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A total of 417 evaluable patients with non-Hodgkin's lymphomas were diagnosed between January 1974 and December 1983 at the American University of Beirut Medical Center in Beirut, Lebanon. Of these, 179 (43%) patients had nodal lymphomas, and 183 (44%) had extranodal lymphomas. The commonest lymphoma was diffuse large cell (27%), followed by large cell immunoblastic (21%). The histopathologic pattern was follicular in 18% of the nodal lymphomas and in 5.3% of the extranodal forms. The most common site of extranodal lymphoma was the gastrointestinal tract (46.5%), followed by Waldeyer's ring (19%). Small intestinal lymphomas were three times more common than gastric lymphomas. Immunoproliferative small intestinal disease (IPSID) was diagnosed in 20 of 59 patients who had primary small intestinal lymphoma. Of the 34 patients who had Waldeyer's ring lymphoma, 7 had gastrointestinal involvement at some time during the course of the disease. Nodal lymphomas were associated with poor prognostic factors: 82% were diffuse; 77% had advanced disease at presentation; 77% had intermediate- or high-grade malignancy lymphoma; 40% had marrow involvement; and 46% had B symptoms. In children, the most common lymphoma was Burkitt's, and 80% of pediatric lymphomas were high-grade malignancy. In conclusion, this study delineates the special features of non-Hodgkin's lymphomas in the Middle East: The presence of IPSID; the high incidence of extranodal forms, in particular the intestinal ones; and the rarity of follicular lymphomas.

Seventy-five cases of primary small intestinal lymphoma (PSIL) were diagnosed in adults at the American University of Beirut Medical Center (AUBMC) during the period from 1961 to 1980. Two additional cases of immunoproliferative small intestinal disease (IPSID) in the premalignant phase also were studied. Thirty-two patients had IPSID; 27 non-IPSID; and in 18 patients it was difficult to distinguish IPSID from non-IPSID. While the former was shown to be a distinct disease entity with characteristic clinical, pathologic, and immunologic features, the latter was found to have no particular features in this part of the world. In addition to alpha heavy chain protein (AHCP) which is the biological marker of IPSID, the most important finding that distinguished the two diseases was that IPSID was always associated with a dense, compact mucosal cellular infiltrate (MCI) that was continuous and uninterrupted all along the length of the small intestine. In non-IPSID, MCI was lacking and the pathology was confined to sites of gross abnormalities. Sites distant to the primary lesion were free of disease. It was reported previously that the MCI in IPSID is characteristically diffuse plasmacytic or lymphoplasmacytic (DLP). Our study indicates that in addition to this infiltrate, the disease may be associated with another type of infiltrate which is follicular lymphoid (FL). Sixteen patients had DLP; ten, FL; and three, mixed infiltrate. The relationship of AHC disease and IPSID is discussed. AHCP may be found in intestinal fluid, serum, within the abnormal cell, or at its surface. Immunofluorescence and immunoperoxidase studies must be done on all intestinal and nodal tissue specimens in all patients with PSIL for the detection of AHCP, particularly in those where serum and intestinal fluid are negative for this protein. The hypothesis that the DLP infiltrate represents the secretory form of IPSID, while the FL the nonsecretory form, is introduced. IPSID is an ideal model for the study of the etiology and pathogenesis of lymphoma in man.