KRT19 and head and neck squamous cell carcinoma: Goda et al. analysed 213 HNSCC lymph nodes with CK19 OSNA and suggested an overall accuracy of 94% per node and 94% per patient.20 Matsuzuka et al. found a NPV of 95.9% in HNSCC.21 Suzuki examined CK19 expression in HSNCC, finding a lower rate of expression and suggesting that clinical use of OSNA only in a selected subset of HNSCC known to be CK19 positive.22 All three studies were undertaken in a Japanese population with a variety of stages and sites of HNSCC.