG, rarely IgA |
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50% of cases |
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†: fresh frozen tissue only
Variants
Gamma heavy chain disease: there is secretion of a truncated gamma chain lacking light chain binding sites. Patients are adults with constitutional symptoms, autoimmune manifestations haemolytic anaemia, autoimmune thrombocytopenia, arthritis, lymphadenopathy, involvement of Waldeyer's ring, hepatosplenomegaly and peripheral eosinophilia. The average age of patients is 60 years. The peripheral blood may show a CLL or plasma cell leukaemia-like appearance. Lymph nodes show a polymorphous infiltrate of lymphocytes, plasmacytoid lymphocytes, plasma cells, immunoblasts and eosinophils. In some cases the appearance resembles CLL. In others, plasma cell predominate, resembling plasma cell myeloma. Rarely, the appearances are those of a nodal large cell lymphoma.
Differential diagnosis
Distinction from marginal zone B-cell lymphoma may be very difficult1. Bone marrow involvemetn and an IgM gammopathy favours lymphoplasmacytic lymphoma2.
Distinction from mantle cell lymphoma may be very difficult.
Small cell lymphocytic lymphoma; may include clonal plasma cells, but not lymphoplasmacytoid cells. Lymphoplasmacytoid lymphoma lacks proliferation centres.
Small cell myeloma; staining for IgM is helpful as less than 1% of myelomas are IgM positive. Myelomas are usually CD20 negative.
Prognosis
The course is typically indolent with a median survival of five years. There may be progression to diffuse large cell lymphoma
References
World Health Organization Classification of Tumours, Tumours of the haematopoietic and lymphoid tissues, IARC Press 2001.
Wotherspoon AC, Hasserjian RP. Immunophenotyping in the differential diagnosis of histologically low grade B cell lymphomas. Current Diagnostic Pathology 2000;6:55-63.
1A clinical evaluation of the International Lymphoma Study Group classification of non-Hodgkin's lymphoma. The Non-Hodgkin's Lymphoma Classification Project. Blood 1997;89(11): 3909-18.
This page last revised 11.9.2003.
©SMUHT/PW Bishop