Metastatic breast carcinoma uncovered in an otherwise unremarkable “random colon biopsy”

Breast cancer is one of the most devastating cancers afflicting women, being a main cause of cancer related death. Approximately 50% of these patients have developed regional or distant metastases at the time of diagnosis; hence, an early diagnosis and surgery with indicated neoadjuvant therapy are crucial in eradicating this disease and improving patient survival. A significant percentage of patients, even after initial satisfactory tumor removal, still face the threat of metastatic diseases which could plague a wide spectrum of body sites such as bones, lungs, central nervous system, liver and gastrointestinal tract (mostly upper gastrointestinal locations). Colonic and anorectal involvement by metastatic breast cancer has been less frequently reported in disseminated diseases. Typically, metastatic disease presents as a mass, enteric stenosis, or obstruction. Rare cases, however, may not form an endoscopically or radiologically recognizable lesion, and thus could be overlooked. Here we report a unique case of random colon biopsies in a patient presenting with epigastric pain, whose stomach biopsy showed Helicobacter pylori-associated chronic active gastritis. No colonoscopic lesion was present; however, microscopic examination of the “random biopsy” revealed scattered single and small clusters of tumor cells involving the lamina propria of the colonic mucosa, morphologically and immunophenotypically consistent with metastatic disease from breast carcinoma. The clinical presentation and histopathology of the case were reviewed and compared with limited cases reported in the literature. We conclude that high levels of suspicion and alertness are essential to identify occult microscopic gastrointestinal metastatic breast cancer in the absence of a grossly appreciable lesion.