Author(s): Stephen Sixto Siguan, M.D., F.P.C.S.; Lloyd Nario Bordeos, M.D. and Saleshe Tracy Anne Baking-Fernandez, M.D., F.P.C.S.
1) To determine the accuracy rate of sentinel lymph node biopsy (SLNB) by comparing frozen section (FS) with permanent formalin processed specimen by hematoxylin and eosin (H&E) staining; 2) To correlate with axillary lymph node dissection (ALND) histopathology results for those with positive SLNB.
This was a retrospective study on all breast cancer patients who underwent SLNB using methylene blue dye. The number of SLN harvested, number of lymph nodes confirmed on frozen section, frozen section result, number of SLN confirmed on paraffin block H&E, result of H&E. If frozen section of SLN was positive for metastasis, further data on the axillary lymph nodes harvested and its final H&E result were noted. The accuracy rate was determined. Whenever a discordance of FS and H&E findings occurred, the interpreting pathologists were interviewed for the cause.
A total of 34 SLNB procedures were performed. There were 24 SLNBs that turned out negative on frozen section while 10 were positive for metastasis and underwent further ALND. Three of the 24 negative SLNBs turned out to be positive (false negative rate of 12.5%). Out of the 10 positive SLNBs, 1 turned out to be negative (false positive rate of 10%). Only 6 of the 10 patients with (+) SLNB had more positive nodes harvested upon further ALND. The accuracy rate of SLNB on frozen section was 88%, with sensitivity and specificity of 90% and 87.5% respectively. There were 5 pathologists involved in the interpretations of the SLNB, and in 76% the pathologist interpreting the FS was different from the one interpreting the permanent specimen H&E. The reasons for discordance between frozen section and final H&E reading were inter-reader variability and tissue sampling limitation during frozen section.
The accuracy of frozen section in SLNB procedure is 88%.
Key words: Sentinel lymph node biopsy, axillary lymph node dissection, breast cancer