Metastatic invasive lobular breast cancer with stomach, ovarian, peritoneal, rectal, and jejunal spread

What happened, in summary

This 43-year-old Iranian woman had been treated for Hodgkin’s lymphoma during adolescence. In 2015, she developed a right breast mass and right axillary lymph-node enlargement. Biopsy showed grade 2 invasive lobular breast carcinoma that was strongly ER-positive and PR-positive, HER2-negative, with Ki-67 about 15-16%. Baseline staging showed no distant metastasis. She received neoadjuvant doxorubicin and cyclophosphamide followed by paclitaxel, then underwent right modified radical mastectomy. Pathology showed multifocal invasive lobular carcinoma, lymphovascular and perineural invasion, 2 involved axillary nodes, and additional tumor deposits in axillary fat. She then received chest-wall and regional-node radiotherapy, 50 Gy in 25 fractions, followed by tamoxifen and ovarian suppression with triptorelin. From 2015 to 2021, she remained clinically stable. In early 2021, CA 15-3 rose steadily, but biopsies of a mildly PET-avid cervical lymph node were reactive. Endocrine therapy was changed to letrozole with continued ovarian suppression. About 3 months later, she developed dyspepsia and vague upper-abdominal discomfort. PET-CT showed mild diffuse gastric-wall uptake, and endoscopy found patchy nodular redness. Gastric biopsies confirmed metastatic lobular breast cancer: pancytokeratin-positive, GATA3-positive, ER-positive, PR-positive, HER2-negative, and beta-catenin-negative. She received paclitaxel/gemcitabine, then docetaxel/gemcitabine, followed by maintenance palbociclib with fulvestrant and later exemestane/palbociclib. In 2023, bilateral salpingo-oophorectomy for ovarian suppression unexpectedly found metastases in both ovaries, with malignant cells in peritoneal washings. Later, rectal biopsies confirmed metastasis after constipation and bleeding, and jejunal involvement caused partial small-bowel obstruction in 2025. She continued active systemic and supportive care. Her course showed the hidden, diffuse spread pattern that can occur with invasive lobular carcinoma.