An unexpected immunohistochemical profile in an ovarian lesion

A 27 year old female presented with pelvic pain and a palpable pelvic mass. Upon histological examination, the cystic mass contained a multi-cellular lining with nuclear grooves. Negative inhibin staining ruled out a follicular cyst and granulosa cell tumor while pan-cytokeratin positivity suggested an epithelial lesion. The lesion stained positive for thrombomodulin, ultimately suggesting a diagnosis of a Brenner cell tumor, although CD56 positivity in the tumor questions the known immunohistochemical profile of Brenner cell tumors. This unusual result opens the door to future research into the role CD56 in the diagnosis of ovarian neoplasms