In vitro biopsy of colorectal carcinomas

Objective To determine the best part of an ulcerated colorectal neoplasm from which to take a biopsy in order to prove that the lesion is invasive. Patients and methods In this experimental study, biopsies were obtained from 50 ulcerated colorectal tumours using colonoscopic biopsy forceps on the resected specimen after major colorectal resections. Four biopsy sites were chosen, the junction between the normal mucosa and the rolled edge, the top of the rolled edge, the junction between the rolled edge and the ulcer base, and the centre of the ulcer. A code was used so that the pathologist was not aware of the site of each biopsy. Results Biopsies from the very edge of the lesion were positive for carcinoma in 16% of cases, from the top of the roll in 64%, from the inner aspect of the roll in 88% and from the centre of the ulcer in 90%. Conclusion Biopsies from ulcerated colorectal carcinomas are more likely to be positive if taken from the centre of the lesion, rather than the very edge.