Clinical implications of margin involvement by pleomorphic lobular carcinoma in situ

The appropriate treatment for patients with pleomorphic lobular carcinoma in situ (PLCIS) is unknown. When diagnosed on core biopsy, excision is recommended; however, management of PLCIS when it involves margins has not been addressed.

To evaluate the significance of PLCIS that is located close to, or at, a resection margin.

We identified 26 patients with resection specimens containing PLCIS, all of whom were offered chemoprevention and radiation therapy. The margin status in these patients was subdivided as PLCIS cells at the margin without obvious truncation of lesion; PLCIS less than or equal to 1 mm from, but not involving, the margin; PLCIS 1.1 to 2 mm from the margin; and PLCIS at least 2.1 mm from the margin.

Patient age ranged from 35 to 76 years (mean, 58 years), and length of follow-up ranged from 4 to 108 months (mean, 46 months). Six of the 26 patients (23%) received chemoprevention, 4 of 26 patients (15%) received radiation therapy, and 6 of 26 patients (23%) received both. The remaining 10 patients received no further therapy. Pleomorphic lobular carcinoma in situ was at the margin in 6 of the 26 cases (23%), 1 mm from the margin in 7 of 26 cases (27%), 1.1 to 2 mm from the margin in 4 of 26 cases (15%), and was at least 2.1 mm from the margin in 9 of 26 cases (35%). In 1 of the 26 patients, recurrent PLCIS was identified 18 months after initial surgery, for an overall recurrence rate of 3.8%. All other patients were clinically and radiologically free of disease at last follow-up.

This is the first series, to our knowledge, that evaluates margin status in patients with PLCIS and documents recurrence. Recurrent PLCIS was identified at a rate similar to low- or intermediate-grade ductal carcinoma in situ. Therefore, known methods of local control, including surgical excision with negative margins (2 mm), may be the appropriate treatment in these patients.