[ Monash University ]

Museum of Pathology



Clinical History

The patient was a 60 year old woman who presented with a painless lump in the left breast which she had first noticed 4 years earlier. The lump had gradually increased in size. There had been no nipple discharge and she was otherwise well. ,On examination, the nipple was markedly retracted and deep to the nipple there was a hard mass which was fixed to the underlying pectoral muscle. Hard lymph nodes were palpable in the left axilla but the chest was clear and the liver was not enlarged. A radical mastectomy was performed followed by post-operative deep x-ray therapy.


The specimen is a breast sliced vertically through the nipple down to and including a portion of the pectoralis major. Beneath the inverted retracted nipple there is a pale tumour 3 cm in diameter which has an irregular border due to strands of tumour extending into the adjacent fat. The tumour has infiltrated the pectoralis major and is tethered to the muscle. This is an example of an infiltrating carcinoma of the breast. Axillary lymph nodes were involved.


Carcinoma of the breast arises in the ductal or glandular epithelium of the breast lobule and excretory duct system. The tumour commences as a proliferation of atypical epithelial cells which eventually fills and expands the lumen of the duct. Carcinoma confined within the basement membrane of a duct is called intra-duct carcinoma. When the tumour cells eventually infiltrate through the basement membrane and extend into the adjacent stroma, the lesion is called infiltrating carcinoma of the breast. Infiltrating carcinoma is of 2 main types: (i) infiltrating ductal carcinoma, which is believed to arise in the ductal epithelium. This is the common form of infiltrating carcinoma of breast (90% of (ii) infiltrating lobular carcinoma, which is believed by some authors to arise in the ductules (secretory acini) of the lobule. This is less common (5-10% of cases of infiltrating breast carcinoma). These two malignant tumours have slightly different histological appearances. The distinction is of clinical significance because lobular carcinoma is more likely to be multifocal and bilateral thaductal carcinoma.