The reliability and accuracy of intraoperative imprint cytology of sentinel lymph nodes in breast cancer.

OBJECTIVE: Sentinel lymph node (SLN) biopsy is a new component of the surgical treatment of breast cancer that accurately predicts axillary status. In this study the authors evaluated the accuracy of intraoperative imprint cytology (IC) in comparison with definitive histologic evaluation of SLN in breast cancer patients.
METHODS: A total 413 women with breast carcinoma and clinically negative axillary nodes underwent breast surgery and SLN biopsy. Mapping of SLN involved injection of (99m)Technecium labelled human albumin nanocolloid particles and Patent Blue dye. At the Department of Pathology, SLNs were bisected along its major axis. Both halves were imprinted 2-4 times on the slides and immediate staining with Hemacolor (Merck Germany) was performed for intraoperative examination. Imprint node negative women underwent no further surgery, while node positive women proceeded to full axillary clearance. Histological analysis of the SLN involved serial sectioning of the whole node with H&E and immunostaining for cytokeratin.
RESULTS: Definitive histology revealed metastases (pN+) in 159/413 patients (38.5%): 69 (16.7%) macro metastases, 57 (13.8%) micro metastases, and 33 (8%) women with only isolated IHC positive cells or positive cell groups smaller than 0.2 mm (pNO sn+). The other 254 women had negative SLN biopsy. Imprint cytology detected 54/69 macro metastases, and 4/57 micro metastases. In the group with negative SLN (254), 2 cases were ''false positives''.
CONCLUSIONS: Imprint of SLN biopsy can identify a negative axilla with high accuracy (specificity 99.2%). Overall sensitivity is only 36.5%, but macrometastases are detected in 77% which is important for performing ALDN in one session with operation of primary tumour.