RESUMO
Primary fallopian tube carcinoma (PFTC) is seldom diagnosed preoperatively and is often mistaken for epithelial ovarian carcinoma (EOC). This report details a case of primary high-grade serous carcinoma (HGSC) of the fallopian tube, highlighting radiological and clinical indicators to aid in accurate diagnosis and avoid misdiagnosis. A 46-year-old premenopausal woman presented with symptoms and a transvaginal ultrasound (TVUS) indicating a malignant ovarian tumor. Further imaging with CT and MRI revealed a solid-cystic mass suggestive of a fallopian tube tumor rather than an ovarian origin. Oncological surgery confirmed the presence of a high-grade serous carcinoma in the fallopian tube. This case underscores the diagnostic challenges of PFTC and the superior sensitivity and specificity of MRI over CT and US in distinguishing adnexal lesions. Key MRI features such as the sausage-shaped mass and associated hematosalpinx were crucial in differentiating PFTC from EOC. The report emphasizes the importance of considering PFTC in differential diagnoses of adnexal masses to ensure accurate preoperative identification.