Ovarian mucinous and seromucinous neoplasms: problematic aspects and modern diagnostic approach.

The morphological spectrum of primary ovarian mucinous and seromucinous tumours is broad, and presents an array of diagnostic challenges, many unique to these tumour types. This reflects the heterogeneous nature of these lesions, their varied histogenesis and evolving classification systems over recent decades, with further modification to the seromucinous category incorporated in the recently published 5th edition of the World Health Organisation (WHO) Classification of female genital tumours. In this review we provide an update on the classification of these neoplasms and discuss their histogenesis and diverse morphology, focusing on areas which are diagnostically problematic. We also cover tumour grading, differential diagnosis, immunohistochemistry, the recent elucidation of the molecular underpinnings of ovarian mucinous neoplasia and discuss the gross and intra-operative handling of these tumours. A number of diagnostic issues remain unresolved, highlighting the importance of further research on this front, as well as a multidisciplinary approach in the care of patients with ovarian mucinous and seromucinous neoplasia.