Synchronous tongue squamous cell carcinoma and papillary thyroid carcinoma with Collision metastasis to a single cervical lymph node

Abstract

Introduction: The frequency of synchronous malignant tumors in patients with squamous cell carcinoma (SCC) of the oral tongue is relatively low (2%), with the oral cavity being the most frequent secondary site, followed by the pharynx.[1] Collision tumors are defined as 2 histologically distinct neoplasms that originate from topographically separate primaries, and abut and intermix with 1 another. The main site for intermixing of 2 tumors is the lymph node. There are no areas of transition between the 2 tumors. However, collision tumors can be summarized as tumor-to-tumor metastasis with exceedingly rare incidence.[1] Proper treatment of the thyroid gland is debatable when metastatic papillary thyroid carcinoma is incidentally encountered during neck dissection for the index treatment of primary SCC of the oral tongue, considering the good prognosis for thyroid cancer and the difficulty to find the primary tumor.[2] Case report: We report a 28 years old woman with synchronous tongue squamous cell carcinoma and papillary thyroid carcinoma, with a lymph node containing metastasis from both tumors (collision node). Conclusion: Although the extreme rarity of this synchronous tumor may make it impossible to draw a significant conclusion regarding proper treatment of thyroid disease, it is important to be aware that even when primary head and neck SCC is at an advanced stage, a cure is possible. Active management of the thyroid carcinoma should be considered because it may affect prognosis, as in the present case.