Ovarian neoplasms are notoriously heterogeneous-the World Health Organization classification (1 ) includes 46 different epithelial tumor types, 24 sex cord stromal types, 29 germ cell types, and 13 other categories, not including 17 other tumor-like conditions (Table 1).Many of these lesions are very rare, but there is tremendous variation in the biological behavior of different tumor types, and it is very important that histopathological assessment is performed accurately. This is not only crucial to the patient, whose treatment depends on it, but also in investigative work on ovarian cancer. Uniform terminology must be used to allow comparisons between different studies and any research that involves analysis of the biological or clinical features of ovarian tumors must include expert histopathological review of cases.
