SUN-935 Invasive Neuroendocrine Breast Carcinoma Presenting as Liver Metastases

Abstract

Introduction: Primary neuroendocrine carcinoma of the breast is rare and must be differentiated from metastatic neuroendocrine carcinoma from the gastrointestinal tract. Clinical Case: A 66-year-old white female presented to the outpatient clinic complaining of abdominal fullness with unintentional weight loss of over 30 pounds over 3 months. She had no nausea, vomiting, diarrhea, or constipation. During initial evaluation, she had hepatomegaly with the liver edge palpable 4 cm below the costal margin. Laboratory studies are within normal limits except for elevated alkaline phosphatase at 369 U/L (n<130 U/L). A CT scan of the abdomen and pelvis with contrast showed extensive malignant lesions involving the liver consistent with prior hepatocellular carcinoma versus metastatic disease. Patient had a colonoscopy and esophagogastroduodenoscopy in an attempt to identify a primary gastrointestinal malignancy, but both studies were unremarkable. Ultrasound guided biopsy of the liver masses revealed malignant cells with morphologic features that were suggestive of metastatic neuroendocrine carcinoma. The patient was started on monthly intramuscular octreotide 30 mg. She had a Gallium-68 dotatate scan showing increased uptake in the area of several large heterogeneous necrotic tumors throughout the liver, and in the left sixth posterolateral rib. The maximum uptake was noted in a 3.7 cm x 3.5 cm ovoid mass in the right breast. The patient admitted to noticing a mass in her right breast which decreased in size after her initial dose of octreotide. She had not had a mammogram in several years and refused a breast exam during initial evaluation. The patient was sent for mammography and ultrasound as well as for biopsy of the breast lesion. Results of the breast biopsy showed intermediate grade neuroendocrine tumor of the breast. The patient underwent right total mastectomy with lymph node staging, and intraoperative pathology identified neuroendocrine carcinoma of intermediate grade in the right breast and right axillary lymph nodes, and macrometastatic carcinoma in a right axillary tail lymph node. Immunohistochemistry showed the malignant cells were chromogranin and synaptophysin positive. They were also estrogen receptor positive. The cells were negative for progesterone receptor and human epidermal growth factor receptor 2. The patient follows up regularly with oncology and continues to receive monthly doses of octreotide. She was also started on exemestane and had Yittrium-90 radioembolization of liver metastases. Conclusion: Patients with neuroendocrine carcinoma of the breast rarely present with clinical conditions related to hormonal hypersecretion as in neuroendocrine carcinoma of the GI tract but respond to treatment with somatostatin analogs.