Ectopic lingual thyroid tissue is an uncommon developmental anomaly. Tumours of identical pathological characteristics as those arising in the eutropic thyroid tissue, may be present in ectopic locations. There are very few cases of malignant tumours reported in the literature. Here we report a review of this pathology and we describe a case of a papillary carcinoma of the base of the tongue, located in ectopic lingual thyroid tissue, in a 66 year-old white man, complaining of dysphagia and oral bleeding. Surgical treatment was carried out, consisting of radical resection of the right hemineck, tumour resection, right hemiglossectomy and total thyroidectomy. Postoperative treatment with 131I and substitutive thyroid hormonal therapy was prescribed.