Breast Carcinoma Presentation as Acute Small Intestinal Obstruction: Carcinoma of Unknown Primary

Cancer of unknown primary (CUP) is a relatively common clinical entity accounting for 4 to 5% of cancers (Scoggins et al., The American Surgeon 65(1):1, 1999). Adenocarcinoma and undifferentiated carcinomas account for 75% of CUPs. The diagnosis of CUP is mainly done by immunohistochemistry (IHC). Some of the important biomarkers used for the differentiation of the tumor lineage in CUP for breast primary are GATA3, ERM GCDFP-15, TFF1, and MGB (Thomas et al., Eur J Nucl Med Mol Imaging 37(3):635–644, 2010 Mar). We highlight the importance of mammaglobin (MGB) as a diagnostic marker in metastatic breast carcinoma. We present a 55-year-old lady who had presented with acute small bowel obstruction. Computer tomography (CECT) had revealed a stricture involving the mid ileum. Laparotomy with resection and anastomosis was done. The histology was a poorly differentiated adenocarcinoma. Six months later, she had presented with a lump in the right breast and trucut histology had shown an invasive lobular carcinoma. IHC was positive for estrogen (ER), progesterone (PR), and mammaglobin receptor. With a high index of suspicion, the previously reported poorly differentiated adenocarcinoma of the small bowel was reviewed and IHC for mammaglobin was positive. This was consistent with a metastatic carcinoma of the small bowel with the primary being breast. She is on tamoxifen and doing well on short follow-up.