Synchronous occurrence of oral squamous cell carcinoma and aggressive papillary thyroid microcarcinoma with synchronous regional metastasis in the cervical lymph nodes: a case report.

This report describes an extremely rare case of synchronous oral squamous cell carcinoma (OSCC) and aggressive papillary thyroid microcarcinoma (PTMC) presenting with synchronous regional metastasis to the cervical lymph nodes. A 56-year-old male underwent excision of a floor-of-mouth squamous cell carcinoma and supra-omohyoid neck dissection. Histopathology unexpectedly revealed distinct metastatic components of both OSCC and PTMC within the same lymphatic basin, despite unremarkable preoperative thyroid imaging. Total thyroidectomy subsequently confirmed bilateral microscopic PTMC (0.1 mm) with skip metastases to the lateral neck. To avoid radiation-induced fibrosis that would complicate thyroid surgery, thyroidectomy was prioritized over adjuvant radiotherapy for the oral malignancy. This case challenges the perception of PTMC as an indolent disease and highlights the need for multidisciplinary surgical sequencing and high diagnostic vigilance when managing dual head and neck malignancies.