Reed Uterine Carcinosarcomas

Abstract

Uterine sarcomas present a challenging group of tumours to manage. They represent a diverse group of tumours and it is argued whether they are true sarcomas. There is now increasing evidence that the carcinosarcomas (CS) – which have been known under a variety of names in the past – are most probably poorly differentiated epithelial carcinomas [1–11]. This switch to propose calling them CS has come from the WHO as well as the International Society of Gynaecological Pathologists. There is a proposal to adopt yet another term, metaplastic carcinomas which may be more helpful in understanding their status [1]. Their molecular profile suggests monoclonality from an epithelial pathway. Nevertheless, historically these tumours have been lumped together and are usually treated by Gynaecological Cancer Specialist teams rather than Soft Tissue Sarcoma Specialists. Historically there were usually three main types of uterine sarcoma – malignant mixed mullerian tumour or MMMT (now known as carcinosarcoma (CS), endometrial stromal sarcomas (ESS), and leiomyosarcomas (LMS)) and a small proportion of unclassifiable high grade tumours with sarcomatous elements. There is a move towards a simpler classification of high grade vs. low grade tumours which takes cognizance of CS not being true sarcomas. Increasingly, CS are recognised and treated as being more akin to poorly differentiated endometrial carcinomas which is supported by their clinical behaviour. Furthermore, there is an increasing recognition on immunocytochemistry and molecular markers that the distinction between LMS and ESS may be more blurred than we previously recognised. This chapter will focus on CS as they most likely are different!