Forster S, Sattler H P, Hack M, Romanakis K, Rohde V, Seitz G, Wullich B
Institute of Human Genetics, University of the Saarland, Homburg, Germany.
Surgery. 1998 Jan;123(1):13-8.
Microsatellite instability (MIN) seems to characterize a particular subset of sporadic colorectal adenocarcinomas with the studies indicating a better clinical outcome for patients with MIN-positive tumors than for those with MIN-negative ones. The goal of this study was to further clarify whether a genotype-specific histomorphology of the right-sided colonic carcinomas can be identified.
MIN status, DNA content, and p53 protein expression were evaluated in cryoconserved specimens from 20 adenocarcinomas of the proximal colon and correlated to stage, grade, and other histomorphologic features. The study was restricted to tumors of the proximal colon because approximately 90% of all MIN-positive tumors were found in the proximal colon, and differences between right- and left-sided tumors cannot be excluded a priori.
By using four microsatellite markers, instability was detected in 35% of the tumors analyzed. The clinicopathologic features in the MIN-positive tumors were found to differ markedly from the MIN-negative tumors in their poorly differentiated histologic pattern, extracellular mucin production, and favorable lymph node and distant metastatic behavior. A marked association was found between MIN positivity and DNA diploid status, as well as negative p53 immunostaining.
The MIN-positive colonic carcinomas were characterized by distinct histomorphologic features that are recognizable at routine diagnostic evaluation. Poorly differentiated adenocarcinomas of the proximal colon, with only a few lymph nodes and no distant metastases at presentation, and lack of p53 accumulation are highly suggestive of being MIN positive. These tumors should be discriminated from the other poorly differentiated carcinomas, because they seem to be associated with an improved prognosis compared with the tumors without microsatellite instability.
微卫星不稳定性（MIN）似乎是散发性结直肠癌的一个特殊亚组的特征，研究表明，MIN阳性肿瘤患者的临床结局优于MIN阴性患者。本研究的目的是进一步阐明是否可以识别右侧结肠癌的基因型特异性组织形态学。
对20例近端结肠癌冷冻保存标本的MIN状态、DNA含量和p53蛋白表达进行评估，并与分期、分级和其他组织形态学特征相关联。该研究仅限于近端结肠癌，因为大约90%的MIN阳性肿瘤位于近端结肠，且不能排除左右侧肿瘤之间的差异。
通过使用四个微卫星标记，在35%的分析肿瘤中检测到不稳定性。发现MIN阳性肿瘤的临床病理特征在组织学分化差的模式、细胞外粘蛋白产生以及良好的淋巴结和远处转移行为方面与MIN阴性肿瘤明显不同。发现MIN阳性与DNA二倍体状态以及p53免疫染色阴性之间存在显著关联。
MIN阳性结肠癌具有独特的组织形态学特征，在常规诊断评估中可识别。近端结肠低分化腺癌，就诊时仅有少数淋巴结且无远处转移，且缺乏p53积累，高度提示为MIN阳性。这些肿瘤应与其他低分化癌相鉴别，因为与无微卫星不稳定性的肿瘤相比，它们似乎与预后改善相关。
