Pb2338: bone marrow involvement in korean patients with lymphomas: a 21-year large single-center study

Topic: 20. Lymphoma Biology & Translational Research Background: The distribution of lymphoma subtypes and their bone marrow (BM) involvement rate have not been reported in Korean ethnicity. Aims: We performed a large single-center study for the comprehensive epidemiology of lymphomas in Korean patients including BM involvement for the first time. Methods: A retrospective review of medical records was performed for 75,005 BM examinations of 26,664 consecutive patients at Asan Medical Center from 2000 to 2020. Results: A total of 7,599 patients (4,391 men and 3,208 women) underwent BM examinations for lymphoma staging: B-lymphomas, 5,967 (78.5%); T- or NK-lymphomas, 1,106 (14.6%); Hodgkin’s disease (HD), 464 (6.1%); post-transplant lymphoproliferative disease (PTLD), 13 [0.2%], and other unspecified lymphomas, 49 (0.6%). The compound annual growth rate (CAGR) was 13.2% for B-lymphomas, 4.7% for T- or NK-lymphomas, and HD 5.2% until 2017, but -16.0% from 2017 to 2019. The ratio of B-lymphoma to T- or NK-lymphoma ratio was 2.0:1 in those < 30 years but 6.1:1 ≥ 30 years (P-value<0.001). BM involvement was observed in 1,341 (22.5%), 250 (22.6%), 46 (9.9%), and 1 (7.7%) among those with B-lymphomas, T- or NK-lymphomas, HD, and PTLD, respectively. The distribution was not significantly differed in men and women. Men showed a significantly higher BM involvement rate than women in B-lymphomas and HD (38.1% vs. 61.9%; 17.4% vs. 82.6%, respectively; all P-values <0.001). Frequently requested B-lymphomas and their BM involvement at the initial referral were as follows (requests/BM involvement): diffuse large B-cell lymphoma (DLBCL), 51.59%/18.76%; mucosa-associated lymphoid tissue lymphoma, 23.54%/9.72%; follicular lymphoma (FL), 8.00%/41.14%; chronic lymphocytic leukemia and small lymphocytic lymphoma (CLL/SLL), 5.12%/94.47%; mantle cell lymphoma (MCL), 3.14%/64.58%; nodal marginal zone lymphoma, 2.62%/21.67%; and Burkitt lymphoma, 2.62%/50.83%. Other B-lineage lymphomas with less frequent requests but high rates of BM involvement included (requests/BM involvement): splenic marginal zone lymphoma, 0.37%/94.12%; lymphoplasmacytic lymphoma, including Waldenstrom’s macroglobulinemia, 0.94%/88.37%; and intravascular diffuse large B-cell lymphoma, 0.22%/80.00%. FL had the highest CAGR (10.8%) among B-lymphomas, followed by MCL (10.4%), DLBCL (5.2%), and CLL/SLL (4.5%). Frequently requested T- or NK-lymphomas and their BM involvement at the initial referral were as follows (requests/BM involvement): NK/T-cell lymphoma, 29.55%/15.52%; peripheral T-cell lymphoma, 25.61%/34.33%; anaplastic large T-cell lymphoma, 17.71%/20.86%; angioimmunoblastic T-cell lymphoma, 10.45%/59.76%; and T-lymphoblastic lymphoma, 8.15%/40.63%. Moreover, two patients with adult T-cell lymphoma/leukemia and one each with intestinal T-cell lymphoma, T-large granular lymphocytic leukemia, and T-prolymphocytic leukemia were requested; all showed 100% BM involvement. Antecedent myeloid malignancies existed in 14 patients (11 with B-lymphomas and 3 with T- or NK-lymphomas), including 3 with acute myeloid leukemia (AML), 9 with myeloid dysplastic syndromes (MDS), and 2 with myeloid proliferative neoplasm. BM involvement was observed in 1 with antecedent AML and 3 with MDS. Summary/Conclusion: Common subtypes showed similar frequencies of BM involvement as those reported in Western studies. The high annual growth rates of FL and MCL were notable. BM involvement was frequent in rare subtypes. Rare cases of lymphomas proceeded by myeloid malignancies or by different types of lymphomas were observed.