Patient information

A 58-year-old female patient, with no significant family history of breast or ovarian cancer, was diagnosed with left-sided breast cancer in 2019 after presenting with a palpable breast lump and nipple retraction. A core needle biopsy confirmed invasive lobular carcinoma. Staging investigations, including contrast-enhanced computed tomography and bone scintigraphy, revealed no distant metastases at the time of diagnosis. She subsequently underwent a modified radical mastectomy with axillary clearance, with histopathological examination revealing a T3N3M0 tumor stage due to multiple positive axillary lymph nodes. Immunohistochemical studies indicated positivity for estrogen (ER) and progesterone receptors (PR), while human epidermal growth factor receptor (HER2) was negative ( Fig. 1 ). Subsequently, the patient received chemoradiotherapy and has since been maintained on hormonal therapy with an aromatase inhibitor, with regular follow-up.

(A) The invasive breast tumor consists of large tumor cells arranged individually and in ribbons, characterized by indistinct cytoplasmic borders, lightly eosinophilic cytoplasm, and large, pleomorphic, hyperchromatic nuclei with irregular outlines, within a desmoplastic stroma. (B) The breast’s in-situ component comprises expanded lobules with large, discohesive cells, featuring moderate lightly eosinophilic cytoplasm and uniform, round, hyperchromatic nuclei. (C-D) Both components show loss of membranous (E-cadherin staining. (E-F) Both components show nuclear staining of strong intensity for estrogen receptors. (G-H) Progesterone receptors show weak and patchy nuclear staining in the invasive component, while the in-situ component shows more diffuse and stronger staining. (I-J) The invasive component shows negative HER2/neu staining (score 0) while the in-situ component shows partial and weak membranous staining (score 1, also considered negative). (K-L) The invasive component has a high Ki-67 staining ratio (60%) while the in-situ component shows only scattered positive cells. [Hematoxylin and eosin (A-B), immunohistochemical antibodies with diaminobenzidine chromogen (C-L); original magnification x400 (A-L)].

Diagnostic approach

During routine follow-up, the patient underwent an abdominal ultrasound, which revealed a suspicious lesion in the left ovary, confirmed by a transvaginal ultrasound. Pelvic magnetic resonance imaging (MRI) scan revealed a 3.9 × 3.3 × 2.4 cm heterogeneously enhancing mass in the left ovary, suggestive of a malignant ovarian tumor, either metastatic or primary in origin ( Fig. 2 ). Fluorodeoxyglucose positron emission (FDG PET) scan findings were inconclusive, suggesting a benign nature of the lesion.

Pelvic MRI. (A) Axial T2 section shows a mass of heterogeneous intensity in the left ovary (yellow arrow) (B) Contrast-enhanced T1 fat suppression shows a heterogeneously enhancing mass (green arrow).

Laboratory investigations revealed normal levels of tumor markers, including carbohydrate antigen 125 (CA125) (12 U/mL, normal <35 U/mL), carbohydrate antigen 15-3 (CA 15-3) (18 U/mL, normal < 30 U/mL), and cancer embryonic antigen (CEA) (2.1 ng/mL, normal < 3.0 ng/mL). The lack of significant elevation in these tumor markers, typically seen in primary ovarian cancers, made differentiation between primary and metastatic disease more challenging.

Therapeutic approach

Given the indeterminate nature of the ovarian lesion and the patient’s history of hormone receptor-positive invasive lobular carcinoma, a laparoscopic hysterectomy with bilateral salpingo-oopherectomy was performed after detailed counseling and obtaining informed consent ( Fig. 3 ). Intraoperatively, no peritoneal or omental disease deposits were observed. The postoperative course was uneventful, and the patient recovered well without complications. Histopathological examination of the resected ovarian tissue revealed a left ovarian mass (measuring 4 cm) comprising metastatic lobular carcinoma of breast origin ( Fig. 4 ), confirmed through immunohistochemistry (IHC), establishing a clear link to the patient’s prior breast cancer. The Allred scoring system was used for receptor quantification, with a score of 6 for ER and PR. The score is a combination of staining intensity score (0 = none, 1 = weak, 2 = moderate, 3 = strong) and positive tumor cell percentage score (0 = none, 1 = <1%, 2 = 1-10%, 3 = 11-33%, 4 = 34-66%, 5 = >66%) ( Fig. 5 ). These findings established a definitive link to the patient’s prior breast cancer.

(A) Intraoperative view of the left ovarian tumor. (B) Panoramic view of the uterus with both ovaries and tubes.

Histology of the left ovarian mass reveals highly pleomorphic tumor cells that have hyperchromatic nuclei with visible nucleoli and abnormal mitotic figures (red arrow), heavily infiltrating as discohesive sheets and singly into a desmoplastic stroma (H&E, x200).

The tumor cells show strong cytoplasmic staining for CK7, negative staining for E-cadherin, positive nuclear staining for ER (score 6) and PR (score 6), and partial and weak cytoplasmic/membranous staining for Her-2 (score 1, considered negative).

Follow-up and outcome

Following confirmation of ovarian metastasis, the patient was referred to the medical oncologist, who initiated fulvestrant injections and palbociclib tablets as a part of a standard endocrine-based treatment regimen. She continues to undergo regular follow-ups, with no evidence of further metastatic progression to date.