小肠移植中急性抗体介导排斥反应的病理学

Histological alterations in transplanted small bowel after acute antibody-mediated rejection

目的:观察重度急性抗体介导排斥反应(antibody-mediated rejection,AMR)的病理形态学改变,回顾分析相关文献,为小肠移植急性AMR的诊断总结经验.方法:切除的失功能移植肠经10%中性福尔马林固定,石蜡包埋,4?m切片并行HE染色.详细观察移植物中肠壁各层及肠系膜内组织中主要的病理形态学改变,分级评价急性排斥反应及血管病变,并进行C4d免疫组织化学染色.结果:移植物内各级血管广泛受累,包括肠壁及肠系膜内各级血管.受累血管的改变以肠壁浆膜下层内的小血管及动静脉的滋养血管最为显著,主要表现为小血管壁的纤维素性坏死和/或血管内血栓形成,受累血管周围组织中性粒细胞浸润,红细胞漏出,组织水肿,部分病变血管周围伴有纤维素性坏死.免疫组织化学染色可见病变血管内膜C4d沉积.小肠黏膜固有层内血管显著扩张伴淤血,偶见血栓形成,肠黏膜隐窝上皮细胞正常,未见急性排斥反应.结论:血管壁的纤维素性坏死及血管内血栓形成是重度急性AMR的主要病理学改变.病变可以广泛累及移植物内各级血管;小肠黏膜内血管的病变可能不代表最严重的病变;临床早期确诊AMR的发生不能单纯依赖小肠黏膜活检.

AIM： To observe the histopathological changes in transplanted small bowel from a patient developing acute antibody-mediated rejection （AMR） and to perform a literature review. METHODS： The resected allograft was fixed in 10% buffered formalin, embedded in paraffin, sectioned, and stained with hematoxylin and eosin. Morphological changes in the mucosa, intestinal wall and mesentery were observed by two pathologists separately. Acute rejection, vas- cular lesions and related changes were assessed. Immunohistochernical staining of C4d was also performed.RESULTS： AMR lesions were widely distrib- uted in the allograft, involving muscular arter- ies, arterioles, capillaries, vasa vasorum, venules and veins. The most serious AMR was observed in arterioles located in the submucosa and vasa vasorum. Main morphological changes included fibrous necrosis of blood vessel wall, thrombo- sis, and leucocyte margination. Neutrophilic granulocyte infiltration was noted in the edema- tous interstitium surrounding the involved blood vessels, with numerous erythrocytes ex- travasated. The fibrocollagenous network and part of the smooth muscle cells of the outer layer of the muscularis externa showed fibrous necro- sis. Foci of lysis were present in the outer layer of arteries adjacent to the involved vasa vaso- rum. Foci of medial necrosis in the arteries were also observed. Immunohistochemical staining showed C4d deposition in the involved blood vessels. The blood vessels in the lamina propria showed congestion and significant dilation, and thrombosis was occasionally observed. No morphological changes were found in the crypt epithelium. There was no acute rejection in the mucosa. CONCLUSION： Fibrous necrosis of blood ves- sel wall and thrombosis are main morphological changes in the transplanted small bowel after severe AMR. All types of blood vessels in the allograft can be involved, but the lesion in mu- cosal blood vessels may not reflect the most seri- ous injury. Therefore, early diagnosis of AMR can not rely on the biopsy of intestinal mucosa.