PRIMARY SPLENIC LYMPHOMA - DOES IT EXIST

The number of primary splenic lymphomas being reported is increasing d espite the rarity of this malignancy, but what really constitutes a ly mphoma arising primarily in the spleen is still a matter of discussion . The authors choose the ''restrictive'' definition of a lymphoma invo lving the spleen and the splenic hilar lymph nodes only. In this way, the risk of epidemiologic or clinical overestimation is avoided. The c linical features of this condition are characterized by non specific s ymptoms and signs, while the prevailing histology is that of a low-gra de or intermediate-type lymphoma. Disease spreading outside of the spl een and its hilar lymph nodes is the single most important factor asso ciated with an unfavorable prognosis. From this usual clinical picture , two distinct nosologic entities can be outlined on the basis of hist ologic and immunologic peculiarities: splenic lymphoma with circulatin g villous lymphocytes and marginal-zone splenic lymphoma. The former a rises from follicular center cells and is characterized by hyperspleni sm, variable percentages of circulating villous lymphocytes and, frequ ently, a monoclonal gammopathy. The latter originates from a peculiar splenic B-cell structure separated by the mantle zone. The proliferati ng cells are medium-sized KiB3-positive lymphocytes with round or clea ved nuclei and pale cytoplasm, which surround follicular centers and i nfiltrate the mantle zone. It is interesting that marginal-zone lympho ma cells share some of the characteristics of the lymphocytes involved in both lymphomas of mucosa-associated lymphoid tissue and the B-mono cytoid lymphomas. Splenectomy is still the most effective therapy for all primary splenic lymphomas.