Clear cell carcinoma of the ovary arising in a mucinous cystadenoma

A 57 year old woman presented complaining of increasing abdominal swelling of six months duration. A mixed solid cystic left ovarian tumour measuring 24 cm in diameter was excised. Histology showed numerous cysts lined by ben ign mucinous epithelium blending imperceptibly into borderline clear cell a nd mucinous areas that in turn merged with an invasive clear cell carcinoma . To the best of our knowledge, this is the first reported case of clear ce ll carcinoma arising in a mucinous cystadenoma. The implications for the pr eviously postulated pathogenesis of these tumours are discussed.