Detection of micro-metastases by serial sectioning and immuno-histochemical validation of sentinel nodes in patients with breast carcinoma

Abstract

Background Examination of sentinel lymph node (SLN) biopsy can give accurate nodal staging for breast cancer and assist in the management of patients. Serial sectioning and immuno-histochemical (IHC) staining of SLN can improve detection of micro-metastases. Methods Twenty-five patients with clinically node-negative breast cancer were recruited. A combination of radiotracer and blue-dye were used for identification of SLN. The nodes were thinly sliced and embedded. Serial sectioning and immuno-histochemical staining against AE1/3 were done if initial H&E sections were negative. Results Three cases (12%) had no tumour at initial H&E sections but tumour was found at serial levels and with IHC validation. These were micro-metastases of less than 2 mm diameter. Four other cases with macro-metastases were found at initial H&E sections of the SLN. Three false negative cases had axillary nodal (ALN) metastases with no tumour in the SLN despite levelling and IHC staining. Discussion and conclusion Thin slicing of tissue and serial sectioning improved the detection of micro-metastases. However, immuno-histochemical validation did not additionally increase the sensitivity of detection. The presence of ALN metastases without SLN involvement could be due to discontinuous or skip metastases to non-sentinel nodes or poor technique resulting in missed detection of the SLN.