RUPTURED SPLEENS WITH EXPANDED MARGINAL ZONES DO NOT REVEAL OCCULT B-CELL CLONES

An indolent variant of splenic marginal zone lymphoma (SMZL) lacking m assive splenomegaly has been described as an incidental finding in spl eens removed for rupture or hypersplenism, We studied traumatically ru ptured spleens with expanded margind zones (MZs) to assess the inciden ce of occult monoclonal B-cell populations in this setting, Ninety-one ruptured or lacerated spleens removed from 1984 to 1995 were classifi ed as to whether they had expanded MZs (> 12 cell layers thick), When available, paraffin-embedded, formalin-fixed tissue from cases with ex panded MZs was examined for immunoglobulin heavy chain gene rearrangem ent by polymerase chain reaction (PCR) and stained for CD20, CD43, and kappa and lambda Light chains, Splenectomies were performed for blunt (70 patients) and penetrating (7 patients) trauma, surgical misadvent ure (13 patients), or spontaneous rupture (1 patient). There were 58 m en and 33 women in our study, ranging in age from 17 to 87 years (mean , 40 yr), Average spleen weight was 183 g (range, 44-505 g). Twenty-se ven (30%) of 91 patients had expanded MZs, There were no significant d ifferences in age, sex, spleen weight, or reason for excision between those cases with and without MZ expansion, Germinal centers varied fro m absent to inactive to floridly reactive, Paraffin blocks were availa ble in 24 cases; the 20 with amplifiable DNA were polyclonal by PCR, F ollow-up was available for 25 of the 27 patients with expanded MZs (ra nge, 1-85 mo; medial, 6 mo); lymphoma did not develop in anyone, altho ugh one patient's spleen was morphologically suspicious for lymphoma, showing involvement of red pulp by MZ-type B-cells; PCR revealed a pol yclonal pattern, This patient's 3-year follow-up revealed no evidence of lymphoma Traumatically ruptured spleens with expanded MZs do not se em to harbor occult B-cell clones, as detected by PCR, Although a few cases of incidentally removed spleens have been reported to contain lo w-stage SMZL, this seems to be an infrequent event.