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Aim: To distinguish between patients with reactive lymphocytosis and those with malignant lymphoid proliferations, with particular reference to hyper-reactive malarial splenomegaly and splenic lymphoma with villous lymphocytes., Patients: Forty-four patients, residents of the Ashanti region of Ghana that is hyperendemic for Plasmodium falciparum malaria, were studied. All patients had splenomegaly greater than 10 cm. They were given proguanil 100 mg/day for a minimum of 6 months. Lymphocyte surface phenotypes were studied on the peripheral blood smears, immunoglobulin gene rearrangement by the Southern blot technique, serum IgM concentration using the Nor-Partigen-IgM kit, and serum paraprotein concentration by electrophoresis., Results: Based on the response to proguanil, the patients were categorized into good respondents, partial respondents, and non respondents. Peripheral blood lymphocytes exceeded 30% in 19, and villous lymphocytes were less than 30% in 25 patients., Conclusion: Splenic lymphoma with villous lymphocytes may be difficult to differentiate from the African variant of chronic lymphocytic leukemia which is associated with splenomegaly and from hyperreactive malarial splenomegaly with lymphocytosis. In West Africa, a peripheral blood lymphocyte count greater than 10 x 109/L, with more than 30% of villous lymphocytes and failure of splenic regression with anti-malarial therapy suggest a diagnosis of splenic lymphoma with villous lymphocytes.

Hyperreactive malarial splenomegaly (HMS) is found in geographical association with B cell lymphoproliferative disorders such as 'African' chronic lymphocytic leukaemia (CLL) and splenic lymphoma with villous lymphocytes (SLVL). It is sometimes not easy to make a differential clinical diagnosis between these conditions. We have previously used Southern blotting as a definitive method for the diagnosis of monoclonal lymphoproliferation in these disorders, but this is expensive, lengthy and technically difficult. In the present paper we have compared Southern blotting with polymerase chain reaction (PCR) amplification of the immunoglobulin heavy chain gene. We found an excellent correlation between the 2 methods in demonstrating monoclonal populations of lymphocytes in patients with a clinical diagnosis of CLL or SLVL. We have further demonstrated monoclonality in a patient who could not be classified as CLL or SLVL on clinical criteria alone. In contrast, patients with well defined HMS or with non-B cell proliferations all showed polyclonal rearrangements. We propose that the immunoglobulin gene PCR is a useful tool for the investigation of tropical splenomegaly of uncertain origin.

Splenic lymphoma with villous lymphocytes (SLVL) is a monoclonal B-lymphoproliferative disorder characterised by splenomegaly and distinctive villous lymphocytes in the peripheral blood. It has not previously been reported from Africa, but we describe ten Ghanaian patients with SLVL seen at one hospital during a 4-year period. The clinical presentation is similar in Africa and in temperate regions, though the lymphocyte count is higher in African patients and the disorder predominantly affects middle-aged women rather than elderly men. It is likely that SLVL has previously been classified as splenic chronic lymphocytic leukaemia or hyper-reactive malarial splenomegaly.