Immunocytochemical localization of lymphatic and venous vessels in colonic polyps and adenomas

Tumour Cell Seeding to Lymph Nodes from In Situ Colorectal Cancer

Lymph node (LN) metastasis is an important prognostic factor in colorectal cancer (CRC). We aimed to demonstrate the presence of lymphatic vessels (LV) in the mucosa of in-situ (pTis) CRC, and of detectable tumour burden in regional LNs. This is an observational retrospective study of 39 surgically resected in situ CRCs. The number of LVs was evaluated in both pTis and normal mucosa using D2-40 immunostains. All LNs were assessed with both H&E and the One Step Nucleic Acid Amplification (OSNA) assay, and the results were correlated with clinicopathological features. D2-40 immunohistochemisty revealed LVs in the lamina propria of all pTis CRC (100%), being absent in normal mucosa. A median of 16 LNs were freshly dissected per patient, and all cases were pN0 with H&E. Molecular LN analysis with OSNA revealed the presence of low amounts of tumour burden in 11/39 (28%) cases (range 400 to 4270 CK19 mRNA copies/µL), which had no clinical consequences. This study demonstrates the presence of LVs in the lamina propria in 100% of pTis CRC, as well as the presence of low amounts of tumour burden in regional LNs, only detected by molecular methods. Given the prognostic value of LN tumour burden, its molecular quantification may help a patient's clinical management.

Localization of nerve fibers in colonic polyps, adenomas, and adenocarcinomas by immunocytochemical staining for PGP 9.5

BACKGROUND

PGP 9.5 is a cytoplasmic protein and is a specific marker for neurites and neurons.

AIMS

Using anti-PGP 9.5, this study aimed to localize nerve fibers in normal colons, polyps, adenomas and adenocarcinomas.

METHODS

Colonic polyps, adenomas and T(1) to T(3) adenocarcinomas with adjacent normal colon were immunostained for PGP 9.5 using rabbit anti-PGP 9.5.

RESULTS

In normal colon, numerous nerve fibers were localized in inner and outer muscles, from which submucosa and lamina propria were innervated. In hyperplastic polyps and tubular adenomas, the stalk revealed Meissner's plexus and large-diameter nerve fibers, and fine nerve fibers innervated abundantly in lamina propria of hyperplastic polyps and small tubular adenomas. In villous adenomas, large-diameter nerve fibers and Meissner's plexus were localized in the stalk whereas a few or no fine nerve fibers were localized in fine stroma. In adenocarcinomas, more fine fibers were localized in submucosal stroma adjacent to the invading carcinoma in T(1) carcinomas but there were no nerve fibers in the midst of tumors in T(2) and T(3) carcinomas. There were focally and sporadically increased nerve fibers adjacent to invading cancer nests in 5 of 8 T(2) cases. In T(3) carcinomas, fragmented Auerbach's plexus were noted in cancer-invaded colonic muscles and there were no increased fine nerve fibers in the cancer-invaded subserosa in the majority of cases. PGP 9.5 immunostaining revealed tumor-associated neurogenesis in submucosa but no obviously increased nerve fibers within cancer-invaded muscles.

CONCLUSIONS

This lack of tumor-associated neurogenesis supports insidious and often silent clinical presentation of colonic carcinomas until invading through the colonic wall to adjacent organs.

Lymphatic patterns of colorectal liver metastases

BACKGROUND

Hematogenous spread is considered the predominant pathway for development of colorectal liver metastases (CRLM) and subsequent further tumor dissemination portal nodal involvement is also frequently observed in such cases, suggesting that lymphatics may have a role in the spread of CRLM. The role of lymphatics in the development of liver metastases is, however, controversial. The lymphatic patterns of CRLM were determined using a well established murine model.

METHODS

CRLM were induced using a well established murine intrasplenic colorectal cancer model. Tumors were assessed at varying stages of development, and lymphatic patterns were determined in tumors and liver by immunohistochemistry staining for podoplanin and LYVE-1. Blood vessels were characterized using the vascular marker CD-34. Assessment was undertaken using digital microscopy and image analysis.

RESULTS

Peri- and intratumoral lymphatic vessels were identified by podoplanin staining in all metastases and significantly increased with tumor growth. LYVE-1 staining was also noted but was variable. There was a concurrent significant increase in portal lymphatic staining within the normal liver with increasing growth of CRLM.

CONCLUSION

There is increased expression of lymphatics within CRLM and normal liver with increasing tumor growth. Lymphatic development is likely to play a significant role in the intrahepatic and periportal dissemination of CRLM.