Home > Oral cavity & oropharynx > Lingual thyroid

Oral cavity & oropharynx

Developmental anomalies

Lingual thyroid

Last author update: 1 February 2016

Last staff update: 27 October 2023

Copyright: 2002-2024, PathologyOutlines.com, Inc.

PubMed Search: Lingual thyroid

See also: Ectopic thyroid tissue

Table of Contents

Cite this page: Bychkov A. Lingual thyroid. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/oralcavitylingualthyroid.html. Accessed December 26th, 2024.

Definition / general

Developmental anomaly in which ectopic thyroid gland is located at the base of tongue
Tongue is the most common site for total thyroid ectopia
First reported by Hickman in 1869 (AMA Arch Otolaryngol 1953;57:60)

Epidemiology

Prevalence in general population is 1 per 10,000 - 100,000 people (Endocr Pract 2016;22:343)
Historically, thyroid tissue has been found in the tongue in 10% of autopsies (J Pathol 1970;102:239, Oral Surg Oral Med Oral Pathol 1972;34:781)
F:M = 3 - 7:1
Mean age at presentation is about 40 years, ranging from infancy to 83 years (Eur J Endocrinol 2011;165:375)
Some studies report a bimodal age distribution, with peaks in 2nd and 4th decades (Br J Surg 1979;66:537)

Sites

Most cases arise superficially or submucosally along the midline of base of the tongue between foramen cecum and epiglottis
Sublingual types (body of the tongue) are rarer and may be suprahyoid, infrahyoid or at the level of the hyoid bone

Pathophysiology / etiology

Failure of thyroid gland to descend from the foramen cecum to its normal prelaryngeal location
Pathogenesis is unclear, but there are speculations that maternal antithyroid immunoglobulin may stop thyroid gland descent (Barnes: Surgical Pathology of the Head and Neck, 3rd Edition, 2008)
Hypothyroidism is commonly seen in patients with lingual thyroid and some have hypothesized that lingual thyroid is a hyperplastic physiologic response by small thyroid remnants in the tongue to a low thyroid hormone level
Mutation in the genes of thyroid specific transcription factors TTF1, TTF2 (FOXE1) and PAX8 might be involved in thyroid arrest in tongue, as was shown in animals (Nat Genet 1998;19:395); however, no mutation in known genes has so far been associated with the human ectopic thyroid

Clinical features

Most lingual thyroids are asymptomatic
Symptomatic lingual ectopia is often manifested in women during puberty, pregnancy or menstruation
Most common symptoms are dysphagia, dyspnea and upper airway obstruction; other symptoms are foreign body sensation, pain, hemoptysis, dysphonia, snoring and sleep apnea (Endocr Pract 2016;22:343)
In more than 75% of patients, orthotopic thyroid is absent (total migration failure) and lingual thyroid represents the only thyroid tissue; as a result, 70% of patients with symptomatic lingual thyroid are hypothyroid; hyperthyroidism is exceptionally rare (Int J Surg 2014;12:S3)
Malignant neoplasms may arise in up to 1% of lingual thyroids; 50+ cases have been reported (J Clin Endocrinol Metab 2011;96:2684)
- Most are follicular carcinomas
- However, recent reports more often encounter papillary carcinomas, which probably reflects greater recognition of the follicular variant of papillary carcinoma (Nikiforov: Diagnostic Pathology and Molecular Genetics of the Thyroid, 2nd Edition, 2012)

Diagnosis

Radionuclide scan with technetium or radioiodine
CT, MRI and angiography are important for the preoperative assessment of patients
FNA helps to differentiate benign from neoplastic conditions
Incisional biopsy is discouraged due to risk of complications, e.g. infection, necrosis or hemorrhage (Wenig: Atlas of Head and Neck Pathology, 3rd Edition, 2015)

Laboratory

Hypothyroidism (low T3 and T4, high TSH)

Radiology description

MRI is useful in estimating extent of a lesion, because it can clearly distinguish thyroid tissue (low-intermediate T2 signal) from the tongue muscle (Hormones (Athens) 2011;10:261)

Radiology images

Images hosted on other servers:

CT and laryngoscopy

SPECT / CT

CT scan:

Distinct margins

Lingual thyroid

Well defined mass

Aberrant thyroid tissue

48-year-old white female with obstructive lingual thyroid

MRI:

Axial MRI: lingual thyroid

38 year old female

Radionuclide scan:

Scintigraphy with Tc-99m

Tc99m pertechnetate planar image

99mTcO4 radionuclide thyroid scan

Thyroid scintigraphy

Angiography:

External carotid artery angiogram

Ectopic thyroid

Carotid arteriography

Prognostic factors

Prognosis is good, since resection of lingual thyroid achieves significant improvement in patient symptoms with low rates of recurrence (Wenig: Atlas of Head and Neck Pathology, 3rd Edition, 2015)

Case reports

7 year old girl with Hashimoto thyroiditis in lingual thyroid (BMJ Case Rep 2013;2013:bcr2013200247)
12 year old girl with ectopic lingual thyroid (Case Rep Pediatr 2015;2015:252357)
12 year old boy with hyperfuctioning lingual thyroid (J Anaesthesiol Clin Pharmacol 2013;29:132)
15 year old girl with lingual thyroid and TSH secreting pituitary adenoma (Case Rep Endocrinol 2013;2013:570847)
24 year old woman with follicular adenoma of sublingual ectopic thyroid gland (J Med Case Rep 2014;8:270)
25 year old woman with fine needle aspiration diagnosis of hyperfunctioning ectopic thyroid (Acta Cytol 2005;49:228)
26 year old man with hemoptysis caused by ectopic lingual thyroid (Quant Imaging Med Surg 2015;5:480)
31 year old man with ectopic lingual goiter (Acta Otorhinolaryngol Ital 2013;33:343)
40 year old woman with lingual thyroid (Ann Maxillofac Surg 2015;5:104)
45 year old woman with dyspnea caused by lingual thyroid (N Engl J Med 2012;366:e15)
60 year old man with ectopic lingual thyroid with a multinodular goiter (Surgery 2013;153:294)
63 year old woman with differentiated thyroid carcinoma in lingual thyroid (Endocrine 2016;51:189)

Treatment

Small lesions without symptoms usually require no therapy
Nonsurgical treatment includes thyroid hormone and radioiodine ablation to induce tissue regression (Int J Surg 2014;12:S3)
Major indications for surgical excision are airway obstruction and repeated significant hemorrhage
- Transoral robotic surgery (TORS) is the most advanced surgical technique (Thyroid 2013;23:466)
- Most patients with lingual thyroid have no other thyroid tissue and acute hypothyroidism may occur after surgical removal
- Autotransplantation of pieces of lingual thyroid into the neck soft tissues may be considered

Clinical images

Images hosted on other servers:

Tongue mass:

Endoscopy:

Flexible and rigid

Swelling

Lingual thyroid in surgery:

Exposed tumor

Intraoperative photograph and surgical specimen

Gross description

Midline of base of tongue, usually between circumvallate papillae and epiglottis
Dome shaped, soft to firm mass with smooth surface, rarely ulcerated
Several mm to several cm in size (mean 2 - 3 cm)
Red, smooth to lobulated to nodular, either well or ill defined on sectioning

Gross images

Images hosted on other servers:

Excised specimen

Microscopic (histologic) description

Thyroid tissue appears normal, with normofollicular and microfollicular patterns
Follicular cells are benign in appearance, without nuclear features of papillary carcinoma
Thyroid tissue usually grows between skeletal muscle and minor salivary glands of tongue, which may simulate tumor invasion
Circumscribed and encapsulated arrangement is rare
Diagnosis of primary thyroid carcinoma in a lingual site requires vascular invasion, unequivocal infiltration with desmoplastic response or metastasis in the absence of another primary site (Endocr Pathol 2002;13:353)

Microscopic (histologic) images

Contributed by Andrey Bychkov, M.D., Ph.D. and AFIP

Enlarged thyroid follicles

Resembles malignancy

Images hosted on other servers:

With skeletal muscle

Thyroid follicles

Papillary thyroid
carcinoma in
lingual thyroid

Virtual slides

Images hosted on other servers:

Lingual thyroid with follicular carcinoma

Cytology description

Clusters of follicular cells and colloid, with usual hemorrhagic background (Acta Cytol 2005;49:228)
Features of associated pathological conditions, e.g. inflammatory and neoplastic, if such are present (Cytopathology 2013;24:275)

Cytology images

Images hosted on other servers:

Follicular cells

Positive stains

Immunophenotype of thyroid tissue: thyroglobulin, TTF1 in follicular cells and calcitonin in C cells (J Clin Endocrinol Metab 2012;97:951)

Molecular / cytogenetics description

Mutations typical for thyroid cancer (BRAF V600E, NRAS, HRAS, KRAS) are absent in benign appearing ectopic thyroid tissue (Int J Surg Pathol 2015;23:170)

Videos

Ectopic thyroid in a 6 year old child

Differential diagnosis

Lingual thyroglossal duct cyst
Lymphoepithelial cyst of oral cavity
Some tumors in oral cavity may mimic papillary thyroid carcinoma (Wenig: Atlas of Head and Neck Pathology, 3rd Edition, 2015)
- Cribriform adenocarcinoma of minor salivary glands of oral cavity: thyroglobulin-, TTF1-
- Low grade nasopharyngeal papillary adenocarcinoma: thyroglobulin-, TTF1+

Home > Oral cavity & oropharynx > Lingual thyroid