On the histogenesis and morphology of ovarian carcinomas

The modern classification of ovarian tumors based on histogenetic principles is clinically important in the evaluation of prognosis and differential therapy. Ninety percent of malignant ovarian tumors belong to the category of "common carcinomas." All of these tumors originate from the coelomic epithelium at any of various stages of its differentiation into the derivatives of the Müllerian duct, giving rise to a large group of tumors that can be subdivided into serous papillary cyst-adenocarcinomas arising from surface-like epithelium, mucinous cystadenocarcinomas arising from endocervical-like epithelium, endometrioid carcinomas from endometrium-like epithelium, clear-cell carcinomas from endocervical or endometrium-like epithelium, malignant cystadenofibromas from undetermined pluripotent Müllerian epithelium, and (malignant) Brenner tumors from heterotopic epithelium resembling Wolffian differentiation, as seen in the urothelium. The well differentiated stages of these carcinomas can be readily distinguished by comparing them with the derivates of the Müllerian epithelium. The poorly differentiated types, on the other hand, may provide no criteria for comparison, but can still be classified as belonging to the group of common epithelial tumors. Adenocarcinomas of one type may also contain portions of another related type, e.g., serous papillary carcinomas may contain mucinous glands or groups of clear cells and vice versa. Serous papillary carcinomas form the largest group containing about 50% of all ovarian carcinomas. The endometrioid carcinomas comprise roughly 20%, the mucinous carcinomas 10%, and the VXGHb-cell carcinomas roughly 10%. Five percent of all carcinomas are unclassifiable and the remaining 5% constitute the group of rare ovarian carcinomas: the malignant cystadenofibromas, adenosarcomas, malignant mesenchymal mixed tumors, and malignant Brenner tumors. The three main groups can be histologically subdivided into three grades: those of high, moderate and poor differentiation. In addition, a borderline tumor representing a pre-stage of invasion and metastasis has been recognized. The prognosis with serous papillary carcinomas is poor, with an overall 5-year survival rate of 20%; the 5-year survival rate for mucinous carcinomas is 40%-60%, for endometrioid carcinomas 55%, and for clear-cell carcinomas 40%. Statistically significant data for predicting the prognosis for rare carcinomas are not available.