Primary splenic lymphoma.

Although a number of lymphomas and leukaemias can involve the spleen and may present clinically with splenomegaly, only the B cell disorders SMZL and hepatosplenic gamma/delta T cell lymphoma can be considered true primary splenic lymphomas. The former is not uncommon and has histological features which may be to a certain extent recapitulated by other B cell lymphomas when they involve the spleen. In view of the characteristic clinically indolent behaviour of SMZL and its favourable response to splenectomy, rather than chemotherapy, the differential diagnosis from other B cell lymphomas is important. Hepatosplenic gamma/delta T cell lymphoma is rare; for the purpose of precise classification, it needs to be distinguished from other NK like T cell lymphomas and NK cells lymphomas that sometimes involve the spleen.