Invasive Squamous Cell Carcinoma

Abstract

We see so few invasive squamous cell carcinomas these days that we have a paucity of cases to use as illustrations. As such, we have included the few cases we have seen recently. Some invasive squamous carcinomas keratinize whereas other do not, and the amount of keratin formation varies from a tiny focus to a lot. The cancers also vary in differentiation from very well (a good caricature of normal) to very poorly, which looks nothing like normal. In the 2010 World Health Organization book [1], invasive squamous cancers are divided into well, moderate, and poor differentiation, with mention that the most common type is moderately differentiated, but there are no definite histologic criteria for making this determination. What is apparent is that a squamous esophageal carcinoma is likely to be heterogeneous with different areas looking quite different histologically. We have chosen to illustrate different squamous cancers and we will leave it to the reader to determine the degree of differentiation of each tumor. The issue of incipient invasion into the lamina propria is covered in depth at the end of Chap. 6.