Composite monoclonal B‐cell lymphocytosis and MYD88 L265P‐positive lymphoplasmacytic lymphoma in a patient with IgM light chain amyloidosis: Case report
Composite monoclonal B‐cell lymphocytosis and MYD88 L265P‐positive lymphoplasmacytic lymphoma in a patient with IgM light chain amyloidosis: Case report
复制标题
IgM 轻链淀粉样变性患者复合单克隆 B 细胞淋巴细胞增多症和 MYD88 L265P 阳性淋巴浆细胞淋巴瘤：病例报告
DOI：
10.1111/pin.12937
复制
发表时间：
2020
影响因子：
2.2
通讯作者：
Kondo Tetsuo
中科院分区：
文献类型：
--
作者：
Oishi Naoki;Inoue Tomohiro;Odate Toru;Mochizuki Kunio;Ohashi Kenichi;Kirito Keita;Kondo Tetsuo
单克隆B细胞淋巴细胞增多症（MBL）是慢性淋巴细胞淋巴瘤（CLL）样B细胞的早期或前体无症状增生。淋巴浆细胞性淋巴瘤（LPL）是一种以myd88l265p突变为特征的B细胞肿瘤，临床上常伴有Waldenström巨球蛋白血症。在此，我们报告一例IgM轻链（AL）淀粉样变患者出现罕见的复合MBL和LPL。一名已知IgM单克隆蛋白的74岁男性发生蛋白尿。未见淋巴细胞增多。肾活检显示肾小球和血管中有AL λ淀粉样蛋白沉积。随后的骨髓活检显示结节性非典型CLL样小B细胞增生和分散的外周LPL。免疫组织化学和/或流式细胞术显示，非典型CLL样群体表达CD19、CD20、CD5、弱CD23、LEF‐1和表面Igκ减少。LPL表达CD19、CD20和表面Igλ阳性。通过激光捕获显微解剖和等位基因特异性聚合酶链反应，我们证实myd88l265p在LPL中检测到，但在非典型CLL样人群中检测不到。因此，我们证明了这两个群体是克隆独立的，并做出了复合MBL和LPL的诊断。在这种复杂的病例中，综合临床、病理、免疫表型和遗传学评估是必不可少的，特别是“克隆特异性”myd88基因分型可能有助于低级别B细胞淋巴瘤的鉴别诊断。
Monoclonal B‐cell lymphocytosis (MBL) is an early or precursor asymptomatic proliferation of chronic lymphocytic lymphoma (CLL)‐like B‐cells. Lymphoplasmacytic lymphoma (LPL), often clinically associated with Waldenström macroglobulinemia, is a B‐cell neoplasm characterized by frequentMYD88L265P mutation. Here, we report a rare composite MBL and LPL in a patient with IgM light chain (AL) amyloidosis. A 74‐year‐old male with a known IgM monoclonal protein developed proteinuria. No lymphocytosis was detected. Renal biopsy showed deposition of AL λ amyloid in the glomeruli and vessels. Subsequent bone marrow biopsy revealed nodular atypical CLL‐like small B‐cell proliferation and scattered peripheral LPL. Immunohistochemistry and/or flow cytometry revealed that the atypical CLL‐like population expressed CD19, CD20, CD5, weak CD23, LEF‐1 and diminished surface Igκ. The LPL was positive for CD19, CD20 and surface Igλ. Using laser‐capture microdissection and allele‐specific polymerase chain reaction, we confirmed thatMYD88L265P was detectable in the LPL but not in the atypical CLL‐like population. Thus, we demonstrated that these two populations were clonally independent, and made the diagnosis of composite MBL and LPL. An integrated clinical, pathological, immunophenotypic and genetic assessment is essential in such complicated cases, and especially ‘clone‐specific’MYD88genotyping may facilitate the differential diagnoses of low‐grade B‐cell lymphomas.