Metastases to the breast.

Metastases to the breast are uncommon, with about 250 cases reported from clinical and autopsy series. The mammographic findings in 16 new cases revealed a spectrum of changes that included solitary or multiple lesions, well demarcated or poorly marginated masses, and diffuse involvement of skin or parenchyma or both. Diffuse disease was seen more frequently in this series (4/16), at times simulating inflammatory breast cancer. Although diagnosis of a primary malignancy usually preceded detection of the breast lesion, 40% (6/16) had no history of malignancy. Prognosis remains poor; however, it has improved in the lymphoma-leukemia group due to improved immunotherapeutic and chemotherapeutic regimens. The clinical, radiologic, and pathologic features are discussed. Some of the lesions encountered can be confused with a primary breast malignancy or a benign lesion, necessitating prompt and accurate biopsy to preclude unnecessary major surgery and to improve survival in cancers amenable to current therapy.