Primary Mucoepidermoid Carcinoma of the Thyroid: A Report of a Rare Case with Bone Metastasis and Review of the Literature.

Mucoepidermoid carcinomas (MECs) are generally found in salivary gland, but they have also been mentioned in other organs such as the larynx, esophagus, breast. MECs are considered to be a low-grade carcinoma and their occurrence in the thyroid is extremely rare. We present a 54-year-old male patient admitted to our clinic, complaining about having back pains for approximately three months. A lumbosacral spine MRI and a PET/CT scan revealed multiple lesions in the L4, L5, S1 vertebra bodies, sacral bone and left pelvis bone, suggesting of a metastatic disease. The result of thyroid FNA was carcinoma and a biopsy of the vertebra bone confirmed the presence of a metastatic carcinoma. A total thyroidectomy and level VI neck dissection was conducted followed by palliative external beam radiotherapy (30 Gy) to the vertebra bodies, sacral bone and left pelvis bone. In pathological studies, the diagnosis of thyroid mucoepidermoid carcinoma was confirmed. Six months after treatment, the patient died due to severe pain and fatigue caused by the disease. Here, we report a rare case with bone metastasis as the first symptom of MEC and a brief review of published literature on the subject.