case of the week : thyroglossal cyst

Case presentation :

Thyroglossal cyst

Dr.Abdalla Mutwakil Gamal

Radiology Deparment

Sebha Medical Center

Content

• The case

• Thyroglossal cysts

• Imaging Thyroglossal cysts

• Differential diagnosis

THE CASE

History

• 17 years old male, presented with a painful neck swelling. The swelling was

painless and small in size when it was first noticed when the patient was 7

years old. In the last two months the swelling increased in size and started

to become painful and to cause slight discomfort on swallowing.

• OSR : Increased fatiguability. No heat or cold intolerance. No change in

bowel or sleep habits. No increased irritability. No palpitation.

• PH : anaemia that needed transfusion of 2 units of blood when the patient

was 7 years old.

• FH : Mother has hyperthyroidism for the last 16 years and is on

carbimazole.

General Examination

• GE :

– NAD

– PR = 92 bpm

Local Examination

Single swelling in front of the neck at the midline, oval in shape, about 3x4 cm

in shape, overlying skin is red and shiny but shows no scars, sinuses or

ulcers. The swelling moves with deglutition but not with tongue protrusion !

On palpation, the swelling is warm and tender. Soft in consistency with +ve

fluctuation. No palpable cervical lymph node enlargement.

Investigations

• CBC = Not available

• TFT

– T3 = 1.0 ng/ml (Normal = 0.6 – 1.85)

– T4 = 8.7 µg/dL (Normal = 4.8 – 12)

– TSH = 0.8 (Normal = 0.3–3.0 µIU/mL)

• Others

– RBS = 77 mg/dL

– Urea = 15 mg/dL

Ultrasound

Evidance of complicated cyst in the subcutenous tissue in the midline

of the neck with thick fluid inside measuring about 3x4 cm

CT Scan

Differential diagnosis

• Midline neck lump :

– Submental lymph nodes

– Thyroglossal cyst

– Thyroid swelling

– Dermoid cyst

THYROGLOSSAL CYSTS

Definition

• A thyroglossal cyst is

a fibrous cyst that

forms from a

persistent

thyroglossal duct.

Embryology

• 4th week of gestation :

proliferation

• 7th week, complete

descend

• Duct disappearance

Epidemiology

• They typically present during childhood

(90% before the age of 10), or remain

asymptomatic until they become infected,

in which case they can present at any

time.

• Thyroglossal duct cysts account for 70%

of all congenital neck anomalies, and are

the second most common benign neck

mass, after lymphadenopathy.

Presentation

• The following are the most common symptoms of a

thyroglossal duct cyst. However, each child may

experience symptoms differently. Symptoms may

include:

• A small, soft, round mass in the center front of the neck

• Tenderness, redness, and swelling of the mass, if

infected

• A small opening in the skin near the mass, with drainage

of mucus from the cyst

• Difficulty swallowing or breathing

Complications

• Cyst infection (follows Upper Respiratory Infection)

• Papillary carcinoma (in adults)

Treatment

• Infected thyroglossal cyst

– Majority respond to antibiotics.

– Surgical drainage if abscess formed or failure

to respond to antibiotics.

– Elective excision of the cyst once acute

infection has resolved.

• Surgery

– Excision is recommended for most cysts.

IMAGING THYROGLOSSAL CYSTS

Imaging options

• Ultrasonography

• Computed Tomography

• Magnetic Resonance Imaging

Ultrasonography

• Unless infected, they are painless, fluctuant masses

which spread the strap muscles. The fluid is usually

anechoic and the walls are thin, without internal

vascularity.

• However, in some cases, the internal fluid may contain

debris. This is particularly the case in the adult patient

where the cysts may be complex heterogeneous

masses.

• If there is associated infection, there may be surrounding

inflammatory change.

• Ultrasound image demonstrates a

midline infrahyoid unilocular mass

with a homogeneously hypoechoic

internal echotexture, typical of a

TDC.

• O/E - Left paramedian swelling.

• Cystic swelling at level of hyoid

bone. Flow is seen in septa.

• Well-defined lesion is noted at

level of hyoid and infrainfrahyoid

level. It is in mid line and

predominently in right paramedian

location.

• It is mainly cystic lesion with few

septa / echoes. NO calcification is

noted.

• It is deep to platysma.

• It is superficial to strap muscles.

• Vascularity is noted in wall and in

solid parts.

• A well-defined cystic lesion with

internal echoes and debris is

noted in mid line. Lower border of

the lesion abutts hyoid bone.

Lesion shows wall thickening and

vascularity.

• No perilesional hypervascularity is

noted.

• Location and ultrasound features

favour thyroglossal duct cyst.

Infected thyroglossal duct cyst

longitudinal

Thyroglossal duct cyst with a

vascularized wall

Infected thick walled thyroglossal

duct cyst

Thyroglossal duct cyst with a

vascularized wall

Computed Tomography

• At CT, thyroglossal duct cysts are thin walled, smooth, well defined

homogeneously attenuating lesions with an anterior midline or para-midline

location. The generally accepted rule is that they should be within 2 cms of

the midline. The may demonstrate slight rim (capsular) enhancement.

• Sternocleidomastoid is typically displaced posteriorly or posterolaterally and

in some cases, they may be embedded in the infrahyoid strap muscles.

• Computed tomography has a high degree of diagnostic accuracy for

thyroglossal duct cysts (TDC). The most helpful features in the differential

diagnosis are the midline location, most often at or below the hyoid bone,

and the intimate relationship of infrahyoid TDCs to the strap muscles. CT

better evaluates the potential for thyroglossal duct carcinoma and is thus

preferred in adult patients.

• Axial contrast-enhanced CT

shows a large cystic lesion at the

level of the thyroid cartilage,

slightly to the right of midline,

embedded in the right strap

muscles, consistent with a TDC.

• Sagittal CT image in a 76-year-old

man with a rapidly enlarging neck

mass shows a large infrahyoid

cystic lesion representing

pathologically proven thyroglossal

duct cyst carcinoma

• Thyroglossal duct cyst .

Reconstructed CT scan of the

neck demonstrates a midline

cystic lesion with a slightly

enhancing wall. The contents

measured fluid density.

• Thyroglossal duct cyst in a 41-

year-old man Axial contrast-

enhanced CT scans show a cystic

mass in the anterior midline of the

• 25 years old male cyst.

• Axial :: CT w/contrast (IV)

Thyroglossal Duct Cyst Midline

cystic structure

Magnetic Resonance Imaging

• T1: variable

– low signal: if low protein / uncomplicated

– high signal (most common 6) due to

• previous haemorrhage / infection

• high protein (probably due to previous complication)

• T2 - typically high signal

• T1 C+ (Gd)

– no enhancement in uncomplicated cysts

– thin peripheral enhancement may be seen

• Axial T1-weighted image obtained

following intravenous gadolinium

administration demonstrates

peripheral rim enhancement of the

thyroglossal duct cyst.

• A sagittal T1-weighted

postcontrast image in the same

patient as in the previous image

nicely depicts the midline

thyroglossal duct cyst and its

location relative to the airway,

tongue base, hyoid bone, and

strap muscles.

DIFFERENTIAL DIAGNOSIS

Differential diagnosis

• Midline neck lump :

– Submental lymph nodes

– Thyroglossal cyst

– Thyroid swelling

– Dermoid cyst

Submental lymph nodes

• Drainage Pattern

– Lower lip

– Floor of Mouth

– Tip of Tongue

– Skin of Cheek

Thyroid swelling

• A 12-year-old patient with an

asymptomatic, palpable thyroid

nodule, which was noticed

upon routine physical

examination.

• Roughly 5% of thyroid nodules

are malignant; the remainder

represent a variety of benign

diagnoses, including colloid

nodules, degenerative cysts,

hyperplasia, thyroiditis, or

benign neoplasms.

Dermoid cysts

• A dermoid cyst is a pocket or

cavity under the skin that

contains tissues normally

present in the outer layers of

the skin. The pocket forms a

mass that is sometimes visible

at birth or in early infancy but

often is not seen until later

years. Dermoid cysts are

usually found on the head or

neck and face, but can occur

anywhere on the body.