**6.1 Pathology of ovarian clear cell carcinomas**

Grossly, OCCCs are large (mean size 13 cm) unilateral masses, solid and cystic in appearance, frequently containing endometriosis lesions. Microscopically, they have solid, tubulocystic and papillary architectural patterns and are composed of neoplastic cells characterised as polygonal, cuboidal or hobnail-like cells with clear cytoplasm, atypical nuclei and distinct nucleoli, without prominent pleomorhism [5, 122]. Mitotic activity is less than 5 mitoses per 10 high power fields. The clear cytoplasm is glycogen rich, PAS positive and diastase sensitive. Stromal hyalinization and myxoid appearance can be seen frequently [5].
