Ovarian Metastasis from Invasive Lobular Carcinoma of the Breast: A 6-Case Series with Emphasis on Diagnostic Challenges and the Value of Biopsy

Background: Invasive lobular carcinoma (ILC) of the breast has a unique metastatic pattern due to E-cadherin deficiency, with a predilection for peritoneal, gastrointestinal, and pelvic organ involvement. Ovarian metastasis from ILC is rare but can mimic primary ovarian cancer clinically and radiologically, leading to misdiagnosis and unnecessary radical surgery. This study aimed to summarize the imaging features of ovarian metastasis from ILC and analyze the causes of misdiagnosis, while highlighting the value of preoperative biopsy. Methods: Clinical and imaging data of six patients with pathologically confirmed ovarian metastasis from ILC were retrospectively analyzed. All six patients were female (age range 33–65 years), had a history of breast cancer (ILC subtype), and were found to have ovarian masses either during follow-up or at initial diagnosis. Imaging findings of the ovaries, peritoneum, and ascites were analyzed and compared with initial clinical diagnoses and pathological results. Results: Among the six patients, five were initially clinically misdiagnosed as having primary ovarian cancer and underwent unnecessary total hysterectomy with bilateral salpingo-oophorectomy. One patient (case 6) was correctly diagnosed via percutaneous biopsy of the omentum and skin nodules, which confirmed metastatic ILC, thereby avoiding unnecessary gynecological surgery. Imaging findings: All six patients had bilateral ovarian masses, appearing as solid or cystic-solid lesions. Peritoneal changes were observed in four cases. Ascites was present in five cases. Laboratory findings showed marked variability in CA125 levels (normal in three cases, elevated in three cases). Immunohistochemistry confirmed breast origin in all cases (GATA3+, PAX8−, E-cadherin−). In case 6, after four cycles of chemotherapy (albumin-bound paclitaxel + carboplatin + bevacizumab), follow-up CT demonstrated significant reduction in ovarian masses and regression of peritoneal and omental lesions. Conclusions: Ovarian metastasis from ILC is easily misdiagnosed as primary ovarian cancer without histologic confirmation, leading to unnecessary radical surgery. However, as demonstrated in case 6, percutaneous biopsy of accessible metastatic sites (omentum, peritoneum, or skin nodules) can establish the correct diagnosis and guide systemic therapy, thereby avoiding unnecessary surgery. In case 6, the ILC ovarian metastasis showed a favorable response to chemotherapy, but this single-case finding requires cautious interpretation as ILC is generally considered less chemosensitive than invasive ductal carcinoma. In patients with a history of breast cancer or with suspected metastatic disease, ILC metastasis should be included in the differential diagnosis of ovarian masses.