Colonic neoplastic polyps: biopsy is not efficient to exclude malignancy. The Trafford experience

Abstract

The biological behaviour of the polyp depends entirely on its histological subtype. Adenomas are the classic precursors to carcinoma. Polyp biopsy can differentiate neoplastic (adenoma and carcinoma) from non-neoplastic polyps (hyperplastic, inflammatory, hamartomatous). Due to potential sampling error, biopsy does not always differentiate between adenoma and carcinoma. Our aim was to investigate the degree of this potential sampling error. We carried out a study to compare the results of biopsies vs. total tissue examinations in a cohort of 433 neoplastic polyps. In this study 18.5% of carcinomatous polyps show definitive malignant elements only when the entire polyp is presented to the pathologist. We have therefore adopted a special reporting template if the polypoidal tumour is either biopsied or incompletely excised. The study also showed that within adenomas there could be variance of architectural patterns between the biopsy and the whole specimen. In this series, biopsying malignant colonic polyps gives rise to 18.5% false negative results and therefore it is significantly less efficient in the diagnosis of malignancy compared to total polyp examination.

Transanal Endoscopic Surgery With Total Wall Excision Is Required With Rectal Adenomas due to the High Frequency of Adenocarcinoma

“…10 the risk here is that the excision will not prove curative and, above all, an accurate histological diagnosis of the lesion may not be obtained. 11 in our experience, 12,13 the percentage of invasive adenocarcinomas among rectal adenomas is high. We therefore advocate total excision of the wall for all rectal tumors that can be treated with local surgery.…”

The malignant adenoma: when to operate and when to watch

“…It has been shown that when making a diagnosis of malignancy in an adenoma following a biopsy a false-negative rate of 18.5% occurs when compared to examining the entire specimen [21]. Therefore it is important to realise that, to make a definitive diagnosis of an adenoma and rule out malignancy, the pathologist must look at the entire specimen.…”

Adenomas with Adenocarcinoma: A Study Evaluating the Risk Of Residual Cancer And Lymph Node Metastasis

“…Several studies have shown that the rate of adenocarcinoma in adenomas in biopsies is underestimated when compared with later total polypectomy (15,16). The excision margins have also been discussed.…”