Santhanam Divya, Chan Stephanie, Nguyen Chris, Racosta Juan, Xenacostas Anargyros, Robertson Kara, Silverman Michael
Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.
Department of Neurology, Western University, London, Ontario, Canada.
J Assoc Med Microbiol Infect Dis Can. 2024 Mar 29;9(1):52-56. doi: 10.3138/jammi-2023-0021. eCollection 2024 Mar.
Low Count Monoclonal B-Cell Lymphocytosis (LC-MBL) is a relatively poorly understood entity which has been suggested to be very common in asymptomatic adults and possibly related to infectious complications despite not progressing to CLL.
We describe the first case of Progressive Multifocal Leukoencephalopathy (PML) presenting in a 72-year-old man with LC-MBL but no other immunocompromising conditions.
A diagnosis of PML was confirmed with classic MRI findings in association with a high CSF John Cunningham polyomavirus (JCV) viral load (4.09' 10 copies/mL). An extensive search for underlying immunocompromising conditions only demonstrated LC-MBL representing approximately 4% of total leukocytes (0.2' 10/L).
This is the first report of PML in association with LC-MBL. Careful review of peripheral blood flow cytometry results is necessary to identify this disorder. Further study of the epidemiology and infectious complications of LC-MBL are warranted.
低计数单克隆B细胞淋巴细胞增多症（LC-MBL）是一个相对了解较少的实体，据推测在无症状成年人中非常常见，尽管不会进展为慢性淋巴细胞白血病（CLL），但可能与感染并发症有关。
我们描述了首例进展性多灶性白质脑病（PML），发生在一名72岁患有LC-MBL但无其他免疫功能低下情况的男性身上。
通过经典的MRI表现以及高脑脊液约翰·坎宁安多瘤病毒（JCV）病毒载量（4.09×10拷贝/毫升）确诊为PML。对潜在免疫功能低下情况进行的广泛检查仅发现LC-MBL，其占白细胞总数的约4%（0.2×10/L）。
这是首例与LC-MBL相关的PML报告。有必要仔细审查外周血流式细胞术结果以识别这种疾病。对LC-MBL的流行病学和感染并发症进行进一步研究是有必要的。
