Ectopic submandibular thyroid tissue with a coexisting normally located multinodular goitre: case report and review of the literature

The simultaneous finding of submandibular ectopic thyroid tissue and functional orthotopic thyroid gland is an extremely rare event. The present report describes the case of a woman presenting with a left submandibular mass, distant from a palpable multinodular goitre. Ultrasonography showed an ovoidal solid mass adjacent to the lower margin of the left submandibular gland. Cytological specimens showed colloid material and thyroid follicular cells with no malignant features. A preoperative CT scan demonstrated a very thin connection between the thyroid and the submandibular mass. The patient underwent total thyroidectomy and excision of the submandibular mass. The histopathological diagnosis of the thyroid tissue was multinodular goitre, and the submandibular mass was ectopic thyroid tissue showing a hyperplastic pattern. The main differential diagnosis of the submandibular mass was a metastasis from a well differentiated cancer. This case illustrates that an ectopic thyroid off the midline may not necessarily be a metastasis from a thyroid cancer.