Mucin producing carcinoid tumours of the vermiform appendix.

Six cases of an unusual mucoid variant of carcinoid tumour of the appendix are reported. These lesions are small, detected incidentally, and carry a good prognosis. Their histological features are distinctive and differ from those of ordinary carcinoid tumours and adenocarcinoma. They have been confused with adenocarcinoma, sometimes resulting in radical surgery. Surgery beyond appendicectomy is probably unwarranted in these cases. The mucin secreted by goblet cells of the normal mucosal epithelium and by the cells of these carcinoid tumours have certain histochemical similarities.