Abstract Breast carcinoma is the most frequently diagnosed cancer in women. In up to 30%, distant metastases will occur; however, ileocecal metastases are rare. Although there have been cases reported that demonstrate ileocecal metastases of breast carcinoma, PET/CT-negative cases have never been described. We present a patient with a small bowel obstruction, preoperatively complicated by pulmonary embolisms. The patient underwent placement of an inferior vena cava filter followed by hemicolectomy. Pathological examination revealed ileocecal lobular breast carcinoma metastases and adjacent peritoneal carcinomatosis, which had shown no intestinal 18FDG uptake 7 weeks prior to presentation. Subsequently, symptoms of metastases and the paraneoplastic syndrome progressed, and the patient was referred to the medical oncologist for palliative therapy. Although uncommon, physicians should be aware of potential presence of 18FDG-negative gastrointestinal metastases of breast cancer.