Histologic diagnosis
Case 209
【Progress】
Colon endoscopy showed advanced cancer (Borrmann III type). He underwent right hemi-colon resection plus lymph-adenectomy under endoscopic guidance. Histologic examination revealed mucinous cystadenocarcinoma dedifferentiated from tubular adenocarcinoma. Two of the twenty lymph-nodes resected were positive for malignancy.
【Discussion】
The size of the tumor was around 9 cm on CT and the macroscopic finding revealed 9.3 cm in tumor size. Although the tumor was big, T classification is not relevant with tumor size but with tumor mural invasion. T classification is as follows; T1 carcinoma in situ (Tis) or intramucosal carcinoma; T2 carcinoma stay in submucosal tissue; T3 carcinoma stay in proximal muscle layer; T4a carcinoma invade to or beyond serosa or adventitia: T4b carcinoma invade to surrounding organ or with distant metastasis (1). Macroscopic examination of the resected specimen in our case revealed carcinoma did not invade to serosa, implying T3.
Lymph node dissection is categorized into three degrees: D1, para-bowel lymph-node dissection; D2, peri-branch artery lymph node dissection or mesentery lymph node dissection: D3, para-trunk artery lymph node dissection. In our patient, he received D3 + D2 + D1 lymph node dissection (1). D3 in our case indicates peri lymph nodes of right colic artery, ileo-colic artery, and middle colic artery since he received right hemi-colectomy.
N classification is as follows; N1a, one lymph node; N1b, two or three lymph nodes; N2a four to six lymph nodes: N2b, seven or greater lymph nodes (1). Histologic examination revealed two lymph nodes were positive for malignancy in our case, implying N2a although CT showed one swollen lymph node sized more than 10 mm.
Microscopically, around 95% of colon cancer is adenocarcinoma (2-4). Adenocarcinoma is categorized into tubular, papillary, poorly, mucinous and signet ring. Signet ring cell carcinoma is rare and found in 1% of the colon-rectal carcinoma. Adenocarcinoma is sub-categorized into solid and non-solid. Mucinous adenocarcinoma is defined that more than a half is occupied by mucin components (1-4). The incidence of mucinous carcinoma is found in around 10-20 % (2-4). In our case, CT showed the tumor at ascending colon contained low-density component more than 50% of the whole mass, indicating the probability of mucinous adenocarcinoma (5), although we could not interpret it.
According to statistical analysis, the organs of the most cancer death are lung, colon, stomach, pancreas and liver, in order. In male, lung, stomach, colon, pancreas and liver, while in female, colon, lung, pancreas, stomach and breast. Five-year survival of all cancer is 59 % : colon cancer, 70.1% (6). In our case, TNM classification was T3N2aM0, indicative of Stage III B. Five-year survival of colon cancer with Stage III B is around 80% after radical surgery and chemotherapy (6).
【Summary】
We present a fifty eight-year-old male with advanced ascending colon cancer T3N1bM0, Stage III B confirmed surgically and pathologically. Laboratory test revealed CEA 31.8 mg/dL. Histologic examination showed mucinous adenocarcinoma. Abdomen CT showed the mass contained low density area more than 50%. It is borne in mind that lymph node dissection D3 indicates para-trunk artery lymph node dissection, T3 carcinoma stay in proximal muscle layer, N1b, two or three lymph nodes. Adenocarcinoma is categorized into tubular, papillary, poorly, mucinous and signet ring. Mucinous adenocarcinoma is found in 10-20 % that more than a half of the mass is occupied by mucin components. Colon cancer of cancers fallen in dead is the second place followed by lung cancer, while the first place in female.
【References】
1.Hashiguchi Y, Japanese Society for Cancer of the Colon and Rectum. Colon and rectum (JSCCR) 2019 for the treatment of colorectal cancer. Int J Clin Oncol. 2019 June 15
2.Nitsche U et al. Mucinous and signet-ring cell colorectal cancers differ from classical adenocarcinomas in tumor biology and prognosis. Ann Surg. 2013:258(5):775-783.
3.Luis I PO, et al. Prognosis of Signet Ring Cell Carcinoma of the Colon and Rectum and their Distinction of Mucinous Adenocarcinoma with Signet Ring Cells. A Comparative Study. Pathol Oncol Res. 2018;24:609-616
4.Kanemitsu Y, et al. Survival after curative resection for mucinous adenocarcinoma of the colorectum. Dis Colon Rectum. 2003;46(2):160-7.
5.Li ZH, et al. Role of CT scan in differentiating the type of colorectal cancer. Onco Targets Ther. 2017;10:2297–2303. doi:10.2147/OTT.S131008
6.Foundation for Promotion of Cancer Research. CANCER STATISTICS IN JAPAN ─ 2018
2020.10.21