Clinicopathology of non-neoplastic and neoplastic lymph node swelling

Lymph node swelling, which can be problematic when attempting differential diagnosis between non-neoplastic or neoplastic types, can be grouped into three categories. The first is lymph node swelling due to heterotopia, hamartoma or hyperplasia, the second is due to non-neoplastic lymphoid cell and/or histiocyte proliferation with the appearance of neoplastic proliferation and the third is due to true neoplastic proliferation, but apparently simulating a non-neoplastic condition. The present paper describes some of the clinicopathological features of representative diseases or cases in each category, e.g. Castleman's disease, necrotizing lymphadenitis, "IBL"-like T-cell lymphoma, and lymphoma showing an unusual course initially simulating a non-neoplastic process and then gradually disclosing its neoplastic nature in the late stage. These cases emphasize the importance of close collaboration between the clinician and pathologist together with immunohistochemical studies of lymph node pathology.