Diagnostic classification and detection of minimal residual disease (MRD) in canine lymphoma

To (i) examine the histopathology and immunophenotype of canine lymphoma according to the NCI Working Formulation and updated Kiel classification adapted to the canine species, (ii) detect clonal rearrangements of antigen receptor genes by PCR assay, (iii) detect Minimal Residual Disease (MRD) in clinical complete remission of chemotherapeutic treated dogs. Fifty formalin-fixed paraffin-embedded tissue from dogs suffering from lymphoma were retrospectively studied. Histopathological results revealed the most common subtype classified by the NCI system was intermediate grade diffuse large cell type (32%) while by the updated Kiel was centroblastic lymphoma(24%).The immunophenotypic study displayed 40% T-subtype (CD3 expression) and 60% B cell (IgM expression) lymphoma. For the PCR assays determining clonality for antigen receptor rearrangement genes and MRD from cytologic and peripheral blood samples of 14 dogs with lymphoma either before chemotherapy and during remission, clonality was detected in 13 of the lymphomas before treatment. MRD was demonstrated in 7 dogs with lymphoma during remission. Detection of MRD during remission in canine lymphoma using PCR technique is considered as an useful tool for prognosis and monitoring relapsing disease.本研究旨在（i）依据适配犬类的美国国家癌症研究所（NCI）工作分类法与更新后的Kiel分类法，分析犬淋巴瘤的组织病理学特征及免疫表型；（ii）通过聚合酶链反应（PCR）检测抗原受体基因的克隆重排情况；（iii）在接受化疗并达到临床完全缓解的淋巴瘤患犬体内检测微小残留病（MRD）。本研究回顾性分析了50份来自淋巴瘤患犬的福尔马林固定石蜡包埋（FFPE）组织样本。组织病理学结果显示，按NCI系统分类最常见的亚型为中级弥漫大细胞型（占比32%），而按更新后的Kiel分类则为中心母细胞淋巴瘤（占比24%）。免疫表型分析结果表明，40%的淋巴瘤为T细胞亚型（表达CD3），60%为B细胞淋巴瘤（表达IgM）。针对14只淋巴瘤患犬在化疗前及缓解期的细胞学样本与外周血样本，开展抗原受体重排基因克隆性及MRD检测，结果显示治疗前有13例淋巴瘤样本检出克隆性重排；缓解期的7只患犬体内检出MRD。利用PCR技术在淋巴瘤患犬的缓解期检测MRD，可作为预后评估与复发监测的有效工具。