[Clinicopathological features and BRAF V600E and MYD88 L265P mutation status of nodal marginal zone lymphoma]

Objective: To investigate the clinicopathological features as well as BRAF V600E and MYD88 L265P mutation status of nodal marginal zone B cell lymphoma (NMZL). Methods: Thirty-two cases of NMZL were diagnosed from September 2009 to February 2021 at the Henan Provincial People's Hospital and Peking University School of Basic Medical Sciences. The clinicopathologic characteristics were obtained and analyzed. BRAF V600E and MYD88 L265P mutation status were identified using PCR and Sanger sequencing, respectively. Results: There were 20 males and 12 females patients with a median age of 69 years (ranging 36-82 years). The most prevalent clinical manifestation was multiple lymph nodes enlargement in head and neck (22/32, 68.8%), followed by inguinal (12/32, 37.5%), axillary (11/32, 34.4%), mediastinum (5/32, 15.6%) and retroperitoneal lymph nodes (4/32, 12.5%). Most of the patients were in Ann Arbor stage Ⅰ/Ⅱ (21 cases). The morphologic features included diffuse (24/32, 75.0%), nodular (5/32, 15.6%), interfollicular (2/32,6.3%) and perifollicular (1/32,3.1%) types. The tumor cells showed monocyte-like, centrocyte-like, small lymphocyte-like and plasma cell-like differentiation. Immunophenotyping revealed diffuse expression of CD20 in all tumor cells, whereas CD43 (11/32, 34.4%), bcl-2 (20/32, 62.5%), MNDA (13/32, 40.6%) and CD5 (2/32, 6.3%) were partially expressed. Ki-67 proliferation index varied from 10% to 40%. BRAF V600E mutation was found in two cases (2/32, 6.3%), but MYD88 L265P mutation was not detected. Eighteen patients survived and three died at the end of follow-up period which ranged 6 to 110 months. Conclusions: The morphologic features of NMZL varies across individuals, it should be differentiated from various B-cell lymphomas; however immunological biomarkers with high specificity for NMZL are still lacking. No MYD88 L265P mutation is found in NMZL. Some cases may harbor BRAF V600E mutation and yet the prevalence remains indeterminate; further researches are warranted.