Abstract
BACKGROUND: The presence of ectopic thyroid tissue is a developmental disorder that affects about one per 100,000-300,000 people. It is extraordinarily rare for ectopic thyroid to be out of the lines of its descent. This case is the first to report a cancerous ectopic thyroid in the mandibular bone with a goitrous orthotopic thyroid gland. CASE PRESENTATION: 80-year-old female of free medical background presented to our clinic with painless left mandibular swelling that recent increase in size after tooth extraction. Surprisingly the diagnosis of ectopic thyroid tissue with cancerous follicular cells was reached upon histological analysis. The goitrous thyroid gland was found in its expected cervical location, and the patient was euthyroid. CONCLUSION: Because this diagnosis extremely rare, the possibility of ectopic thyroid carcinoma in cases of a pathological mass in the mandible must always be carefully thought out. A high degree of suspicion is essential as the unusual presentation could take.