• colorectal cancer
• veins
• histopathology

We read with interest the recent paper by Dirschmid et al. 1 

The authors assessed the prevalence of extramural venous invasion (EMVI) and its association with metachronous visceral metastases in 27 pT2 and 12 pT1 colorectal carcinomas (CRCs) using a modified protocol that included tangential macroscopic dissection. None of the pT1 tumours showed EMVI or developed visceral metastasis. In contrast, EMVI was identified in 3/27 (11.1%) pT2 tumours, of which 2 developed metachronous visceral metastases. This work deserves special consideration for several reasons.

Venous invasion (VI) is a strong adverse prognostic factor and a powerful predictor of haematogenous metastases in CRC, accounting for most of cancer-related deaths.2 3 Despite its prognostic importance, VI is under-reported, with wide variation in published VI detection rates (10%–89%). Such variation may reflect differences in patient selection, macroscopic sampling techniques, number of tumour-containing blocks submitted, diagnostic criteria, use of special stains, and diligence and skill of the reporting pathologist.2 4–6 The diagnosis of VI in CRC specimens can be challenging on conventional H&E stains alone, and easily missed if morphological clues (eg, ‘orphaned artery’ and ‘protruding tongue’ signs) are not recognised.2 6 Elastin stains have been shown to enhance the detection of VI, increasing detection rates by twofold to threefold.5 7 As such, the CRC protocols of the College of American Pathologists (CAP) and Royal College of Pathologists (UK) …