The presentation of differentiated thyroid carcinoma occurring as a second primary associated with head and neck squamous cell carcinoma is quite unusual. Here, we present an unexpected synchronous diagnosis of two independent head and neck malignancies. A 78-year-old male with a rapidly growing, firm, and ulcerated lesion on the lower lip was referred to our clinic. Positron emission tomography-computed tomography scan performed for systemic screening demonstrated a dense hypermetabolic activity located in the right thyroid lobe, suggesting a second malignancy. Fine-needle aspiration cytology of the right thyroid gland performed to differentiate the presence of a metastatic lesion, or primary thyroid cancer was compatible with malign cytology related to papillary thyroid carcinoma. Multiple malignancies may be diagnosed synchronously in the head and neck region and these patients with multiple malignant lesions should be evaluated carefully before being accepted as metastatic.