Mucinous tumours of the ovary

Mucinous tumours of the ovary demonstrate marked morphological diversity, both within the group as a whole and in individual tumours. In this review, we focus on practical problems in interpretation and nomenclature. Recent developments of significance, including the recognition of Müllerian mucinous tumours and the distinction of expansile from destructive stromal invasion in carcinomas, are reviewed. Intriguing phenomena such as the occurrence of mural nodules that range from reactive proliferations to anaplastic carcinoma are discussed, as are other varied findings such as occasionally prominent mucin granulomas and rare primary tumours with focal signet ring cell morphology. The problematic area of metastatic mucinous neoplasia is considered. The gross and histological features of secondary mucinous neoplasia are reviewed, with specific comments regarding tumours arising from the appendix, which are associated with particular features when they spread to the ovary. The famous Krukenberg tumour is briefly discussed because of its definitional content of mucin-filled signet ring cells. Finally, the enigmatic occurrence of mucinous epithelial cells in a variety of ovarian tumours not traditionally considered ‘mucinous’ is noted. The latter include sex cord tumours, usually Sertoli-Leydig cell tumours but occasionally granulosa cell tumours, and entities as different as benign Brenner tumours and highly-malignant small cell carcinomas of hypercalcaemic type.