1502 Colon Polyp as Rare Manifestation of Breast Cancer Metastasis

Abstract

INTRODUCTION: Breast cancer is the most common cancer in women worldwide. The leading cause of morbidity and mortality is due to distal metastasis. While metastasis to the brain, bones, lungs, liver and adrenal glands is usually seen, metastasis to the gastrointestinal tract is a rare, with colorectal involvement being an even rarer entity. We present a case of metastatic breast cancer presenting as a benign-appearing polyp on a colonoscopy. CASE DESCRIPTION/METHODS: A 56-year-old female with no significant past medical history except for schizophrenia presented with chief complaints of left breast mass with diffuse lymphadenopathy. Biopsy of the mass revealed invasive ductal carcinoma which was ER/PR (+) and HER2 (−) on immunohistology. PET/CT revealed diffuse bone metastasis. Contrast brain MRI showed isolated cerebellar brain lesion suggestive of neoplasm, likely secondary to the metastatic lesion. Patient was evaluated by Radiation oncology and radiation therapy started. During the hospital course, she was noted to have a gradual decrease in hemoglobin from 11 to 8.6 g/dl, while the reticulocyte count was normal. Although fecal occult blood testing was negative, Gastroenterology was consulted and EGD revealed gastritis and biopsies revealed inflammatory gastritis that was negative for H.Pylori. Colonoscopy revealed a 4 mm sessile polyp in the transverse colon (Figure 1). Biopsy of the polyp was consistent with adenocarcinoma which was ER/PR (+) (Figure 2) and HER2 (−) on immunohistology. Additional nuclear staining with breast markers including mammoglobin, and gross cystic disease fluid protein-15 was performed, and metastatic breast cancer was highly suggested. Unfortunately, due to the advanced nature of her breast cancer and poor overall nutritional status, the patient expired. DISCUSSION: In a review of cases reporting primary breast cancer with metastasis to the gastrointestinal tract, invasive lobular carcinoma of the breast is much more frequently represented. In our case presented above, the diagnosis was invasive ductal carcinoma of the breast with metastasis to the transverse colon. Diagnosis of metastasis to the colon may be difficult, as symptoms may be nonspecific. Due to this, patients with this entity often present late in disease progression. PET/CT often are non-contributory and do not show colonic metastasis. In conclusion, while gastrointestinal, especially colorectal, metastasis is rare, metastatic breast cancer can mimic a benign-appearing colon polyp on colonoscopy.