KRT19 and metastatic malignant neoplasm in the lymph nodes: The pooling-OSNA® (one-step nucleic acid amplification) method, based on the RT-LAMP (reverse transcription loop-mediated isothermal amplification) of cytokeratin 19 (CK19) mRNA for the detection of lymph node metastases, surpassing the current performance of conventional morphological analysis with H&E.