Carcinoid tumours of the rectum and anus.

Carcinoid tumours of the anorectum comprise only 0.1 per cent of all rectal tumours. Their behaviour and treatment are still debatable. We identified 35 cases from the records of St Mark's Hospital; 31 were benign and 4 were malignant. Benign tumours were of three distinct histopathological patterns. All benign tumours were cured by local treatment. Malignant tumours can be identified clinically; the only consistent microscopic feature was invasion of the muscularis propria. All patients with malignant tumours died, despite radical surgical treatment; lymph node metastases were invariably present in the operation specimens. Because radical treatment for malignant carcinoid tumours of the anorectum is largely unsuccessful, a flexible surgical approach is advocated.