Discrepancies with Final Diagnosis in Head and Neck Intraoperative Frozen Section

PURPOSE: Creating a frozen section slide and crafting an interpretation is a multistep process with multiple possible points of failure. Head and neck frozen section pathology presents particular technical and diagnostic challenges. The aim of our study was to identify discrepancies between head/neck intraoperative and final diagnoses, determine the site of process failure, and assess the potential causes. METHODS: Concordance data from head and neck intraoperative and final diagnoses (2020-2023) were queried from our LIS-embedded quality assurance system. Discrepancies were categorized as major and minor, with major defined as those that would have altered the surgical procedure. RESULTS: We found 71 total discrepancies out of 1844 head and neck cases (3.9%). Major discrepancies accounted for 48/1844 (2.7%). Only major errors were considered for further study and were classified primarily into three categories: (1) inadequate gross sampling by the prosector, usually involving mucosal tissues of excised large specimens for evaluation of margins for dysplasia/carcinoma (14/48 cases; 29%), (2) insufficient sectioning into the block leaving undetected tissue unexamined (9/48 cases; 19%), and (3) interpretative errors (23/48 cases; 48%). The most common major interpretative errors involved the diagnosis of squamous dysplasia (9 cases), failure to identify minimally invasive squamous carcinoma (4 cases), failure to identify parathyroid and thyroid tissues (5 cases), and incorrect diagnoses of non-squamous neoplasms (5 cases). Two errors (4%) were ascribed to processing artifact issues in the frozen section. CONCLUSION: Half of diagnostic discrepancies occurred at steps prior to microscopic interpretation. Management of specimen grossing and tissue selection in large specimens, adequate block sectioning, and adherence to diagnostic criteria for difficult but common issues such as squamous dysplasia, minimally invasive carcinoma and thyroid/parathyroid morphology may help reduce intraoperative/final diagnosis discrepancies.