直肠扁桃体2例临床病理分析

Rectal tonsil:a clinicopathological analysis of 2 cases

目的探讨直肠扁桃体(rectal tonsil,RT)的临床病理特征、诊断与鉴别诊断。方法收集2例RT的临床资料,采用免疫组化检测CK、CD3、CD20、CD21、BCL-2、CD38、CD68、κ、λ、p53及Ki-67的表达,并结合相关文献总结其临床病理特征。结果例1,女性,59岁,因便秘与腹泻交替入院行常规体检并活检。例2,女性,40岁,偶尔出现直肠出血,经标准内镜平台接受内镜黏膜下剥离术切除直肠壁突出的息肉样包块。2例临床均误诊为内痔,经术后病理确诊为RT。肿瘤呈边界清楚的息肉样实体,镜下病变由累及固有层或黏膜下层的离散结节性淋巴样增生性病变组成,轮廓形似小号扁桃体,其固有层可见淋巴滤泡伴密集的成熟性淋巴细胞与反应性浆细胞混合。免疫表型:CD20在生发中心、CD3在滤泡外呈斑驳状阳性;BCL-2除生发中心外呈阳性;κ和λ共阳性表明RT属于多克隆疾病,Ki-67增殖指数较低(1%~3%)。随访4~6个月,均未见复发与转移。结论RT是种少见的直肠良性淋巴增生,应与其他类似病变如派尔斑、淋巴滤泡性直肠炎及淋巴瘤等鉴别,充分认识其临床病理特征有助于确诊。

Purpose To investigate the clinicopathologic features,diagnosis and differential diagnosis of rectal tonsil(RT).Methods The clinical data of 2 cases of RT were collected and expression of CK,CD3,CD20,CD21,BCL-2,CD38,CD68,κ,λ,p53 and Ki-67 were detected by immunohistochistry,and related literatures were reviewed and summarized their clinicopathological characteristics.Results In case one,a 59-year-old female,who complained of constipation alternating with diarrhea,was admitted to the hospital for a routine physical examination and biopsy.Meanwhile,in case two,a 40-year-old woman presented with rectal bleeding occasionally.She was underwent an endoscopic submucosal dissection(ESD)by using standard endoscopy platform for removing a polyp-like neoplasms protruding from the rectal wall.Both patients were clinically misdiagnosed with internal hemorrhoids,which were pathologically confirmed to be RT after surgey.Grossly,the lesions displayed as well-defined polypoid mass.Microscopically,they were composed of discrete nodular lymphoid proliferative lesions involving the lamina propria or submucosa.Panoramic views of the morphology similar to minimal tonsils where follicles surrounded by mature lymphocytes that intermingled with scattered reactive plasma cells.Immunohistochemically,both showed mottled expression of CD20 in germinal centers and CD3 in extrofollicles,respectively.BCL-2 was positive except germinal centers.Co-expression ofκandλindicated that rectal tonsil was a disease of multiclonal.Ki-67 index was low(about 1%-3%).No recurrence or metastasis was found in two cases after a follow-up for 4-6 months.Conclusion RT is a rare benign lymphoid hyperplasia of the rectum.It should be distinguished from other mimics such as Peyer’s patches,lymphoid follicular proctitis,and lymphoma etc.Full recognition of its clinicopathologic characteristics is helpful to render an appropriate diagnosis.