Axillary lymph node dissection is routinely used for all of the following conditions except:

A. 2-cm. pure comedo-type intraductal carcinoma.

DISCUSSION: Intraductal carcinoma is carcinoma in situ and does not metastasize to regional or distant sites. Lymph node dissection is not routinely required for a pure in situ cancer of the breast. In contrast, all of the other cancers listed above (infiltrating lobular, infiltrating ductal, and medullary carcinoma) are invasive malignancies that are capable of nodal and distant metastasis. Lymph node dissection is commonly recommended for these invasive malignancies. Intraductal lesions that have grown larger than 5 cm. are more apt to have become focally invasive. Since this invasive component might be missed histologically, many surgeons advocate selective use of axillary node dissection for large intraductal lesions, particularly high-grade tumors such as the comedo variant. However, a purely intraductal 2-cm. cancer would most likely be treated without performing node dissection.