Cytokeratin-positive cells in sentinel lymph nodes in breast cancer are not random events

BACKGROUND. The incidence of immunohistochemistry (IHC)-detected epithelial cell displacement in sentinel lymph node (SLN) biopsy is unknown. In the current study, we address this question by examining the pattern of SLN involvement in patients undergoing prophylactic mastectomy (PM) at Memorial Sloan-Kettering Cancer Center (New York, NY). METHODS. Between January 1999 and January 2003, 5275 patients underwent SLN biopsy. Unilateral or bilateral PM with SLN biopsy was performed in 143 (2.7%) patients, representing 163 PM cases. RESULTS. Occult carcinoma was identified,in 13 of 163 (8.0%) PM specimens. Two patients with occult invasive carcinoma had positive SLNs (hematoxylin and eosin). In the remaining 150 PM cases without occult carcinoma (130 patients), 89% underwent IHC analysis of the SLNs. Of these 130 patients, 43 (33%) had one or more prior biopsies in their "cancer-free" breast, a median of 43 days (range, 3-314 days) before PM. A total of 310 SLNs were examined by IHC (mean, 2.3 lymph nodes per PM case). Only 1 of 130 (0.8%) patients without occult carcinoma had an IHC-positive SLN. This patient had Stage IIIC carcinoma of the contralateral breast. IHC-positive SLNs were not identified in any of the 43 patients with a history of prior biopsy. Therefore, only 1 IHC-positive SLN was detected in 310 (0.3%) lymph nodes examined. CONCLUSIONS. IHC-positive cells in SLNs are rare in the absence of cancer and are not the result of previous breast instrumentation. Although the prognostic significance of IHC-positive cells remains controversial, the current study suggests that they are not random events. (C) 2004 American Cancer Society.