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Abstract The thyroid gland's neurovascular relationship is commonly portrayed as the recurrent laryngeal nerve (RLN) coursing posteriorly to the thyroid gland. We report a rare case with the RLN running anteriorly to a thyroid tumor. A 56-year-old Japanese woman underwent a thyroidectomy for a benign thyroid tumor. Preoperatively, computed tomography confirmed that part of the tumor had extended into the mediastinum and was descending posteriorly up to the brachiocephalic artery. Intraoperatively, when the sternothyroid muscle was incised to expose the thyroid gland, a cord (nerve)-like structure was observed directly anterior to the thyroid tumor. Although the course of this cord-like structure was clearly different from the "traditional" course of the right RLN, the possibility that the structure was the RLN could not be excluded. The structure was traced back in order to preserve it; we saw that it entered the larynx at the lower margin of the cricothyroid muscle and approximately at the level of the cricothyroid junction through the back of the normal thyroid tissue. With intraoperative neuromonitoring, the structure was identified as the RLN. As a result, the course of the RLN run anterior to the tumor but then posterior to the 'normal thyroid' i.e. into it normal anatomical position. Had we assumed that the RLN was behind the thyroid tumor, we would have damaged the RLN. It would not be possible to diagnose this abnormal running course of the RLN reliably before surgery, but extra care should be taken in similar cases, that is, when a large thyroid tumor is descending posteriorly up to the brachiocephalic artery on the right side.

Human papillomavirus (HPV)-related oropharyngeal small-cell carcinoma (OPSmCC) is a rare malignancy with aggressive behavior, whereas HPV-related oropharyngeal squamous-cell carcinoma (OPSqCC) displays a favorable prognosis. Notably, these two malignancies occasionally arise in an identical tumor. In this case study, we explored the molecular characteristics that distinguishes these two carcinomas using a rare case of HPV-related oropharyngeal carcinoma (OPC) with the combined histology of SmCC and SqCC. Immunohistochemical analysis and HPV-RNA in situ hybridization (ISH) suggested that both SmCC and SqCC were HPV-related malignancies. Targeted exome sequencing revealed that SmCC and SqCC had no significant difference in mutations of known driver genes. In contrast, RNA sequencing followed by bioinformatic analyses suggested that aberrant transcriptional programs may be responsible for the neuroendocrine differentiation of HPV-related OPC. Compared to SqCC, genes up-regulated in SmCC were functionally enriched in inflammatory and immune responses (e.g., arachidonic acid metabolism). We then developed a SmCC-like gene module (top 10 up-regulated genes) and found that OPC patients with high module activity showed poor prognosis in The Cancer Genome Atlas (TCGA) and GSE65858 cohort. Gene set enrichment analysis of the SmCC-like gene module suggested its link to MYC proto-oncogene in the TCGA data set. Taken together, these findings suggest that the SmCC-like gene module may contribute to acquisition of aggressive phenotypes and tumor heterogeneity of HPV-related OPC. The present case study is the first report of genetic and transcriptomic aberrations in HPV-related OPSmCC combined with SqCC. [ABSTRACT FROM AUTHOR]