Primary Leiomyosarcoma of the Thyroid Gland - A Rare Malignancy.

: Primary leiomyosarcoma (LMS) of thyroid is rare malignant neoplasm usually seen in elderly patients. These tumours are characterised by a rapidly growing mass in the neck, difficult to diagnose preoperatively and are highly aggressive with high recurrence rates in spite of radical surgery, chemotherapy and radiotherapy. We herein report a case of 50-year-old female with a rapidly growing painless mass in the neck. Total thyroidectomy with bilateral neck node clearance was done. Histology and Immunohistochemistry revealed primary LMS of thyroid gland. Within 1 month of radical surgery she developed local recurrence. Diagnosis of primary LMS is difficult and immunohistochemistry is necessary to differentiate it from other malignancies of the thyroid. Primary LMS remains a life-threatening tumour and more effective treatment are needed to improve outcome.