Silent corticotroph cell pituitary adenoma in a struma ovarii.

This is the first report of a silent corticotroph cell pituitary adenoma arising in a struma ovarii. The patient, a 79-year-old woman, was found to have an asymptomatic left-sided adnexal mass confirmed by vaginal sonography to be a complex cystic and solid tumor. Pathological analysis demonstrated an 8-cm partially cystic struma ovarii in which there was a focus of predominantly basophilic adenohypophyseal cells arranged in a diffuse pattern, adjacent to mature neural tissue containing numerous Herring bodies. The epithelial lining cells of the colloid-filled small and cystic follicles were immunoreactive for thyroglobulin. The pituitary cells were predominantly immunoreactive for adrenocorticotropic hormone, in addition to synaptophysin.