Fine-Needle Aspiration Cytology of the Nodal Marginal Zone Lymphoma

ABSTRACT

BACKGROUND: Nodal marginal zone lymphoma (NMZL) is a rare B-cell neoplasm consisting of heterogeneous cellular components and residual B-cell follicles. Because of such histological features, it is difficult to diagnose NMZL by fine needle aspiration (FNA) cytology. We reviewed FNA cytology of NMZL to identify a cytological clue to avoid misdiagnosing NMZL. METHODS: Histological, cytological, and clinical findings of seven cases of NMZL were reviewed. RESULTS: Most cases showed nodular aggregates of lymphohistiocytes derived from the germinal center irrespective of histological pattern. The cellular components were heterogeneous and composed of mature small lymphocytes, intermediate and large lymphocytes, immunoblasts, tingible body macrophages, and follicular dendritic cells. Intermediate-sized neoplastic cells with a pale nucleus were observed but difficult to identify because of admixed non-neoplastic cells, which outnumbered neoplastic cells. Except for one case with a high proportion of intermediate-sized cells, the other six cases were initially diagnosed as reactive hyperplasia. A flow cytometric analysis was performed in two cases and failed to demonstrate a monoclonal B-cell population. CONCLUSIONS: The FNA showing a reactive hyperplasia-like smear pattern should be carefully observed by experienced cytopathologists to identify intermediate-sized neoplastic cells. Clinical information including the size of the lymph nodes is important to avoid a misdiagnosis.