Resection margin status in lumpectomy specimens of infiltrating lobular carcinoma

To study the status of resection margins in specimens from patients with infiltrating lobular carcinoma (ILC) treated with lumpectomy.

Sixty-six consecutive cases of ILC were compared with the same number of consecutive cases of infiltrating ductal carcinoma (IDC). All cases were treated with lumpectomy.

ILCs were divided into 42 cases of typical ILC, 15 variants of ILC (alveolar or solid types) and 9 cases of mixed ILC and IDC. These groups were associated with positive or close resection margins in 22 (52%), 5 (33%) and 3 (33%) cases, respectively. For the group of IDC with partial mastectomies, matched for patient's age and tumor size, positive or close resection margins were observed in 26%. ILCs, measuring less than 2 cm in greatest diameter and having low nuclear grade, had rates of positive or close margins comparable with those of IDC. Typical ILCs, measuring more than 2 cm in diameter, had rates of positive or close margins of 70%. All cases with a positive extensive intraductal component had positive margins. Furthermore, in all types of ILC, tumors with a high nuclear grade tended to be associated with a high rate of positive margins.

The status of resection margins in lumpectomy specimens for infiltrating lobular carcinoma is related to the extensive intraductal component status, tumor size and grade, and the presence of variants of ILC or mixed ILC and IDC. Most of these factors can be determined preoperatively by mammography and histopathological evaluation of breast core biopsies, therefore, aiding in planning the surgical strategy of mastectomy.