[Nodal lymphoplasmacytic lymphoma/Waldenstrom's macroglobulinemia: a clinicopathological and prognostical study]

Objective: To study the clinicopathological features and prognosis of nodal lymphoplasmacytic lymphoma/Waldenstrom's macroglobulinemia (n-LPL/WM). Methods: A total of 19 cases of n-LPL/WM were collected from May 2009 to January 2020 at First Affiliated Hospital of Zhengzhou University. The clinicopathologic features, immunophenotype, Ig gene rearrangement (BIOMED-2), MYD88 L265P mutation status (by Sanger sequencing) and follow-up data (by telephone) were analyzed. Results: There were 15 males and 4 females with a median age of 61 years (range 43 to 82 years). There were 14 WM and five LPL. The most common symptoms were weakness, fatigue (9/19) and B symptoms (11/19). Majority of the patients (16/18) presented with systemic multiple lymphadenopathies. Eighteen patients presented at advanced stages (Ⅲ/Ⅳ stage). Serum M protein status was IgM (15 cases), IgG (1 case), IgA (1 case) and no-secretory type (2 cases). Seventeen patients had bone marrow involvement. Morphologically, all 19 cases were divided into two groups: typical group (9 cases) or atypical group (10 cases). In the typical group, the structures of the lymph nodes were preserved; the neoplastic cells were predominantly plasmacytoid lymphocytes or mixed small lymphocytes, plasmacytoid lymphocytes and plasma cells, without proliferation of FDC network and follicular implantation. In the atypical group, the tumor showed effaced nodal architecture (5 cases), mainly proliferation of small lymphocytes (6 cases), FDC proliferation and/or follicular implantation (6 cases), marginal zone B cell differentiation (4 cases) and diffuse amyloidosis (1 case). Hemosiderin deposition (19 cases), infiltration of fatty tissue (19 cases) and interstitial sclerosis (9 cases) were commonly seen in both groups. Immunohistochemically, the neoplastic B cells expressed CD20 and CD79α, and the neoplastic plasma cells were positive for CD38, CD138 and MUM-1; eight cases showed light chain restriction; of the seven detected cases, five expressed IgM and the other two expressed IgG and IgA respectively; four cases expressed CD23 weakly, Ki-67 index was 10%-30%. MYD88 L265P mutation was seen in 18/18 cases. There was no significant difference in clinicopathologic features and prognosis between the two groups (P>0.05). The median follow-up time was 61 months, 11 patients were alive, while eight died; the 5-year survival rate was 21.1%. Conclusions: n-LPL/WM is rare, but patients usually present in advanced stages. It is easily confused with other small B-cell lymphomas with plasma cell differentiation, especially basing on morphologic features alone; thus the accurate diagnosis of n-LPL/WM requires a combination of clinical features, serum M protein, immunohistochemistry, bone marrow morphology,flow cytometry and MYD88 L265P mutation status etc. The prognosis of n-LPL/WM may be not very good, and further studies with more cases are needed.