[Carcinoids of the rectum]

A total of 8 carcinoids of the rectum were investigated. The group of carcinoids was not uniform even when their anatomical localization was the same. Depending upon the histological structure of carcinoids two main morphological variants were singled out: cellular-alveolar and band-solid. In some part of the tumoral cells of all carcinoids there were revealed lipids, mucus, at the same time in no case argentaffine granulation was observed. Muculent stromas were characteristic of all carcinoids of this localization. Invasion of the muscular layer, their size being more than 2 cm, should be considered as a sign of malignancy of carcinoids. The presence of fat and mucus the absence of argentaffine granulation in cells of the tumour cannot be regarded as proofs of malignancy of carcinoids.