Immediate and ipsilateral recurrence rates and treatment recommendations for patients with pleomorphic and florid lobular carcinoma in situ.

Background: Follow-up data are limited regarding the natural history of patients diagnosed with pleomorphic lobular carcinoma in situ (PLCIS) and florid lobular carcinoma in situ (FLCIS).

Methods: This retrospective study identified patients with PLCIS and FLCIS. Clinicopathologic findings were evaluated. Patients with concurrently diagnosed ipsilateral breast cancer or ductal carcinoma in situ were excluded. The immediate and delayed risk of developing breast cancer was calculated.

Results: All 45 patients were female, and the median age was 61 years. The most common imaging finding was suspicious calcifications on screening mammogram in 84.4%. The histology was PLCIS in 75.6% of cases (34/45), FLCIS in 11.1% (5/45), and a combination of variant types in 13% (6/45). Forty-four patients underwent surgery to include wide local excision in 84% (37/44) and mastectomy in 15.9% (7/44). One patient (2.3%) had concurrent DCIS on excision and ten patients (22.7%) had diagnoses upgraded to invasive carcinoma on excision, the majority being T1a (70%) and the remainder T1b (30%). These aforementioned patients were excluded from further outcome analysis. There were four patients (8.8%) with PLCIS who developed ipsilateral cancers in the same quadrant; of which two were local and two were local regional occurring 135, 106, 89, and 60 months after the initial diagnosis. All four patients had < 2 mm margins after initial surgery (p < 0.05).

Conclusions: There is both an immediate (24.4%) and delayed (8.8%) risk of breast cancer in patients diagnosed with PLCIS and FLCIS. Our data support excision to 2 mm margin and maintenance of long-term follow-up.