Diagnostic Accuracy of Imprint Cytology in Sentinel Lymph Node Evaluation of Breast Cancer Patients in a Resource-Limited Setting

Abstract Background Sentinel lymph node biopsy is a standard technique for staging of breast node-negative axilla in patients undergoing a mastectomy or breast-conserving surgery. Evidence on touch imprint cytology performance from resource-limited settings, which depends solely on a single technique, is comparatively limited. The study aimed to test the sensitivity, specificity, and accuracy of touch imprint cytology and compare it with final histopathology as a reference standard. Methods The study was a retrospective observational study among 88 breast cancer patients who underwent mastectomy or breast-conserving surgery over two years. Following intraoperative imprint cytology of sentinel lymph nodes, results were communicated to the operating surgeon, who then proceeded with definitive surgery, lumpectomy or mastectomy with or without axillary dissection. Excised specimens were subsequently sent for formal histopathological analysis. A set of diagnostic performance indicators, such as sensitivity, specificity, positive predictive value, negative predictive value, and general accuracy, was determined. Results The sensitivity and specificity were found to be 93.8% and 75.0%, respectively. The median number of lymph nodes evaluated per case was 3(IQR: 2, range: 1 to 7). The positive and negative predictive values were 45.5% and 98.2%, respectively; overall accuracy was 78.4%, and all estimates were given with 95% confidence limits, highlighting the reliability of the findings. Conclusions Touch imprint cytology demonstrated high sensitivity and a clinically meaningful NPV value in this study, supporting its use as a primary intraoperative technique where frozen sections were unavailable. Nonetheless, false negative results remain a concern, as they can cause under-treatment and require completion of axillary dissection.