The benefits of elastica – no stretch of the imagiaction

Venous invasion is a well‐established prognostic factor in colorectal cancer and is an independent prognostic indicator of visceral metastases and decreased survival time.¹,²,³,⁴ Unfortunately, the use of only conventional haematoxylin and eosin staining to determine the incidence of venous invasion has yielded a wide range of results (10–90%).¹,²,³,⁴,⁵,⁶ In the July 2004 publication of the Journal of Clinical Pathology, Vass et al⁷ showed that using an elastica stain considerably increased the sensitivity of identifying venous invasion in colorectal cancer. Their study was carried out in a university teaching hospital by a specialist in colorectal pathology, as opposed to the original reports, which were made by a large team of non‐specialists. The aim of our study was to determine whether using this technique had a similar benefit in the district general hospital setting with non‐specialist reporting.

Methods

From our local database of colorectal audit forms, we identified 100 colorectal tumour resections, during the period 12 October 2003 to 31 December 2004, reported as having no evidence of extramural vascular invasion. A single section was cut from tumour blocks (three per case), stained with elastica and counterstained with haematoxylin and eosin. A trainee pathologist (GS) and a consultant pathologist (AR) assessed the presence of both extramural and intramural venous invasion. Controversial cases were examined through a double‐headed microscope.

Results

Figure 1 details the results for the 100 tumour specimens examined using an elastica haematoxylin and eosin stain.

Figure 1 Incidence of vascular invasion shown by staining with elastica haematoxylin and eosin.

Of the 100 specimens (all of which had previously been reported as negative for extramural venous invasion by conventional haematoxylin and eosin staining), 17% were found to have extramural venous invasion by using sections stained with elastica haematoxylin and eosin. Nine of the tumour specimens showed extramural venous invasion only, whereas eight contained both intramural and extramural venous invasion. The presence of intramural venous invasion was not recorded in the final reports of any of these 17 specimens.

Eighty three specimens showed no evidence of extramural venous invasion on staining with both conventional haematoxylin and eosin and elastica haematoxylin and eosin. Intramural venous invasion was identified by elastica haematoxylin and eosin staining in 19 of these specimens, of which intramural venous invasion was recorded in the final report of two specimens.

Conclusion

In this study, extramural venous invasion was identified in 17% of the patients by the addition of an elastica haematoxylin and eosin stain (fig 2). As the identification of extramural venous invasion is an important independent prognostic factor in colorectal adenocarcinomas, it is clear from our results that the addition of an elastica haematoxylin and eosin stain yields important prognostic information. This result is similar to that of Vass et al,⁷ who identified an additional 19% of specimens with extramural venous invasion in 75 specimens examined.

Figure 2 Extramural venous invasion. An artery (top left) is shown, with the adjacent vein (bottom right) containing tumour. Elastica staining highlights the elastic fibres of both the artery and the vein.

Intramural venous invasion was identified in 27% of the specimens by staining with elastica haematoxylin and eosin, but was recorded in only two of the final histological reports, as it was not part of the minimum dataset. Vass et al⁷ showed a similar increase in detection of intramural vascular invasion from 10% to 29% by the addition of an elastica haematoxylin and eosin stain. We noted that many cases of intramural venous invasion embedded deep in the tumour mass are difficult to identify by conventional haematoxylin and eosin staining, but are highlighted by elastica staining (fig 3). Several cases of extramural venous invasion were similarly embedded in the tumour mass and were thus difficult to identify without an elastica haematoxylin and eosin stain. Intramural vascular invasion is not currently accepted as an independent prognostic factor in colorectal cancer. With the use of elastica haematoxylin and eosin staining, future studies may elucidate the prognostic significance of this finding.

Figure 3 Intramural venous invasion. Elastica stain highlights a vein (10 o'clock of centre) containing tumour. As this vein is embedded in the tumour, it is difficult to identify by conventional haematoxylin and eosin staining. This phenomenon is also seen in extramural venous invasion.

In conclusion, our findings in the non‐specialist reporting department of a district general hospital support those of Vass et al⁷ and provide further evidence for the value of incorporating an elastica haematoxylin and eosin stain in the standard histopathological reporting of colorectal adenocarcinomas.