Clinical History:

A 63-year-old woman who was born and lived in the U.S. all her life underwent mammography screening after her physician palpated a mass in the left breast that had irregular margins and seemed fixed to the overlying skin, which had a rough, orange-red appearance. Both the patient's mother and a maternal aunt died of breast cancer. The mammogram revealed a poorly defined mass in the left breast. A left mastectomy with axillary lymph node sampling was performed.

Beneath the skin, the breast and adipose tissue are massively and irregularly infiltrated by atypical epithelial cells, many of which do not have convincing evidence for gland formation. This tumor is arising in the breast tissue and invades toward the epidermis. Note the multiple discrete round spaces, either empty or filled with plugs of neoplastic cells. These spaces are subepidermal lymphatics invaded by the cancer, causing lymphatic distention, giving the overlying skin an "orange peel" appearance on physical examination. Metastatic carcinoma was found in the axillary nodes.

The patient's 34-year-old daughter, worried about cancer affecting her, sees her physician, and a small lump is palpable. This is excised.

Questions:

1. What is the significance of the history of breast cancer in the family?

A family history of breast cancer, particularly on the maternal side (mother, aunt, sister) suggests an increased risk of breast cancer for the patient. The earlier the age of onset, the more likely a specific genetic abnormality, such as a BRCA1 or BRCA2 mutation, is present and the greater the risk for other family members.

2. What is the degree of differentiation?

This neoplasm is moderately differentiated. The neoplastic cells are attempting to make ill-defined ducts. This neoplasm is thus termed an infiltrating ductal carcinoma of breast.

3. What methods are available for diagnosis of the mammographic lesion to determine if mastectomy should be performed?

Needle aspiration biopsy can be done for cytologic diagnosis. An excisional biopsy will yield more tissue for definitive diagnosis and for hormone receptor assay if malignant.

4. What is the most likely diagnosis for the daughter's breast lesion?

This small mass proved to be a fibroadenoma, a benign neoplasm that is relatively common in the breast. Overall, most breast "lumps" turn out to be benign, but a malignancy must be ruled out.