Metastatic Lobular Carcinoma of the Breast Presenting with Small Bowel Metastases: Case Report and Literature Review

Introduction: Invasive lobular carcinoma (ILC) is the second most common histologic type of breast cancer, representing 5% to 15% of invasive tumors. ILC tends to spread to bones, lungs, central nervous system, reproductive organs, and the gastrointestinal tract (GI tract). The most commonly affected organs in the GI tract are the stomach, small intestine, followed by colon and rectum. Case presentation: A 78-year-old woman who was referred to our institution after having a bowel obstruction that required a diagnostic laparoscopy where they identified an obstructing ulcerative lesion in the distal ileum that was managed with a segmental bowel resection. Pathology report showed an invasive lobular breast carcinoma that occluded 90% of the bowel lumen. A PET/CT scan revealed a left breast tumor with increased metabolism. The patient was staged as a clinical cT4b, cN0, cM1 left breast invasive lobular carcinoma (ER/PgR positive, HER-2 negative). She was managed with endocrine therapy with Letrozole (an eight-week course). A follow-up PET/CT showed a peritoneal hypermetabolic nodule adjacent to the previous ileal anastomosis. The lesion decreased in size and metabolic activity. In a multidisciplinary fashion, the endocrine therapy was extended for another three months. Another follow-up PET/CT scan was performed three months after the identification of the peritoneal implant that showed that the nodule increased in size and in metabolism. The lesion continued to decrease significantly in size and became metabolically inactivity. Due to the good breast response and the possibility that the ileal nodule could be a granuloma, she underwent an exploratory laparoscopy with excision of the peritoneal nodule, and a modified left radical mastectomy with immediate breast reconstruction (complex wound closure). The final pathology report of the nodule was negative for malignancy. She continued on endocrine therapy and underwent whole breast irradiation four weeks after the operation. Currently, she is free of disease with no evidence of local, regional, or distant recurrence, and she is still on endocrine therapy. Discussion: The time interval between primary breast cancer and gastrointestinal involvement may range from synchronous presentation to as long as 30 years. The clinical manifestations in GI lobular breast cancer metastasis may range from non-specific complaints to acute GI symptoms, such as a bowel obstruction. There are multiple controversies in the management of ILC. Systemic treatment should be initiated as soon as possible. Indications for postmastectomy radiotherapy are also controversial, given the propensity for multifocal/multicentric tumors and late recurrences, sometimes in atypical locations. Five years of postoperative adjuvant hormonal therapy is an option for women with poor prognosis. Remissions are observed in 32% to 53% of patients. Conclusion: Metastatic lobular carcinoma of the breast has a wide range of clinical presentations. Patients with a history of breast cancer who present with new GI tumors should have these lesions evaluated for evidence of metastasis through histopathologic and immunohistochemical analysis, this will allow for appropriate management. Currently, breast cancer management involves a multidisciplinary approach including surgery, radiotherapy, and systemic medical therapy, and the treatment must be tailored to the patient’s needs.