Role of Imaging in Clinically Occult Isolated Intrathyroidal Metastasis from Squamous Cell Carcinoma of Tongue: An Unusual Case Series.

Metastasis to the thyroid gland is rare; furthermore, intrathyroid metastasis from head and neck squamous cell carcinoma (SCC) is very unusual, with only nine previously documented cases four from intrathyroid metastasis from nasopharyngeal carcinoma, two from oral cavity, one each from oropharynx, larynx, and parotid. The reported case series are unique in nature and illustrates the role of fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) and ultrasound-guided biopsy in diagnosing clinically occult isolated intrathyroidal metastasis, which helps in the best management for an isolated intrathyroid metastases. This study details the cases of three patients who were diagnosed with intrathyroidal metastasis from SCC of the tongue by PET-CT, followed by USG-guided biopsy, who were treated with either surgery and or chemotherapy. Although intrathyroidal metastasis is an uncommon occurrence and signifies poor prognosis, early detection of an isolated intrathyroidal metastasis on imaging in an appropriately selected patients, radical surgery, and/or chemotherapy improve local control and quality of patient's life.