A 44-year-old Iranian woman with Cacausian ethnicity presented with an anterior midline neck mass that gradually appeared without tenderness over three months. The patient had a history of frequent painful swelling of the anterior part of her neck, which subsided with antibiotics therapy. A physical examination of the patient revealed a 100 × 55 mm mass that was painless, smooth and hard. The mass was located on the anterior part of the patient's neck and extended from the suprahyoid portion to the thyroid gland. The thyroid gland could not be separated from the mass. Thyroid functional tests (serum thyroxine, triiodothyronine and thyroid stimulating hormone) were within normal limits. A thyroid scan with technetium pertechnetate detected a cold nodule corresponding to the mass in the left lobe of the thyroid gland. A computed tomography scan (CT) revealed a relatively large (100 × 55 × 48 mm), heterogeneous enhancing soft tissue mass with a cystic component in the midline of the anterior neck space, that extended from the base of the tongue to the inferior aspect of the thyroid gland and the bilateral aspect of the submandibular gland. The mass was completely separated from the tongue muscles. The destruction of the hyoid bone and chondrolysis of the thyroid cartilage were also seen. A hypodense lesion in the left thyroid lobe and some adenopathy in the submandibular space were detected. A fine needle aspiration (FNA) revealed a papillary carcinoma. The tumor mass, together with the thyroid gland, the hyoid bone and the bilateral cervical lymph node were therefore removed. Although the thyroid gland was not involved, some micrometastases in the cervical lymph nodes were seen. The pathological report revealed a papillary carcinoma arising with a 100 × 53 mm TDC. The pathologic report described in detail the occurrence of complex, branching and randomly oriented papillae with a central fibrovascular core and a single or stratified lining of cuboidal cells with a zoom in of 10 (×10). In addition, nuclear features showed optically clear (ground glass) nuclei and nuclear grooves (×40), indicating a malignant papillary carcinoma. Postoperative radioactive iodine treatment and thyroid hormone supplements were recommended. The patient was followed up with a clinical examination, thyroid scintigraphy and ultrasonography of the operation site. The tumor had not recurred one year after the operation.