Abstract
INTRODUCTION: Primary thyroid leiomyosarcoma is an extremely rare soft tissue sarcoma, characterized by high malignancy and poor prognosis. Currently, only 13 cases of primary thyroid leiomyosarcoma have been described in the medical literature (limited to English). CASE PRESENTATION: A 76-year-old female presented with a giant neck mass. Physical examination revealed a large, firm mass in the left thyroid gland. No symptoms such as hoarseness or dysphagia were noted at the time of presentation. The patient underwent unilateral thyroidectomy and cervical lymph node dissection. CLINICAL DISCUSSION: Pathologic findings revealed a low-grade sarcoma with spindle-shaped tumor cells in an interwoven, sheet-like distribution. Immunohistochemistry showed positivity for desmin, SMMHC, STAT6, CK19, and Galectin3, but negativity for S-100, MyoD1, CD34, CK (AE1/AE3), CD117, and CD56. The findings were consistent with thyroid leiomyosarcoma. CONCLUSION: The treatment of primary thyroid LMS presents challenges due to its atypical symptoms and high malignance, highlighting the imperative for further exploration of therapeutic strategies to improve the outcomes.