An Unusual Presentation: High-Grade Serous Carcinoma of the Fallopian Tube Manifesting With Altered Mental Status Secondary to a Single Brain Metastasis—A Case Report and Review of the Literature

Epithelial ovarian and fallopian cancers are aggressive lesions that rarely metastasize to the central nervous system. Brain metastases usually occur in the setting of known primary disease or widespread metastatic disease. However, in extremely rare cases, an isolated intracranial neoplasm may be the first presentation of fallopian cancer. To the best of our knowledge, only one such case has been reported previously. We present an illustrative case with multimodality imaging and histopathologic correlation of a fallopian tube carcinoma first presenting with altered mental status secondary to an isolated brain metastasis. A 64-year-old female with no pertinent medical history presented with altered mentation. Initial workup identified a 1.6 cm avidly enhancing, solitary brain lesion at the gray-white junction with associated vasogenic edema concerning for either central nervous system lymphoma or metastatic disease. Additional imaging identified a 7.5 × 3 cm left adnexal lesion, initially thought to be a hydrosalpinx with hemorrhage, but magnetic resonance imaging suggested gynecologic malignancy. No lesions elsewhere in the body were identified. Given the lack of locoregional or systemic disease, the intracranial and pelvic lesions were assumed to represent synchronous but distinct processes. The intracranial lesion was biopsied. Preliminary results were suggestive of lymphoma, but further analysis was consistent with high-grade serous carcinoma of müllerian origin. Positron emission tomography/computed tomography was performed to evaluate for other neoplastic lesions, only highlighting the intracranial and pelvic lesions. At this point, a diagnosis of metastatic fallopian cancer was made. The patient was taken for robot-assisted laparoscopy with surgical debulking of the pelvic neoplasm, pathology demonstrating high-grade serous carcinoma of the fallopian tube, matching that of the intracranial lesion. Even though rare, metastatic fallopian cancer should be considered in patients with isolated brain lesions and adnexal lesions, even in the absence of locoregional or systemic disease.