A postmenopausal woman with lobular breast carcinoma metastatic to a large ovarian fibrothecoma is presented. The two metastatic tumor nodules were grossly subtle and could have been overlooked in the background of the large ovarian stromal tumor. Thorough sampling of the tumor for histologic examination and supporting immunohistochemical stains were important in establishing the diagnosis. Differential diagnostic considerations are discussed.
Keywords: Lobular breast carcinoma; collision tumor; fibrothecoma; immunohistochemistry.