Amyloid tumor of the breast.

We diagnosed the mass as an amyloid tumor by an ultrasound-guided vacuum-assisted breast biopsy without resection. The patient had no systemic symptoms suspected systemic amyloidosis, and we diagnosed localized amyloidosis. An amyloid tumor of the breast may show findings suggestive of breast cancer. Pathological diagnosis before surgery is important to avoid excessive invasion. If deposits of nonstructural substances are observed by hematoxylin and eosin staining, Congo red staining should be added.