Clear cell carcinoma (CCC) of the ovary is probably the single most recognizable type of ovarian carcinoma at the histopathologic level. Architecturally, the picture is one of micropapillary, tubulocystic, solid, or adenofibromatous patterns, or admixtures of two or more of these. Prominent stromal hyalinization is also a feature easily identifiable at low magnification. The dominant cells of ovarian CCC are characterized as either clear or hobnail cells, and again admixtures of the two cell types are common. One of the unique features of CCC is the presence (focally or diffusely) of bizarre nuclear atypia in the absence of prominent mitotic activity (almost all CCC having mitotic counts of less than 5 per 10 high-power fields).