A Colonic Conundrum: Metastatic Infiltrating Lobular Carcinoma of the Breast to the Colon and Ovary

Abstract

Purpose: After lung cancer, breast cancer is the most common malignancy and second leading cause of cancer death in women. While breast cancer is usually diagnosed by a breast lump, the most common sign of metastatic breast cancer is weight loss. A 52-year old woman initially presented to her physician in 2004 with a left breast mass; she was diagnosed with a moderately differentiated infiltrating lobular carcinoma of the left breast (ILC), ER/PR positive and Her-2/neu negative. She underwent neoadjuvant chemotherapy, left modified radical mastectomy with negative lymph nodes, and adjuvant chemoradiation, as well as hormonal therapy for five years; during that time she had no evidence of recurrence. The next year, she presented to the GI clinic with two months of an intermittently palpable mass in the right lower quadrant. Physical exam revealed no palpable mass, and basic laboratories were normal. CT scan demonstrated marked distal small bowel and cecal thickening without obstruction and a left ovarian mass; these findings were not present two years prior. Pelvic ultrasound confirmed the ovarian mass. Colonoscopy revealed a circumferential, friable obstructive mass in the midascending colon; pathology had no evidence of malignancy with negative immunohistochemical (IHC) staining. Given the suspicion of malignancy and the obstructive nature of the mass, the patient underwent right hemicolectomy and bilateral salpingo-oopherectomy. Pathology demonstrated poorly differentiated adenocarcinoma positive for CK7, negative for CK20, and positive for mammaglobin; this constellation of findings was consistent with metastatic mammary carcinoma to the colon with transmural invasion to pericolonic adipose tissue, with 6/9 lymph nodes positive for metastasis. Left ovarian pathology demonstrated moderately differentiated adenocarcinoma with IHC staining also consistent with metastatic mammary carcinoma to the ovary. The most common sites of breast cancer metastasis include bone, liver, lung and brain. Metastases to the GI tract are less common, and colon metastases occur with far less frequency than small bowel metastases. In breast cancer metastases to the colon, ILC is less common than infiltrating ductal carcinoma (IDC), though that may be in part due to the lower prevalence of ILC. This unique case demonstrated ILC of the breast that years after therapy and no evidence of disease resulted in metastases to the colon and ovary. Breast cancer metastasis to the colon, although uncommon, should be considered in patients presenting with abdominal pain.