1. The document discusses various cystic lesions that can occur in the suprahyoid neck region on CT and MRI imaging. These include thyroglossal duct cysts, laryngocoeles, branchial cleft cysts, lymphangiomas, dermoid/epidermoid cysts, ranulas, and others. 2. Each cystic lesion is described in terms of its typical location, imaging appearance on CT and MRI, differential diagnosis and distinguishing features. For example, thyroglossal duct cysts appear as midline cysts related to the hyoid bone, while branchial cleft cysts occur in characteristic locations based on the branchial arch involved. 3. Understanding the anatomy

1. SUPRAHYOID CYSTIC LESIONS ON
CT & MRI
Adnan Rashid, MD
The British Institute of Radiology,UK.
Presented:
Dept of Radiology, UTMB,Galveston,Tx, USA
Dept of Radiology , SIMS, Services Hospital, Lahore

2. Clinically
Neck swelling
Ultrasound scan
Cystic lesion
Further imaging
CT and MRI

3. Cystic lesion facts:
 Closed cavity or sac lined by epithelium.
 Attenuation determined by the contents of sac.
 A simple fluid-filled cyst
CT: Low density with a thin wall
MRI signal : low onT1 and high onT2WI.
 Complicated (proteinaceous fluid or haemorrhage)
 CT: soft tissue density on CT
 MRI signal : high onT1WI.
MRI features which would confirm a cystic origin are
fluid–fluid levels and propagation of artefact in the phase
encoding direction.

4. Usually Cysts have typical locations,
Good to know these Locations & Supra-
hyoid anatomy for Diagnosis!

5. Suprahyoid Spaces
Limited to Suprahyoid space;
 Masticator,
 Prestyloid parapharyngeal (PPS),
 Parotid space,
Extending down to Infrahyoid
 Post-styloid parapharyngeal /Carotid,
 Retropharyngeal
 Perivertebral

6. Displacement of the PPS
 Central to the suprahyoid spaces is the
PPS (Most mobile, mainly fat)
• Posteromedially ....masticator
• Posterolaterally……..AMS mass.
• Anteriorly or anteromedially…..
Carotid
• Anterolaterally……. Retropharyngeal
• Medial +/-anterior………. deep parotid
 Distinguishing a pre-styloid process mass
from a post-styloid carotid space mass
requires visualization of the styloid process
by computed tomography (CT) and the styloid
musculature by magnetic resonance imaging
IMRI

7. Longus colli(Perivertebral)
musculature complex
When these muscles are displaced;
 Posteriorly,
Mass of AMS(Aerodigestive Mucosal space)
Mass of retropharyngeal space.
 Anteriorly
Perivertebral (intrinsic longus colli mass is within the peri-
vertebral space).

8. Thyroglossal duct cyst
 The most common congenital neck cyst
 midline or paramedian and is closely related to the hyoid bone. It
may be suprahyoid, infrahyoid or at the level of the hyoid bone.
 A low-density cystic midline mass embedded within the strap
muscles with a smooth, thin, well-defined wall is characteristic
ComplicatedTGC;
 Increased attenuation and wall enhancement is seen if complicated by
infection.
 The presence of mural nodules or foci of calcification within the cyst would
suggest thyroglossal duct CA

10. Laryngocoele
 Dilated laryngeal saccule(air or fluid filled)
arising from the laryngeal ventricle.
 Change size with theValsalva manoeuvre.
 Primary (e.g. in glass blowers and wind instrument players),
 Secondary due to an obstructing lesion (squamous cell
carcinoma)
OnT2WI:The tumour is low signal intensity to fluid within the
laryngocoele.

11.  Internal laryngocoeles; paraglottic space lateral to the
false cord in the supraglottis.
 External laryngocoele occurs when the lesion herniates
through the thyrohyoid membrane.
 Mixed lesions; contain internal and external
components.

12. Internal laryngocoele (arrow) with extension
from the laryngeal ventricle.
secondary left internal fluid filled laryngocoele
(arrow) from a laryngeal carcinoma (arrowhead)

13. Branchial cleft cysts
 Incomplete obliteration of a portion of the branchial apparatus.
 CT and MRI show a cystic lesion in the typical location
 A first branchial cleft :
Can be from the external auditory canal (EAC) through the parotid
gland to the submandibular region.
 .

14. second branchial
 May cause fistulas, sinuses or cysts(#1).
 It can occur anywhere from the tonsillar fossa to the supraclavicular
region.
 Bailey classification:
Type I cyst: most superficial and lies along the anterior surface of
the sternocleidomastoid muscle, just deep to the platysma muscle.
Type II: is found along the anterior surface of the sternocleidomastoid
muscle, lateral to the carotid space and posterior to the
submandibular gland.
Type III: extends medially between the bifurcation of the internal
and external carotid arteries to the lateral pharyngeal wall.
Type IV: lies in the pharyngeal mucosal space.

15.  Third and fourth branchial cleft cysts are quite rare.
 Fourth branchial cleft anomalies are usually sinus tracts which
arise from the pyriform sinus, through the thyrohyoid
membrane and descend into the mediastinum following the
tracheoesophageal groove.
 A cyst may classically develop in the superior lateral aspect of
the left thyroid gland with associated thyroiditis.

16. Second branchial
cleft cyst (arrow)
STIR MRI
-The cystic lesion at the angle of the
mandible.
-Displacing the sternocleidomastoid
muscle posteriorly,
carotid artery and jugular vein
medially and
the submandibular gland anteriorly .
The differential diagnosis will also include
cystic lymphadenopathy

17. Third branchial
cleft cyst (arrow).
T2 weighted axial MRI scan shows a
well-defined lesion in the
right posterior cervical
space which is of very high
signal onT2 (cyst)
d/d; epidermoid, lymphangioma and
cystic lymphadenopathy

18. Lymphangioma /cystic hygroma
Developmental anomaly of vasculolymphatic origin
Histological types( size of lymphatic):
cystic, cavernous, capillary and vasculolymphatic
 Present with soft, painless masses in the neck by the age of 2
years.
 The imaging findings of a uniloculated or multiloculated cystic
mass with imperceptible walls, that insinuates between vessels
and other normal structures. It is often transpatial.
 Suprahyoid neck,(#1 Loc masticator and submandibular spaces)
 Infrahyoid neck ( #1 Loc posterior cervical space)

19. CT scan of a 3-month-old infant
with a
large transpatial (parotid, carotid
and retropharyngeal space) low
attenuation cystic lesion which
crosses the midline and is
associated with airway
obstruction (endotracheal tube in
situ) in keeping with a
cystic hygroma (arrow)

20. T1WI axial MRI
(lymphangioma)
large high signal lesion
involving the parotid
space and parapharyngeal
space (arrow).
The differential would
include other
parotid space lesions

21. Dermoid & Epidermoid cysts
Both contain epithelial elements
Dermoid cyst: skin appendages within the wall.
CT : fatty internal elements, mixed density fluid and calcification.
Epidermoid cyst: Are fluid density simple cysts ( rare)
Typically involve the floor of mouth (sublingual, submandibular
spaces and the root of the tongue)

22. (a) Axial CT
low attenuation lesion seen in the right
submandibular space consistent with an
epidermoid cyst (arrow).
The differential diagnosis would include cystic lymphadenopathy.
(b) AxialT2WI
high signal lesion in the left sublingual and
submandibular spaces (arrow). Surgical
correlation showed an epidermoid cyst.
The differential would include a diving ranula

23. SagittalT1WI
high signal lesion within the nasopharynx in
an infant in keeping with a
nasopharyngeal dermoid or a hairy polyp
(arrow

24. Ranula
Rretention cyst originating from obstruction of the
sublingual or minor salivary glands usually due to
inflammation or trauma.
A simple ranula is confined to the sublingual space.
If it enlarges, the cyst extends into the
submandibular and inferior parapharyngeal space
and it is called a diving or plunging ranula.

25. (a) AxialT2WI
high signal lesion in the left sublingual space
extending to the submandibular space
consistent with a plunging ranula (arrow).
(b) AxialT1WI with gadolinium
enhancement of the same ranula showing
minor rim enhancement of the cystic lesion
(arrow)

26. Tornwaldt’s cyst

Benign developmental midline lesion on the posterior
wall of the nasopharynx between the prevertebral
muscles.
 It is related to the embryogenesis of the notochord.
 The contents are high in protein and anaerobic bacteria
making it high signal onT1 andT2 weighted images.

27. (a)An axial CTscan
small cystic lesion with atypical
calcification located in the midline of
the nasopharynx consistent with a
Tornwaldt’s cyst (arrow).
T2 WI: a small high signal well-defined lesion
in the midline of the nasopharynx.This is
again aTornwaldt’s cyst (arrow)

28. Pharyngeal mucosal space retention
cyst
 A benign epithelial lined mucosal cyst can occur within the
pharyngeal mucosal space of the nasopharynx oropharynx
and Vallecula .
 A well-defined cyst in this location is characteristic.

29. T1 weighted coronal scan:
Slight hyperintensity indicating
proteinaceous fluid or
haemorrhage within a lesion
which is off midline consistent
with a mucosal retention cyst
(arrow)

30. CT scan
Axial: shows a low density lesion in the left
vallecula.This is in keeping with a vallecular
cyst
(arrow). However, the differential diagnosis
also includes a thyroglossal duct cyst.
(b) Sagittal
the relations of the cyst within the
vallecula (arrow). Surgery
confirmed a vallecula cyst

31. Cystic lymphadenopathy
Most common causes:
 Infectious diseases, e.g.TB
 Metastatic lymph nodes:
Lymphoma,
Squamous cell CA (tonsillar SCC #1)
Papillary carcinoma

32. Axial CT
Multilocular cystic lesion with
enhancing walls
Biopsy: lymphadenopathy
D/D: Necrotic nodes from Met-SCC
Axial CT
large cystic lesion with enhancing wall (Arrow)
The enhancing mass on the left is a large carcinoma of
the tongue extending to the floor of the mouth

33. Abscess
AxialCT scan with contrast:
irregular low density lesion in the left medial
pterygoid muscle consistent with an abscess
(arrow)
Commonly occur in the submandibular,,
sublingual and masticator spaces
These often appear cystic with a variable
degree of rim enhancement both on
CT and MRI.
CT is often helpful in identifying a dental or mandibular cause.
Mastoid disease, paranasal sinus disease, suppurative lymph nodes
and congenital cysts are other potential soft tissue
inflammatory lesions presenting as cystic masses.

34. Cystic lesions in the salivary glands
(a)Axial CT scan : bilateral multiple cystic lesions in
both the deep and superficial lobes of the parotid
(Sjogren’s syndrome)
D/D :benign lymphoepithelial lesions of HIV
 Causes in Parotids: (enlarged parotid +/-
adenopathy)
 Infection, granulomatous,
 autoimmune disease e.g. Sjogren’s
syndrome) (Figure a)
 Benign lymphoepithelial lesions of HIV
(Figure b)
 Other benign (e.g.Warthin’s tumour),
 malignant (e.g. cystic intraparotid
lymphadenopathy)
 obstructive disorders (e.g. sialocoeles)
(Figure 18).

35. (a)Axial fat satT1 WI post gadolinium
low signal within the left
submandibular space with no
contrast enhancement (arrow).The
appearance is consistent with a
sialocoele.
STIR (Coronal short tau inversion
recovery ) High signal within the left
submandibular gland with septations
(arrow).
confirmed at surgery to be a
sialocoele

36. Cystic schwannoma (uncommon )
Parapharyngeal space > posterior cervical space
 Arise from the cranial, peripheral, or autonomic nerves
 Typically :cranial nerve XI, the distal brachial plexus or the cervical
sensory nerve.
 Association with neurofibromatosis

37. (a) CoronalT1 image
cystic schwannoma right perivertebral space
(arrow).
(b) STIR image from the same patient shows
a large high signal lesion in the right perivertebral space which
demonstrates a fluid–fluid level (arrow).
Excisional biopsy confirmed a cystic schwannoma

38. LOCATION ISTHE KEY!
Quick review:

39. Cyst Feature
Thyroglossal
duct cyst
Midline or paramedian
Embedded within the strap muscles
Laryngocoele arising from the laryngeal ventricle.
Change size with theValsalva manoeuvre.
Lymphangioma /cystic
hygroma
Uniloculated or multiloculated cystic mass with imperceptible walls
Usually Transpatial. (#1 Loc masticator and submandibular spaces)
Dermoid & Epidermoid
cysts
Epithelial elements,,,skin appendages within the wall OF DERMOID.
CT : fatty internal elements, mixed density fluid and calcification.
Typically involve the floor of mouth (sublingual, submandibular spaces and the root of the
tongue)
Ranula Rretention cyst sublingual or minor salivary glands (sublingual space).
Diving or plunging ranula: extends into the submandibular and inferior parapharyngeal
space
Tornwaldt’s cyst Midline lesion on the posterior wall of the nasopharynx between the prevertebral
muscles.
The contents are high in protein and anaerobic bacteria making it high signal onT1 andT2
weighted images.

40. Cysts (CONTINUED) Feature
Pharyngeal mucosal space retention
cyst
nasopharynx oropharynx and Vallecula .
Off midline
Cystic lymphadenopathy enhancing walls
Abscess enhancing walls,
submandibular,, sublingual and masticator spaces
Cystic schwannoma Parapharyngeal space > posterior cervical space
cranial nerve XI, distal brachial plexus/ cervical sensory nerve
Branchial cleft cysts
1 rst
Can be from the external auditory canal (EAC) through the parotid gland to
the submandibular region
2 nd (I & II) Anterior surface of Sterno-mastoid
(III) b/w carotid arteries & the lateral pharyngeal wall.
(IV) lies in the pharyngeal mucosal space.
3 rd (rare) posterior cervical space
4 rth (rare) Pyriform sinus, through the thyrohyoid membrane… tracheoesophageal
groove….. into the mediastinum

41. References:
CT and MRI appearances of cystic lesions in the suprahyoid, neck: a pictorial review
EKWoo*,1 and SEJ Connor2
1Department of Radiology,Guy’s Hospital, London, UK; 2Department of Neuroradiology,
King’sCollege Hospital, London, UK
Dentomaxillofacial Radiology (2007) 36, 1–9. doi: 10.1259/dmfr/69800707
 Suprahyoid Spaces of the Head and Neck, David M.Yousem
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