Usefulness and Limitations of Current Diagnostic Strategies for Pulmonary Mucosa-Associated Lymphoid Tissue Lymphoma: Lessons Learned From a Large Cohort

Context.--The pathologic diagnosis of pulmonary extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) is challenging. Objective.--To evaluate the diagnostic usefulness and limitations of current diagnostic strategies for pulmonary MALT lymphoma. Design.--A retrospective review of 120 cases of pulmonary MALT lymphoma from 2014 through 2021 was performed. Results.--Clinicoradiologic presentations overlapped with previous observations in patients with MALT lymphoma, such as a wide age range, female predominance, frequent association with autoimmune disease or immunodeficiency, and broad imaging findings. The histopathologic diagnosis was based on a combination of morphology, immunohistochemistry, and demonstration of B-cell lineage clonality. Two-thirds (76 of 113) of MALT lymphomas had lympho-plasmacytoid cytomorphology. Occasionally, MALT lymphomas were associated with granulomas/giant cells (29%, 35 of 120) or immunoglobulin deposition disease (21%, 25 of 120), including light chain/heavy chain deposition disease, amyloidosis, and/or crystal storing histiocytosis. While CD5, CD10, Bcl-2, and Bcl-6 rarely revealed aberrancies, aberrant CD43 expression either on B-cells or on plasma cells was detected in 42% (27 of 64) of cases, including cases for which proof of clonality could not be obtained. [kappa]/[lambda] in situ hybridization was particularly useful for tumors with lymphoplasmacytoid morphology but performed poorly in lymphomas having no plasmacytic differentiation. [kappa]/[lambda] immunohistochemistry showed no additional usefulness when applied together with [kappa]/[lambda] in situ hybridization. Immunoglobulin gene rearrangement studies by polymerase chain reaction achieved high detection rates of clonality in all cytomorphologic subgroups. Conclusions.--Our study offers a practical evaluation of common diagnostic tests in pulmonary MALT lymphoma. We offer recommendations for a diagnostic workup that takes into consideration the usefulness and the specific limitations of the various diagnostic strategies. doi: 10.5858/arpa.2022-0521-OA
Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) represents the most common type of primary lymphoma of the lung. As at other anatomic sites, MALT lymphoma of the [...]