ABSTRACT
The majority of malignant tumours of the large intestine are adenocarcinomas. Other less common tumours with the same histogenesis, but with differing histological appearances, i.e. adenosquamous carcinoma and squamous carcinoma, resemble adenocarcinoma in clinical behaviour and may logically be grouped together with adenocarcinoma. With an adequate biopsy colonic carcinomas do not usually present any diagnostic difficulty, but problems may arise in deciding if small irregular fragments contain malignant glands or whether the tissue is part of an adenoma. Questions such as this and other diagnostic problems are discussed in Chapter 16.
