EVALUATION OF PANCYTOKERATIN IMMUNOHISTOCHEMISTRY FOR DETECTING OCCULT LYMPH NODE METASTASIS IN EPITHELIAL MALIGNANCIES

Abstract

Background: Lymph node metastasis is a critical prognostic factor in epithelial malignancies. Routine hematoxylin and eosin (H&E) staining may miss occult deposits such as micrometastases and isolated tumor cells, leading to understaging. Immunohistochemistry using pancytokeratin (PANCK) can improve detection.

Aim: To evaluate the utility of PANCK immunohistochemistry in detecting occult lymph node metastasis in histologically negative nodes and its impact on TNM staging.

Materials and Methods: A cross-sectional study was conducted from June 2024 to March 2026 on 530 lymph nodes from resected epithelial malignancies. All nodes were examined by H&E and PANCK (AE1/AE3) immunohistochemistry. Clinicopathological parameters and TNM staging were assessed.

Results: PANCK identified occult metastases in 5 of 496 H&E-negative nodes (1%), increasing sensitivity from 87.2% to nearly 100% (p < 0.0001). Additional positivity was highest in uterine (9.5%) and colorectal (2.4%) cancers, with minimal gain in breast carcinoma (0.5%). PANCK was more useful in low- and intermediate-grade tumors. TNM staging was upgraded in 3 cases (8.6%).

Conclusion: PANCK immunohistochemistry significantly improves detection of occult nodal metastases, enhances diagnostic sensitivity, refines pathological staging, and may guide adjuvant therapy in selected epithelial malignancies.