[Breast cancer metastasis to the colon]

A 69-year-old woman was admitted with diarrhoea, anaemia and elevated C-reactive protein. She was diagnosed with metastases of a carcinoma to the colon; the immunohistochemical profile made lobular breast cancer the most likely primary tumour. But despite thorough examination, such tumour was never found. Twenty-two years earlier, the patient underwent surgery for a benign breast tumour. The benign diagnosis was confirmed in new slides from the then removed tissue. Metastases from breast cancer to the colon are rare, and a primary tumour is usually found. In this case report, however, no primary tumour was found.