Use of an elastic stain to show venous invasion in colorectal carcinoma: a simple technique for detection of an important prognostic factor.
BACKGROUND
Venous invasion (VI) is an important prognostic factor in colorectal cancer; it is positively associated with visceral metastases and may affect the decision to treat with adjuvant therapy.


OBJECTIVE
To evaluate whether an elastic tissue (Movat) stain facilitates identification of VI, the number of Movat-stained blocks needed to detect VI, and whether VI identified with a Movat stain is prognostically equivalent to VI identified on H&E-stained slides.


METHODS
H&E-stained sections from colorectal carcinomas from the year 2000 (n = 92) were examined for VI and compared to Movat-stained slides. Clinical charts were reviewed to compare rates of metastases in VI-positive versus VI-negative patients.


RESULTS
With the Movat stain, VI was identified in 44% of cases previously categorised as negative (p<0.001) on review of H&E slides alone. One Movat-stained section was often sufficient to identify VI, with a statistically significant benefit to performing multiple stains if necessary. In H&E sections, two clues helped identify VI: the "unaccompanied artery" sign, where large arteries were seen without an accompanying vein; and the "protruding tongue" sign, where smooth tongues of tumour extended into pericolic/rectal fat. Metastases were present in 61% of cases positive for VI compared to 35% in VI-negative cases (p = 0.03). 45% of cases positive for intramural VI only developed metastases (p = 0.39), while 65% of cases positive for extramural VI only developed metastases (p = 0.03).


CONCLUSIONS
Pathologists should look for morphological clues of VI in H&E stained sections; when VI is not apparent, an elastic tissue stain on all tumour blocks significantly improves identification of VI. Morphological clues include the "unaccompanied artery" and "protruding tongue" signs.
Department of Pathology, London Health Sciences Centre and University of Western Ontario, London, Ontario, Canada.
C J
CJ
Howlett
E J
EJ
Tweedie
D K
DK
Driman
D000230:Adenocarcinoma / Q000473:pathology* / Q000556:secondary / Q000628:therapy; D001808:Blood Vessels / Q000473:pathology*; D017024:Chemotherapy, Adjuvant; D015179:Colorectal Neoplasms / Q000473:pathology* / Q000628:therapy; D004547:Elastic Tissue / Q000473:pathology; D006801:Humans; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011379:Prognosis; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D013048:Specimen Handling / Q000379:methods; D013194:Staining and Labeling / Q000379:methods; D016896:Treatment Outcome