低位直肠癌直肠系膜区域微转移的病理形态学观察

目的 研究低位直肠癌在直肠系膜各区域微转移的分布规律,为直肠癌最佳手术方案的制定提供病理学依据。方法62例经低前切除和全直肠系膜切除术的患者,其手术标本经取材、包埋后,以2．5mm的间隔行大组织切片,切片行HE染色。在大组织切片上直肠系膜被分为3个区域：直肠系膜外侧区、直肠系膜中间区、直肠系膜内侧区。通过显微镜在切片上观察直肠癌微转移灶的区域分布、发生频率、类型、是否淋巴转移以及与肿瘤原发灶的关系。结果直肠癌微转移灶发生在直肠系膜和直肠系膜外侧区的频率分别为38．7％（24／62）和25．8％（16／62）。微转移灶侵犯标本环周切缘和远端直肠系膜的频率均为6．5％（4／62）,远端直肠系膜的转移不超过肿瘤下缘以远3cm。大多数直肠系膜内有微转移的患者（20／24）,其临床病理分期为Dukes C。结论低位直肠癌手术时,完整地切除直肠系膜而不破坏其外侧区至关重要;本研究的结果支持远端直肠系膜的切除长度不能〈4cm的临床原则。

Distribution of micrometastatic nodules of low rectal cancer in mesorectum: a pathological study using whole-mount sections

OBJECTIVE: To investigate the regional spread of micrometastatic nodules in the mesorectum from low rectal cancer, and provide further pathological evidence to optimize radical resection procedure for rectal cancer. METHODS: A total of 62 patients with low rectal cancer underwent low anterior resection and total mesorectal excision (TME) was included in this study. Surgical specimens were sliced transversely and serial embedded blocks were made at 2.5 mm interval, and paraffin sections were stained with hematoxylin and eosin. The mesorectum on whole-mount sections was divided into three regions: outer region of mesorectum (ORM), middle region of mesorectum (MRM) and inner region of mesorectum (IRM). Microscopic spread were examined microscopically on the sections for the distribution in different mesorectal regions, frequency, types, involvement of lymphatic system and correlation with the primary tumor. RESULTS: Microscopic spread of the tumor in mesorectum and ORM was observed in 38.7% (24/62) and 25.8% (16/62) of the patients, respectively. Circumferential resection margin (CRM) involved by microscopic tumor foci occurred in 6.5% (4/62) of the patients, and distal mesorectum (DMR) involvement was recorded in 6.5% (4/62) with a spread extent within 3 cm of distal border of the main lesions. Most (20/24) of the patients with microscopic spread in mesorectum were in TNM stage III. CONCLUSION: Results of the present study support that complete excision of mesorectum without destruction of the ORM is essential for surgical management of low rectal cancer, and an optimal DMR clearance resection margin should not be less than 4 cm.