Atypical medullary carcinoma of the breast with cartilaginous metaplasia in a patient with a BRCA1 germline mutation

We examined a 34-year-old premenopausal woman who had noticed a left-breast lump a month previously. She had no past history of malignancies but had a family history of breast and ovarian cancers. Her mother had suffered from ovarian cancer when aged 47 years and had died of the disease at age 52, T he younger two of the patient's four aunts had developed breast cancer when they were 37 and 48 years old. A physical examination showed an ill-define d mass, 1.5 cm in diameter, located in the upper outer quadrant of the pati ent's left breast, Mammography revealed diffuse microcalcification in both breasts but ultrasonography revealed an irregular tumorous lesion only in t he left breast. Aspiration breast cytology revealed adenocarcinoma of the l eft breast, Modified radical mastectomy of the left breast and excision of a biopsy specimen from the right breast were carried out simultaneously. Hi stopathologically the left-breast tumor was an atypical medullary carcinoma with cartilaginous metaplasia, of histological grade 3, and the right-brea st specimen showed fibrocystic changes with atypical ductal hyperplasia. Es trogen receptors were positive, but progesterone receptor was not detected on the tumor cells, which were immunopositive for nuclear p53 although c-er bB-2 overexpression was not observed. A nonsense germline mutation of the B RCA1 gene (exon5) was detected, The patient has been well since the operati on (10 months). These findings may provide useful information about the car cinogenesis and biological behavior of BRCA1-associated breast cancers.