Lymph Nodes

Lymph nodes and liver are the commonest sites of metastases. Also peritoneum, lung, and ovaries and bladder where the metastases can mimic primary carcinoma of those organs. Immunophenotypical profiles may aid distinction, e.g. ovarian cancer is cytokeratin 7 positive/20 variable and weak for CEA, whereas gut cancer is strongly CEA positive and cytokeratin 7 negative/20 positive. Occasional colorectal cancers express CK7 and a minority are CK20 negative, particularly those with a high level of microsatellite instability, e.g. HNPCC.

Site/number/size/number involved/limit node/extracapsular spread. Regional nodes: pericolic, perirectal, those located along the ileocolic, colic, inferior mesenteric, superior rectal and internal iliac arteries. A regional lymphadenectomy will ordinarily include a minimum of 12 lymph nodes. Lymph node yield varies greatly even after careful dissection. It is related to variation in individual anatomy, site (mesorectum yields few nodes), the extent of resection performed, and history of pre-operative adjuvant therapy. External iliac, common iliac and superior mesenteric artery nodes are distant metastases.

pN0 no regional lymph node metastasis pN1 1-3 involved regional lymph nodes pN2 4 or more involved regional lymph nodes

Dukes' C1 nodes involved but apical node negative

Dukes' C2 suture tie limit apical node positive.

All regional lymph nodes should be sampled for histology:

— a minimum target of eight will identify the vast majority of Dukes' C lesions. Recent data recommend 10 as a minimum and that finding more than 15 does not confer additional benefit, although this is not universally accepted.

— remember to assess the small lymph nodes seen on histology adjacent to the tumour margin. The biological significance of nodal micrometastases (<0.2cm) is uncertain.

pTis pTI

Epithelium

Lamina propria Muscularis mucosae

Submucosa

Muscularis propria

Mesocolic/ mesorectal tissue d= tumour distance (mm) from the muscularis propria and is an index of mesorectal/mesocolic spread. D=tumour distance (mm) to the Circumferential Radial Margin (CRM) of excision of either continuous or discontinuous tumour extension or tumour in a lymphatic, lymph node orvessel. It is an index of adequacy of local excision and degree of spread.

Subserosa

Serosa

OR adjacent organs e.g. bowel and structures e.g. sacrum

Figure 5.3. Colorectal carcinoma. ¡OA!

Figure 5.4. Kaplan-Meier cumulative survival curve for pertoneal involvement (Shepherd NA, Baxter KJ, Love SB. Influence of local peritoneal involvement on pelvic recurrence and prognosis in rectal cancer. J Clin Pathol 1995;48:849-855. Reproduced with permission from the BMJ Publishing Group). Group 1, tumour well clear of the closest peritoneal surface; group 2, mesothelial inflammatory/ hyperplastic reaction with tumour close to but not actually at the peritoneal surface; group 3, tumour present at the peritoneal surface with inflammatory reaction/mesothelial hyperplasia/"ulceration"; group 4, tumour cells free in peritoneum and adjacent "ulceration".

Figure 5.4. Kaplan-Meier cumulative survival curve for pertoneal involvement (Shepherd NA, Baxter KJ, Love SB. Influence of local peritoneal involvement on pelvic recurrence and prognosis in rectal cancer. J Clin Pathol 1995;48:849-855. Reproduced with permission from the BMJ Publishing Group). Group 1, tumour well clear of the closest peritoneal surface; group 2, mesothelial inflammatory/ hyperplastic reaction with tumour close to but not actually at the peritoneal surface; group 3, tumour present at the peritoneal surface with inflammatory reaction/mesothelial hyperplasia/"ulceration"; group 4, tumour cells free in peritoneum and adjacent "ulceration".

— comment if an involved lymph node lies adjacent to (<1 mm) the mesorectal CRM (circumferential radial margin) or mesocolic margin as this equates to involvement of that margin.

— direct invasion into a node is regarded as a nodal metastasis.

— a tumour nodule >3 mm in diameter in the perirectal/pericolic fat without evidence of residual lymph node is classified as a replaced nodal metastasis. If <3mm diameter classify as discontinuous extension, i.e. pT3. It is important to note that this is a 5th edition TNM rule. The 6th edition TNM rule, which probably more accurately reflects biological events, is: a tumour nodule in the pericolic/perirec-tal adipose tissue without histological evidence of residual lymph node in the nodule is a lymph node metastasis if the nodule has the form and smooth contour of a lymph node. If of irregular contour it is classified as discontinuous pT3 spread and also as microscopic (V1) or macroscopic (V2) venous invasion as this is its likely origin. In the UK the Royal College of Pathologists has recommended using TMN 5 rather than TMN 6 due to concerns over the validity of ongoing clinical trials and the observer reproducibility in applying TNM 6. The resolution of this issue awaits further studies. In either case it should be ensured that the nodule does not represent tumour in an identifi-

able extramural vein and in practice pathologists often use a combination of these rules. — more than one vascular pedicle suture tie may mean more than one apical node needs to be identified as such.

Was this article helpful?

0 0
10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

Get My Free Ebook


Post a comment