WALDEYER RING LYMPHOMAS - A CLINICOPATHOLOGICAL STUDY OF 79 CASES

Waldeyer ring lymphomas belong to a category of tumours which has not yet been fully defined. Their relation to mucosa-associated lymphoid t issue (MALT) and other extranodal lymphomas remains largely unknown. W e performed a clinicopathological retrospective study of 79 patients, and compared them with a series of MALT and nodal lymphomas. Tumours f rom the nasopharynx and palatine tonsil showed similar histological pr ofiles, with a predominance of large B-cells. Centroblastic lymphomas constituted the largest group (n=45), followed by those of centrocytic type (9) with smaller groups of centroblastic-centrocytic (5) and Hod gkin's lymphomas (2). Three monocytoid B-cell lymphomas were identifie d. Only one case could be classified as MALT lymphoma. The frequency o f bcl-2 expression in large B-cell tumours of Waldeyer's ring has an i ntermediate range between large B-cell lymphomas occurring in mucosal and nodal locations. Epitheliotropism was present in all low-grade cas es, and was therefore not a useful marker in the identification of pot ential MALT lymphomas in contrast with other mucosal sites. Comparativ e survival studies showed significant overall differences between Wald eyer ring lymphomas, MALT and nodal cases. These disappeared after tak ing stage and histological grade into account. We conclude that Waldey er ring lymphomas show distinctive features, mainly in terms of histol ogical distribution and immunophenotype. The key factor determining th eir behaviour could be their different spreading capability. These fin dings suggest that extranodal lymphomas are heterogeneous, and indicat e the need for additional efforts to clarify this.