Clinicopathological characteristics in large, non-polypoid colorectal adenomas with granule-aggregating appearance

Endoscopically, most large, non-polypoid colorectal adenomas have a granule-aggregating appearance, made up of elevations of small, flat lesions projecting above the surrounding mucosa. In this study we investigated the clinicopathological characteristics in 26 cases of such tumours and proposed the term 'granule-aggregating tumour' (GAT). Patients with GATs (16 men and 10 women) had a mean age of 64.3 years (range, 38-83 years). The mean diameter of the GATs was 28 mm (range, 12-62 mm). Histologically, GATs were diagnosed as tubular (15 cases) or tubulovillous (11 cases) adenomas without submucosal invasion. These tumours had a surface morphology comprised mainly of small, flat elevations or granular structures, measuring 1.2 +/- 0.3 mm in diameter. Of the 26 patients with GATs, 19 (73.1%) were asymptomatic and 11 of these 19 cases (57.9%) were detected by a faecal occult blood test. In nine of the 26 patients (34.6%) GATs were accompanied by colorectal cancers arising at other sites. GATs show typical endoscopic features, often lack symptoms and are frequently accompanied by other cancers in other organs. An awareness of the existence of GATs should assist in the screening, prevention and therapy of colorectal tumours.