Sigmoid colon metastasis from metaplastic breast carcinoma mimicking primary sigmoid colon cancer.

∗ Corresponding author at: Department of Nuclear Medicine, Keimyung University, School of Medicine, 194 Dongsan-Dong, Jung-Gu, Daegu 700-712, South Korea. E-mail address: [email protected] (H.W. Kim). (IHC) staining showed that the right breast cancer was negative for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER-2). The patient received adjuvant chemotherapy and radiotherapy. After two years, the patient developed intermittent hematochezia, and 18Ffluorodeoxyglucose (FDG) whole-body PET/CT scan was performed. The patient fasted for at least 6 h prior to the PET/CT examination and presented a blood glucose level of 97 mg/dL. Image acquisition was performed after 1 h after the intravenous injection of 370 MBq of 18F-FDG. The 18F-FDG PET/CT showed a hypermetabolic mass in the sigmoid colon (Fig. 1). The contrast-enhanced CT showed eccentric wall thickening of the distal sigmoid colon with an enhanced soft tissue density mass. The colonoscopy showed a protruding mass above the anal verge. The histopathological examination of the colonoscopic biopsy specimen revealed poorly differentiated carcinoma similar to that of the previous metaplastic breast carcinoma (Fig. 2). IHC staining demonstrated that the sigmoid colon cancer was negative for CK20, CK5/6, ER, PR, and HER-2, but positive for