Splenic lymphoma with villous lymphocytes is a rare type of lymphoma that involves mature B cells. Older names include lymphoma simulating hairy cell leukemia and lymphoplasmacytic lymphoma with circulating villous lymphocytes. Whether this condition is identical to splenic marginal zone lymphoma, or only highly similar, is a matter of debate.
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Splenic lymphoma with villous lymphocytes Wikipedia(Text) CC BY-SA