Skip to content
How It Works
Explore
Resources Ask a Question
Who It's For
Patients
Decode results, prep for appointments, weigh options.
Caregivers & advocates
Carry the research load for someone you love.
Providers & clinicians
Resources for patients in your practice.
Log In Ask a Question
PubMed This is a summary of 17 peer-reviewed journal articles Updated
Endocrinology

The Biology and Diagnosis of Thyroid Ectopia

At a Glance

Thyroid ectopia occurs when the thyroid gland develops in the wrong location, such as the base of the tongue. It must be accurately diagnosed using ultrasound or scintigraphy before removing any neck lump, as this ectopic mass may be the patient's only functioning thyroid tissue.

To understand thyroid ectopia, it helps to think of the thyroid gland as a traveler. During a baby’s development in the womb, the thyroid doesn’t start in the neck; it begins at the base of the tongue [1]. Understanding this journey—and what happens when it goes off track—is key to diagnosing the condition correctly.

The Thyroid’s Journey (Embryology)

In a typical pregnancy, the thyroid gland begins to form around the third or fourth week of development [2]. It starts at a spot called the foramen cecum, located at the back of the tongue [1]. From there, it must travel down through the tissues of the neck to its final “home” just below the Adam’s apple [1].

As it moves, it stays connected to the tongue by a thin tube called the thyroglossal duct, which usually disappears once the thyroid reaches its destination [3]. Thyroid ectopia occurs when this journey is interrupted. The gland may stop too early, most commonly resulting in a lingual thyroid (a thyroid gland located entirely at the base of the tongue) [1][4]. It can also get “stuck” anywhere along that path or, in rare cases, travel too far down into the chest (mediastinal thyroid) [1].

The Genetic “Map”

The thyroid’s movement is guided by a specific set of genetic instructions. If there is a “typo” in these instructions, the gland may not form or move correctly. Scientists have identified several key genes involved in this process:

  • PAX8 and FOXE1: These genes act like a GPS for the developing thyroid, helping it migrate and develop into the right shape [2][5]. Mutations in FOXE1 can sometimes be linked to other features like a cleft palate [6].
  • NKX2-1: This gene helps manage the development of the thyroid, lungs, and parts of the brain. A mutation here might cause “brain-lung-thyroid syndrome,” a triad of symptoms involving respiratory issues and movement disorders (like benign chorea) alongside the thyroid issues [7].
  • NKX2-5: While less common, mutations in this gene are sometimes linked to heart defects alongside thyroid issues [8][9].

Telling the Difference: Differential Diagnosis

Because thyroid ectopia often looks like a simple lump in the middle of the neck, it is frequently confused with other conditions. This is known as a differential diagnosis—the process doctors use to distinguish between similar-looking problems.

Condition Description How Doctors Distinguish It
Thyroglossal Duct Cyst (TGDC) A fluid-filled sac left over from the path the thyroid took [10]. Often moves upward when the person sticks out their tongue [1].
Dermoid Cyst A slow-growing growth containing skin, hair, or fat [11]. Usually looks different on an MRI; it may appear “fatty” or “greasy” inside [11].
Swollen Lymph Node A small bean-shaped gland that swells during infection. Usually located more to the side of the neck rather than the exact midline.

Why the Distinction Matters

It is vital for doctors to confirm if a neck mass is ectopic thyroid tissue before any surgery is performed [12]. In many cases of thyroid ectopia, the “lump” is the only thyroid tissue the patient has [13][14]. If a surgeon removes it thinking it is a simple cyst (like a thyroglossal duct cyst), the patient will become permanently hypothyroid and require lifelong hormone replacement [15][13].

To prevent this, doctors use ultrasound to see if a normal thyroid gland exists in the neck and scintigraphy (a “thyroid scan”) to see if the lump is actually functioning thyroid tissue [16][17].

Common questions in this guide

What is thyroid ectopia?
Thyroid ectopia is a developmental condition where the thyroid gland forms in the wrong place during pregnancy. Instead of sitting in the lower front of the neck, it gets stuck along its developmental path, often remaining at the base of the tongue.
Why is an ultrasound or thyroid scan necessary for a neck lump?
Imaging tests like ultrasounds and thyroid scans are crucial to confirm if a neck lump is functioning thyroid tissue. This is critical because an ectopic thyroid is often the only thyroid tissue a patient has, and accidentally removing it causes permanent hypothyroidism.
How is an ectopic thyroid different from a thyroglossal duct cyst?
While both can cause a lump in the middle of the neck, a thyroglossal duct cyst is a fluid-filled sac left over from fetal development. In contrast, an ectopic thyroid is solid, functioning gland tissue that produces essential hormones.
Are there genetic causes for thyroid ectopia?
Yes, errors in certain genes like PAX8, FOXE1, and NKX2-1 can disrupt the normal development and movement of the thyroid gland. These genetic mutations act like a faulty GPS, causing the gland to stop in the wrong location.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Has a thyroid ultrasound confirmed whether my child has a normally located thyroid gland in addition to this mass?
  2. 2.If this mass is ectopic thyroid tissue, is it the only functioning thyroid tissue in the body?
  3. 3.Can we perform a thyroid scintigraphy (thyroid scan) to confirm if this lump is actually thyroid tissue?
  4. 4.Based on the mass's appearance on imaging, how can we be sure it isn't a thyroglossal duct cyst or a dermoid cyst?
  5. 5.Should we consider genetic testing for mutations like PAX8 or FOXE1, especially if there are other symptoms?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (17)
  1. 1

    Ectopic thyroid tissue presenting as a new neck mass in a pediatric patient.

    Carlson S, Campbell L, Janitz E

    Radiology case reports 2019; (14(1)):55-57 doi:10.1016/j.radcr.2018.09.018.

    PMID: 30364699
  2. 2

    GLIS3 and Thyroid: A Pleiotropic Candidate Gene for Congenital Hypothyroidism.

    Rurale G, Persani L, Marelli F

    Frontiers in endocrinology 2018; (9()):730 doi:10.3389/fendo.2018.00730.

    PMID: 30555422
  3. 3

    Papillary Thyroid Carcinoma Arising from Thyroglossal Cyst-an Institutional Experience over a Decade.

    Suresh S, Vm P, Thomas S, et al.

    Indian journal of surgical oncology 2023; (14(1)):155-159 doi:10.1007/s13193-022-01628-1.

    PMID: 36891423
  4. 4

    Ectopic colloid goiter in mediastinum with normal thyroid gland.

    Kolwalkar J, Samant D, Borkar S, et al.

    Journal of cardiothoracic surgery 2024; (19(1)):103 doi:10.1186/s13019-024-02574-5.

    PMID: 38378661
  5. 5

    A Novel Pathogenic Variant in PAX8 Leads to Familial Congenital Hypothyroidism.

    França MM, Reeve L, Dumitrescu AM, et al.

    Thyroid : official journal of the American Thyroid Association 2022; (32(8)):1000-1002 doi:10.1089/thy.2022.0117.

    PMID: 35611983
  6. 6

    A new FOXE1 homozygous frameshift variant expands the genotypic and phenotypic spectrum of Bamforth-Lazarus syndrome.

    Sarma AS, Banda L, Rao Vupputuri M, et al.

    European journal of medical genetics 2022; (65(10)):104591 doi:10.1016/j.ejmg.2022.104591.

    PMID: 35963604
  7. 7

    Disorders of thyroid morphogenesis.

    Abu-Khudir R, Larrivée-Vanier S, Wasserman JD, Deladoëy J

    Best practice & research. Clinical endocrinology & metabolism 2017; (31(2)):143-159 doi:10.1016/j.beem.2017.04.008.

    PMID: 28648504
  8. 8

    NKX2-5 Variant in Two Siblings with Thyroid Hemiagenesis.

    Szczepanek-Parulska E, Budny B, Borowczyk M, et al.

    International journal of molecular sciences 2022; (23(6)) doi:10.3390/ijms23063414.

    PMID: 35328834
  9. 9

    The c.63A>G polymorphism in the NKX2.5 gene is associated with thyroid hypoplasia in children with thyroid dysgenesis.

    Cerqueira TL, Ramos Y, Strappa G, et al.

    Archives of endocrinology and metabolism 2015; (59(6)):562-7.

    PMID: 26421664
  10. 10

    Papillary carcinoma in correlation to thyroidal duct cyst: A case series.

    Bahar A, Torabizadeh Z, Movahedi Rad M, Kashi Z

    Caspian journal of internal medicine 2020; (11(1)):110-115 doi:10.22088/cjim.11.1.110.

    PMID: 32042395
  11. 11

    Ectopic thyroid tissue in the anterior mediastinum along with a normally located gland.

    Kola E, Gjata A, Kola I, et al.

    Radiology case reports 2021; (16(11)):3191-3195 doi:10.1016/j.radcr.2021.07.064.

    PMID: 34484517
  12. 12

    Dual thyroid ectopia-role of thyroid scintigraphy and neck ultrasonography.

    Jain TK, Meena RS, Bhatia A, et al.

    Indian journal of nuclear medicine : IJNM : the official journal of the Society of Nuclear Medicine, India 2015; (30(4)):338-40 doi:10.4103/0972-3919.164023.

    PMID: 26430320
  13. 13

    [Ectopic thyroid gland: clinical features and diagnostics in children].

    Shreder EV, Vadina TA, Konyukhova MB, et al.

    Problemy endokrinologii 2022; (68(3)):76-85 doi:10.14341/probl12876.

    PMID: 35841171
  14. 14

    Management of suspected thyroglossal duct cysts.

    Povey HG, Selvachandran H, Peters RT, Jones MO

    Journal of pediatric surgery 2018; (53(2)):281-282 doi:10.1016/j.jpedsurg.2017.11.019.

    PMID: 29305009
  15. 15

    Intratracheal Ectopic Thyroid Tissue Mimicking a Subglottic Mass in a Patient With Thyroid Follicular Carcinoma on SPECT/CT.

    Aydinbelge Dizdar N, Cinar A, Ozmen O, Senlik SD

    Clinical nuclear medicine 2025; (50(2)):e87-e89 doi:10.1097/RLU.0000000000005468.

    PMID: 39354693
  16. 16

    Usefulness of Hybrid Single-Photon Emission Computed Tomography/ Computed Tomography in a Case of Ectopic Thyroid Tissue in the Thyroglossal Duct Remnant.

    Calandri E, Filippi L, Alessandro F, et al.

    Indian journal of nuclear medicine : IJNM : the official journal of the Society of Nuclear Medicine, India 2021; (36(1)):97-99 doi:10.4103/ijnm.IJNM_43_20.

    PMID: 34040314
  17. 17

    Incidental Finding of Triple Ectopic Thyroid: Case Report and Review of the Literature.

    Zeineddine F, El-Hajj G, Hajj MA, Chahinian R

    Asia Oceania journal of nuclear medicine & biology 2024; (12(2)):179-184 doi:10.22038/AOJNMB.2024.75895.1532.

    PMID: 39050238

This page explains the biology and diagnosis of thyroid ectopia for educational purposes and does not replace professional medical advice. Always consult your endocrinologist or pediatrician regarding neck masses and imaging tests.

Get notified when new evidence is published on Thyroid ectopia.

We monitor PubMed for new peer-reviewed studies on this topic and email a short summary when something meaningful changes.