Estimation of silver-binding nucleolar organizer regions (AgNORs) in lymphoproliferative disorders of gastrointestinal tract.

We quantified nucleolar organizer regions demonstrable by silver staining technique (AgNORs) in six cases of reactive lymphoid hyperplasia (RLH), and in 14 low-grade B-cell lymphomas (mucosa-associated lymphoid tissue (MALT) 5, centrocytic 3, centroblastic-centrocytic 6) and 49 high-grade B-cell lymphomas (centroblastic 44, immunoblastic 3, Burkitt's one, large cell anaplastic one). The pooled mean AgNOR number in low-grade B-cell lymphomas was significantly higher than that in RLH, and significantly lower than that in high-grade B-cell lymphomas. There was a statistically significant difference between RLH versus centroblastic-centrocytic lymphoma in pooled mean AgNOR number and in RLH versus centrocytic lymphoma but not in RLH versus MALT lymphoma. The AgNOR numbers in the cellular components of RLH were also analyzed. The follicle center centroblasts of RLH exhibited a significantly higher pooled mean AgNOR number than other kinds of lymphoid cells in RLH. Furthermore, AgNOR numbers of gastrointestinal lymphomas were compared with those of cellular elements in RLH. There was a statistically significant increased AgNOR number of centroblastic lymphoma when compared with neoplastic centroblasts in centroblastic-centrocytic lymphoma and follicular centroblasts in RLH. By contrast, there was no significant difference in AgNOR numbers between MALT lymphomas and interfollicular lymphocytes, mantle zone lymphocytes or follicular centrocytes in RLH, respectively. This study demonstrated a similar increase when non-Hodgkin's B-cell lymphomas in gastrointestinal tract were compared with histogenetically related cellular elements of RLH. AgNOR counting might be useful adjunct in the classification and grading of lymphoproliferative disorders in gastrointestinal tract.