Objective: To study the clinicopathologic features and the key points of differential diagnosis of appendiceal diverticulosis (AD) and low-grade mucinous neoplasm (LAMN) to avoid over-diagnosis. Methods: The clinical data, pathologic features and follow-up information of 20 patients with AD, who were diagnosed in the Peking University Third Hospital from January 2010 to November 2019 were collected and compared with 44 cases of LAMN which were diagnosed during the same period. Results: Among the 20 cases of AD, hypermucinous epithelium, filiform villi or undulating epithelium and mucosa atrophy were observed in 10 (50.0%), 4 (20.0%) and 14 (70.0%) cases, respectively, however, focally loss of lamina propria and mucosa/submucosa fibrosis were observed only in 1 (5.0%) and 4 (20.0%) cases, respectively. Extramural mucin deposits were seen in 11 (55.0%) cases, all were acellular mucin. Mucosal Schwann cell hyperplasia were present in 12 (60.0%) cases. Nine (45.0%) and 5 (25.0%) cases were associated with acute diverticulitis or acute suppurative appendicitis, respectively. In comparison with AD, LAMN cases more frequently showed hypermucinous epithelium (42/44, 95.5%), filiform villi or undulating epithelium (43/44, 97.7%), loss of lamina propria (43/44, 97.7%) and fibrosis and hyalinization of appendiceal wall (44/44, 100.0%), whereas mucosal atrophy (4/44, 9.1%) and Schwann cell hyperplasia(11/44, 25.0%) were less frequently seen (P<0.05). Follow-up information was available for 10 AD patients and 27 LAMN patients; all were alive without evidence of recurrence. Conclusions: Epithelial hyperplasia, loss of lamina propria, fibrosis of the appendiceal wall and extramural mucin deposits may occur focally in AD and should be distinguished from LAMN. The preservation of normal appendiceal mucosa architecture, lack of diffuse appendiceal wall fibrosis and hyalinization, and no definite neoplastic epithelium are the key point for preventing over-diagnosis.
目的： 探讨阑尾憩室病与低级别黏液性肿瘤（LAMN）的临床病理学特征和鉴别诊断要点，避免误诊。 方法： 收集2010年1月至2019年11月北京大学第三医院手术切除的20例阑尾憩室病患者的临床影像及病理学资料，与同期诊断的44例LAMN进行比较，并进行随访。 结果： 20例阑尾憩室病患者中，上皮黏液分泌旺盛10例（50.0%），纤细绒毛状或波浪状上皮4例（20.0%），黏膜萎缩14例（70.0%），仅1例局灶固有层缺失（5.0%），4例局灶黏膜肌/黏膜下层纤维化（20.0%）；11例伴阑尾壁外黏液（55.0%），但黏液池内均未见上皮；12例伴黏膜施万细胞增生（60.0%），9例合并急性憩室炎（45.0%），5例合并急性蜂窝织炎性阑尾炎（25.0%）。LAMN组中，上皮黏液分泌旺盛（42/44，95.5%）、纤细的绒毛或波浪状上皮（43/44，97.7%）、固有层缺失（43/44，97.7%）和阑尾壁纤维化/玻璃样变（44/44，100.0%）的发生率均高于阑尾憩室病组，而黏膜萎缩（4/44，9.1%）和固有层施万细胞增生（11/44，25.0%）的发生率显著低于阑尾憩室病组，差异具有统计学意义（P<0.05）。憩室病组10例获得随访信息，LAMN组27例获得随访信息，两组获得随访信息的患者均无病生存。 结论： 阑尾憩室病可出现局灶黏膜上皮增生、固有层消失、阑尾壁纤维化和壁外黏液，需要与LAMN鉴别，注意阑尾憩室病黏膜正常结构保留，缺乏真正的肿瘤性上皮和广泛的阑尾壁纤维化、玻璃样变有助于避免过度诊断。.
Keywords: Appendix; Diagnosis, differential; Diverticulum; Neoplasms, cystic, mucinous, and serous.