Fine‐needle aspiration biopsy findings in marginal zone B cell lymphoma

Marginal zone B cell lymphomas (MZBCLs) represent a category of non‐Hodgkin's lymphoma which may arise in a wide variety of extranodal organs where they are termed low grade B cell lymphomas of mucosa‐associated lymphoid tissue (MALT). MZBCLs may involve primarily lymph nodes and or spleen where they are designated monocytoid B cell lymphoma or splenic marginal zone lymphoma, respectively. Recognition of this category of lymphoma, in particular, extranodal MALT lymphoma, is clinically significant in determining optimal therapy. Although there have been recent case reports describing the cytologic findings in low grade MALT lymphoma in various extranodal organs, this category of lymphoma has not been widely recognized or discussed in the cytology literature. The cytologic findings in seven fine‐needle aspirations and two bronchial washings of histologically confirmed marginal zone lymphoma (five extranodal MALT lymphomas and four nodal marginal zone lymphomas) are described. In all of the cases, the cytologic specimens showed a polymorphous proliferation comprising a predominant population of intermediate sized lymphoid cells with centrocyte‐like or monocytoid features, transformed cells, and variable numbers of plasma cells. These findings, while highly suggestive of MALT lymphoma in extranodal proliferations, may be more difficult to distinguish from reactive conditions in lymph nodes. Diagn. Cytopathol. 1999;20:190–198. © 1999 Wiley‐Liss, Inc.