Although the histological typing of ovarian tumours is the focus of this volume, other aspects of investigation of a specimen of ovarian tumour are also important. Some of these aspects are mentioned in the text or illustrated. They include tumour grading, which is impor- tantprognostically and therapeutically for certain types ofovarian tu- mour, quantification ofcomponents in mixed tumours and evaluation of the stroma of certain tumours that are associated with endocrine function. Grading methodologies have varied from one tumour type to another and from one group of investigators to another for the same type of tumour. Because a standard internationally recognized grading methodology has not been established, no specific guidance is presented in this volume. Nevertheless, grading by any generally acceptable method should be incorporated in the diagnosis whenever appropriate. The clinical and pathological classification of the extent of tu- mour growth (staging) should be taken into account for the purposes of treatment and prognosis. The TNlV1/FIGO system is therefore in- cluded (p. 45). Histological Classification of Ovarian Tumours 1 Surface Epithelial-Stromal Tumours 1. 1 Serous tumours 1. 1. 1 Benign 1 1. 1. 1. 1 Cystadenoma 8441/0 Papillary cystadenoma 8460/0 1. 1. 1. 2 Surface papilloma ...8461/0 1. 1. 1. 3 Adenofibroma; cystadenofibroma ...9014/0 1. 1. 2 Of borderline malignancy (of low malignant potential) 2 1. 1. 2. 1 Cystic tumour 8442/1 Papillary cystic tumour ...846211 Surface papillary tumour...8463/1 1. 1. 2. 2 1. 1. 2. 3 Adenofibroma; cystadenofibroma 9014/1 1. 1.