Residual pure intralymphatic carcinoma component only (lymphovascular tumor emboli without invasive carcinoma) after neoadjuvant chemotherapy is associated with poor outcome: Not pathologic complete response

Residual pure intralymphatic carcinoma (PIC) component only after neoadjuvant chemotherapy (NAC) is lymphovascular tumor emboli without invasive carcinoma and extremely rare form of residual tumor after NAC. Although several studies have been published, the prognostic influence of residual PIC component only had not been fully evaluated. This study aims to evaluate the clinicopathologic features and the prognostic value of residual PIC component only. We reviewed the 251 patients with no residual invasive carcinoma in breast after NAC and found 12 patients with residual PIC component only after NAC. Five cases were triple negative, 6 were HER2 positive, and 1 was estrogen receptor positive and HER2 negative. The extent of PIC component ranged from 0.18 to 50.00 mm. The detailed microscopic PIC component findings did not significantly correlate with regional lymph node metastasis, local recurrence, or distant metastasis (p > 0.05). In multivariate survival analysis, the presence of lymph node metastasis and pretreatment ki-67 labeling index more than 50 % was statistically associated with greater risk of relapse [Cox proportional hazards ratio (HR) = 3.236, 95 % confidence interval (CI), 1.461-7.280, p = 0.004; HR = 3.046, 95 % CI, 1.421-6.529, p = 0.004, respectively) and residual PIC component only tended to be associated with greater risk of relapse (HR = 2.378, 95 % CI, 0.853-6.631; p = 0.098), but not reached to statistically significance. In patients without lymph node metastasis, the presence of residual PIC component only was associated with worse disease -free survival (p = 0.004). Although the number of published studies still limited, residual residual PIC component only after NAC is associated with poor outcome, and it should not be considered as pathological complete response.