Micrometastasis in axillary lymph node in breast cancer: immunohistochemistry versus hematoxylin and eosin detection

INTRODUCTION: The methods of detection and prognostic significance of micrometastasis (Mic-Met) are still controversial in the literature. AIMS: The aim of our study was to compare micrometastasis detection of invasive mammary carcinomas (IMC) in axillary lymph nodes using a second review (double review) of hematoxylin and eosin (HE) stained slides using immunohistochemistry (IHC) and the impact of micrometastasis detection in re-staging patients. MATERIAL AND METHODS: We studied 190 cases of IMC with no axillary metastasis described in the original reports. We reviewed the available HE stained slides of lymph nodes. New sections were obtained from archived paraffin blocks and were submitted for IHC using the pancytokeratin antibody AE1/AE3 and the streptavidin biotin peroxidase method. RESULTS: We reviewed 2868 lymph nodes stained by HE (mean = 15.1 lymph nodes/patient) and 2.444 lymph nodes stained by IHC (mean = 12.9 lymph nodes/patient). Micrometastasis were detected in 28/190 cases, (by HE in 14/190 cases, 7.4%, and by IHC in 25/190 cases, 13.2%). The second review of the HE stained slides showed good specificity (98.2%), but low sensitivity (44%), when compared to IHC (considered the gold standard). Conclusions: The detection of micrometastasis was better using immunohistochemistry than second review, and changed the stage of 28 patients (14.7%).

Micrometastasis; Breast; Carcinoma; Immunohistochemistry; Hematoxylin-eosin

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