A case of invasive lobular carcinoma of the breast first manifesting with duodenal obstruction.

Lobular carcinoma of the breast presents with various clinical manifestations. Lobular carcinoma comprises about one fifth of cases of ductal carcinoma. Intestinal metastasis is dominant in cases of lobular carcinoma. Without a prior diagnosis of lobular carcinoma of the breast, the diagnosis of intestinal metastasis from breast cancer is difficult. A 52-year-old women underwent duodenogastrectomy for duodenal cancer. About 18 months later, she underwent mastectomy for lobular carcinoma of the breast. The duodenal cancer consisted mainly of malignant cells invading the submucosa that were identical to those in the breast. Immunohistochemical assays for estrogen receptor also confirmed breast cancer metastasis. Duodenal obstruction was the first sign of isolated metastatic lobular carcinoma of the breast in this case. The characteristic metastatic pattern of lobular carcinoma, which differs from that of ductal carcinoma, should be kept in mind to ensue proper diagnosis. Preceding breast surgery for lobular carcinoma should prompt investigation based on the typical metastatic pattern.