World Health Organization classification and nomenclature of ovarian cancer.

A World Health Organization (WHO) committee of representatives from seven nations published a histologic typing of ovarian tumors in 1973. Their typing of common epithelial tumor was based largely on the classification by the International Federation of Gynaecology and Obstetrics (FIGO), and the single most important concept to emerge from the FIGO and WHO classifications was the distinction among common epithelial tumors between tumors of borderline malignancy and carcinomas. A second general category of ovarian tumors, some of which are clinically malignant, was designated by the WHO committee as sex cord-stromal tumors (neoplasms containing granulosa, theca, collagen-producing stromal, Sertoli, and/or Leydig cells). The WHO classification of germ cell tumors emphasized the necessity of careful examination of the gross specimen with jucicious sampling for microscopic evaluation. The classification and nomenclature used within an institution should be the one most conductive to mutual understanding and optimal patient care; however, when that nomenclature has to be translated into one with more widespread acceptance, the WHO classification, based on the earlier and widely adopted classification of FIGO, is presently the most deserving of universal usage.