Lobular carcinoma of the breast with gastrointestinal metastasis.

We present the case of a 74-year-old woman with metastatic lobular carcinoma with an occult breast primary presenting as a suspected ampullary tumor due to its ampullary metastasis. The patient's clinical presentation is of interest in two aspects. First, lobular carcinoma of the breast metastatic to the ampulla is extremely rare. Second, in the absence of a detectable primary lesion, prior history of malignancy, or distinguishing clinical, radiological, and endoscopic features, histopathological assessments are pivotal for arriving at the appropriate diagnosis and for optimizing treatment.