Teratocarcinosarcoma is a rare and aggressive tumor usually affecting the sinonasal tract. It arises primarily from the nasal cavity, paranasal sinuses with some reported cases arising from the nasopharynx and oral cavity and commonly referred to as Sinonasal Teratocarcinosarcoma (SNTC). We present the first case of teratocarcinosarcoma as a primary thyroid cancer in a 17-year-old male patient who presented with a rapidly growing anterior neck mass with no symptoms. Physical examination revealed circa 4 cm × 5 cm slightly right sided, non-tender, firm anterior neck swelling. A thyroid ultrasound revealed an enlarged thyroid gland with multiple thyroid nodes. Magnetic Resonance Imaging (MRI) of the head and neck showed no sinonasal tract tumor. Thyroidectomy and surgical resection of the tumor was performed. Histological examination revealed teratocarcinosarcoma of the thyroid gland, an analog to SNTC with no primary sinonasal tissue involvement. This implies that, teratocarcinosarcoma can occur in primary tissues other than sinonasal origin contrary to conventional knowledge.