Objective: To investigate the pathomorphological characteristics of colorectal adenoma with submucosal pseudoinvasion and to summarize the corresponding pseudoinvasion patterns. Methods: The clinicopathological data of 9 cases of colorectal adenoma were collected at 989 Hospital of PLA Joint Logistics Support Force (4 cases) and Beijing Chaoyang Hospital, Capital Medical University (5 cases), from 2016 to 2019. retrospectively, and the histomorphological characteristics and immunophenotypes were analyzed, and discussed in light of the relevant literature. Results: There were 8 cases of adenoma with stalk. Tumor glands were found in the submucosa at the head end of adenoma, similar to infiltrating adenocarcinoma. The structure and cellular morphology of submucosal glands were very similar to the intramucosal tumor while the local submucosal tumor showed continuity with the intramucosal tumor. The submucosal tumors were lobule-like or nest-like with clear boundary. The outline of the gland was smooth and blunt-round, and there was loose fibromyxoid stroma around the gland, similar to the mucosa propria stroma. Some cases of the submucosal glands were cystic dilated with mucocele formation and hemosiderin deposition. One case with broad stalk-base showed an elevated adenoma with local high grade dysplasia involved in the aggregated lymphoid nodule, forming the lymphoglandular complexes, simulating invasive adenocarcinoma with associated submucosal lymphoid aggregates. Submucosal cancer tissue and intramucosal cancer tissue had continuity, and their morphology was the same. The submucosal tumor was round in the outline, smooth and blunt in the edge, and surrounded by lymphoid tissue. There was no stromal response around the gland to promote the proliferation of connective tissue, neither was there single-cell or small-cell cluster, sharp angle branch of gland, or vascular infiltration. Conclusions: There are two unique morphological patterns in colorectal adenoma with submucosal pseudoinvasion. Morphologically, the data show that one is lobular-like pattern, and the other is lymphoglandular complexes-like pattern. The main features of the two patterns are the same-morphology and continuity of submucosal tumor and intramucosal tumor. The pushed glands were surrounded by the intrinsic membrane stroma and muscularis mucosae in proper order, lacking the typical morphological characteristics of invasive adenocarcinoma.
目的： 探讨结直肠腺瘤伴黏膜下层假性浸润的病理形态学特征，并总结相应的假性浸润模式。 方法： 收集2016—2019年间解放军联勤保障部队第九八九医院病理科4例和首都医科大学附属北京朝阳医院病理科5例结直肠腺瘤伴黏膜下层假性浸润的病例，共计9例，观察其组织形态学特征和免疫表型，并结合文献进行分析。 结果： 结肠有蒂腺瘤8例，黏膜下层可见肿瘤性腺体，类似浸润性腺癌。黏膜下层腺体结构和细胞形态与黏膜内肿瘤相同，局部黏膜下层肿瘤与黏膜内肿瘤有连续性。黏膜下层肿瘤呈推挤式的分叶状或巢团状，腺体轮廓平滑钝圆，腺体周围少量间质组织类似于黏膜固有层间质，部分病例腺体外围黏膜肌错综增生，并常见黏膜肌包绕腺体。有些病例黏膜下层腺体扩张、间质内黏液结节形成及含铁血黄素沉积。1例为发生在直肠的广基隆起型腺瘤伴局部高级别异型增生累及集合淋巴小结形成淋巴腺复合体，并陷入黏膜下层，类似浸润性腺癌周围被淋巴组织包绕。淋巴腺复合体内的肿瘤腺体和黏膜内病变相延续，并且组织学形态相同，肿瘤前缘可见腺体轮廓呈推挤式类圆形，以及不连续的黏膜肌，无典型浸润性腺癌所有伴有的纤维间质反应、肿瘤出芽、腺体锐角分支及脉管浸润等形态特征。 结论： 结直肠腺瘤伴黏膜下层假性浸润可总结为两种独特的形态学模式，模式一为分叶状，缺少淋巴组织反应；模式二为淋巴腺复合体样。两种模式的主要特征为黏膜下层肿瘤和黏膜内肿瘤形态相同，并有连续性，推挤式的腺体周围伴固有膜间质和黏膜肌包绕，并且无典型浸润性腺癌的形态特征。.
Keywords: Adenocarcinoma; Colorectal neoplasms; Compomers; Lymphocytes, tumor-infiltrating; Natural orifice endoscopic surgery.