Head & Neck Staging: Oral Cavity & Pharynx.
Table of Contents
Outline
Cross-sectional Anatomy More Anatomy
Follow TNM and1 use for basis of template for structured reporting.
Tumour
THINK 2cm and 4cm as cut off in MAX dimension.
Always measure Depth of Invastion (DOI) for OC. Measured from presumed basal membrane inwards ie Deep. Not very accurate but correlates with the risk of Nodal disease.
Invasion into BONE: Same signal on all sequences as tumour. Cortical invasion = loss of low signal on T1 and T2. +/- CT for bony plates.
Use >270 degrees of contact as measure of invasion.
Nodes
THINK 3cm and 6cm as cut offs in MAX dimension for STAGING.
6cm is usually a conglomeration of nodes.
Use 10mm etc in maximum shortest axial dimension as cut off for INVOLVEMENT.
INVOLVEMENT
Use:
1) SIZE - in shortest AXIAL slice dimension.
1) Retropharyngeal Nodes = 5mm
2) Jugulodigastric = 11mm
3) Other = 10 mm.
4) Also 3 or more borderline = >8mm.
2) SHAPE - Round .
3) NECROSIS
4) LOSS of HILUM.
5) VASCULARITY PATTERN.
6) FUNCTION = PET / DWI
7) Also do FNAC.
Techniques are all complimentary and using >1 always improves S/S.
Assess likelihood by looking at the usual spread of nodes.
N Staging (all except NP and p16 OP)
| Nodal Stage | Number + Site | Size (Max Dim) |
|---|---|---|
| N1 | Single. Ipsilateral. | =< 3cm. No ENE |
| N2a | Single. Ipsilateral | >3 to 6cm. No ENE |
| N2b | Multiple. Ipsilateral | <6cm. No ENE |
| N2c | Bilateral or Contralateral | <6cm. No ENE |
| N3a | Any | >6cm. No ENE. |
| N3b | Any | Clinical ENE |
ENE is measured clinically BUT still look for it and call it! It is skin involvement or soft tissue invasion with deep fixation or tethering to underlying muscle or adjacent tissue. Or clinical signs of nerve involvement (CN, Brachial plexus, sympathetic trunk or phrenic nerve invasion)
Impact of N - staging.
Treatment of Nodal Disease
No technique is anything better than good, therefore combining nearly always improved S/S 1
Mets
M0 or M1 only.
<5% have detectable distant disease at presentation. ( thus no need PET ? no need PET-CT).
Lung > Bone > Liver (odd on its own).
Brain is rare at presentation.
Oral Cavity (OC)
Anatomy & Terminology
Consists of 'Subsites' =
1. Lips - mucosal surface of.
2. Anterior 2/3 of tongue. - upto the circumvallate papilla.
3. Floor of mouth - includes the sublingual spaces (SLS).
4. Buccal mucosa - lines the cheeks.
5. Gingival mucosa - overlies the upper and lower alveolar ridges of the maxilla and mandible.
6. Retromolar trigone - mucosa covering the last lower molar tooth and over the anterior ramus.
7. Palatal Mucosa
Gap between cheek & alveolar ridges = Oral Vestibule.
Oral Tongue consists of:
- Tip
- Ventral Surface (=undersurface)
- Dorsal Surface
- Lateral borders.
Tongue muscles are Intrinsic = No bony attachment. or Extrinsic = Attached to bone.
Each half has separate blood supply & innervation with Lingual septum (=raphe) which is avascular & fibrofatty.
Floor of Mouth
= Beneath mobile tongue and bounded by lower alveolar ridges. Inferior border is the Mylohyoid which separates from submental space.
Its contents are in the:
Sublingual space = Sublingual and minor salivary glands.
Submandibular (Wharton's) duct, part of Hyoglossus muscle. Lingual artery, vein and nerve as well as Hypoglossal nerve.
Pathology
90% are SCC.2 Others = minor salivary gland tumours, lymphoma, melanoma, sarcoma, odontogenic tumours, miscellaneous tumours.
Most detected early.
In West:
- Lip 40% (UV)
- Gingival & Buccal mucosa 20%
- Oral Tongue 15%
- Floor of Mouth 15%
- Hard Palate 5%
In Asia Gingival & Buccal mucosa = 75% due to Betel and tobacco chewing.
T Staging of Lip and Oral Cavity.
| Tumour | Description |
|---|---|
| Tis | Carcinoma in Situ. |
| T1 | Max dimension =<2cm + DOI =< 5mm. |
| T2 | Max =<2cm + DOI = 5 to 10mm. OR Max > 2cm to 4cm + DOI =<10mm. |
| T3 | Max >4cm OR DOI >10mm. |
| T4a | Lip: invades through Cortical bone, Inferior alveolar nerve, Floor of mouth or Skin of chin or nose. Oral Cavity: invades Cortical bone of mandible or maxilla, Maxillary sinus, or Skin of face. |
| T4b | Both: Invades Masticator space, Pterygoid plates, Skull base or encases ICA. |
Superficial erosion of the bone/tooth socket by a gingival primary is not enough to call T4.
Spread Patterns. aka Local invasion.
One way to assess HNSCC spread is to think in terms of type of tissue - so skin, soft tissue, nerves etc1
| Tumour subsite | Direction | Into | Notes |
|---|---|---|---|
| Lip | Superficial | Adjacent Skin (Chin or Nose =T4a) | |
| Posterior | Soft Tissue (FoM or Tongue Base = T4a) Nerves (Inferior Alveolar Nerve = T4a, Mental nerves) Bone (Maxilla or Mandible = T4a). |
||
| Deep | Bone (Pterygoid plate or Skull base = T4b) Muscle (Masticator space =T4b) Vessels (ICA encasement = T4b) |
||
| Buccal | Superficial | Buccinator Muscle into Buccal Fat Subcut Fat Retromolar trigone Skin (T4a) |
Buccinator spread is often early. |
| Posterior | Buccogingival sulci onto Alveolar Gingiva to Retromolar Trigone Mandibular/Max Bone (T4a) |
||
| Deep | Masticator space (T4b) Pterygoid plates or Skull base (T4b) ICA encasement (T4b) |
||
| Gingival | Lower More Common |
Buccogingival sulcus Buccal mucosa Skin of cheek (T4a) Floor of mouth Bone of mandible^^ (T4a) Inferior Alveolar Nerve (already T4a) |
Frequently superficial along mucosa. ^^ Superficial bone or early socket stuff does not affect prognosis and thus T4 stage. |
| Upper | Upper buccogingival sulcus medial to Palate mucosa Maxillary alveolar bone (T4a) Maxillary Sinus(T4a) |
||
| Deep | Masticator space (T4b) Pterygoid plates or Skull base (T4b) ICA encasement (T4b) |
||
| Retromolar Trigone | Anteromedial | Alveolar Gingiva Palate Floor of mouth Maxillary bone (T4a) |
Will spread early and rapidly At interface with OP & OC. |
| Posteromedial | Tonsil Tongue base Mandible (T4a) |
Early into mandible. | |
| Deep | Masticator space (T4b) Pterygoid plates or Skull base (T4b) ICA encasement (T4b) |
Skull base via pterygomandibular raphe. | |
| Oral Tongue | Superficial | Floor of Mouth Lower gingiva Mandible (T4a) |
|
| Posterior | Oropharyngeal tongue Hypopharynx Larynx |
||
| Deep | Masticator space (T4b) Pterygoid plates or Skull base (T4b) ICA encasement (T4b) |
Skull base via pterygomandibular raphe. | |
| Floor of Mouth | Anterior | Within SLS Crossing the midline Tongue. |
Spreads easily. |
| Lateral | Gingival mucosa Manibular bone (T4a) |
||
| Posteriorly Unusual |
Submandibular space (SMS) thru Mylohyoid muscle into Submental space Lingual nerves (??) |
||
| Deep | Masticator space (T4b) Pterygoid plates or Skull base (T4b) ICA encasement (T4b) |
Skull base via pterygomandibular raphe. | |
| Palate | Upper alveolus Soft palate Hard Palate Bone (T4a) Alveolus Bone (T4a) Nasal Cavity (T4a) Maxillary Sinus (T4a) Greater & Lesser Palatine Canals then to Pterygopalatine fossa then to Skull Base (T4b) |
Most masses here are Salivary gland and most of them benign esp Pleomorphic adenomas. Neural invasion via Palatine canals and PPF can be discontinuous = thus look carefully. |
For Surgical Planning then in Oral Tongue need to state:
1. Bulk (1/3 or more)
2. Size and Depth of invasion.
3. Min distance to Lingual NV bundle.
4. Min distance to contra Lingual NV bundle.
5. Midline Raphe: Min distance to / Involved.
6. Tongue Base / Larynx involvement.
Nodes from Oral Cavity Tumours.
Level I and II
Often bilateral esp if midline.
Also look at Retropharyngeal and Parotid.
Treatment
Depends on Location, Size and Extent.
Small = WLE or Brachy. Large / Extensive = RT, ChemoRT or Combination with surgery.
For tongue : Avoid total glossectomy and usual give ChemoRT. Normally do WLE or partial glossectomies preserving at least one lingual NV bundle.
Nasopharynx (NP)
Is the odd one and different from other HNSCC, thus has separate T staging.
Is odd in its preference for skull base & CNS invasion and its histo:
WHO Classification:
- Type I: Keratinizing SCC.
- Type II: Non-keratinizing SCC.
- Type III: Undifferentiated carcinoma.
Type III is the commonest esp in China/SE Asia & North Africa.
M>>F, 40-60yo.
EBV, diet and genetics (4x risk in 1st degree relatives).
DD: Lymphoma, Adenoid cystic & RMS
Imaging = MRI for Staging and Assessment.
RT Planning.
Also DIAGNOSIS = 10% are occult on endoscopy, mostly small ones tucked into FOSSA OF ROSENMULLER.
T - Staging of NPCs.
| Tumour | Description |
|---|---|
| T1 | Confined to Nasophaynx or Oropharynx and/or Nasal Cavity |
| T2 | Parapharyngeal space and/or Medial Pterygoid Muscle or Lateral Pterygoid Muscle |
| T3 | Bony Structures of: - Skull base - Vertebrae - Pterygoid structures - Paranasal sinuses |
| T4 | Intracranial Extension Cranial Nerve involvement Hypopharynx Orbit Parotid Gland Beyond lateral surface of lateral Pterygoid (infratemporal fossa?) |
Notes on T - Staging of NPCs
T1
Is still T1 if it involves the Levator palatini muscle attached to the tube, or the Eustachian tube entrance.
NPC prefers to go Superiorly into nasal cavity than Inferiorly into Oropharynx.
T2
Here it invades:
- Parapharyngeal fat.
- Tensor Palatini muscle.
- Medial and Lateral Pterygoid muscles.
- Carotid Sheath.
Pharyngobasilar Fascia = Thin black line along lateral & posterolateral aspects of NP.
Posteriorly => Retropharynx.
Here it invades:
- Preclival / Prevertebral muscles
- Prevertebral Fat & fascia.
- Venous Plexus ( Batson's venous plexus ).
Spreads preferentially down the retropharynx to the cervical level.
T3
Is where it starts to invade the skull base.
Assessment can be remembered as ( and important to report as ):
A. THREE MAJOR BONY SITES
-- Pterygoids (medial part not protected by fascia)
-- Clivus
-- Petrous Apices
Which all fit in on one Ax T1 slice. Find this then check in MPR.
Everyone writes this up as 5 but 2 are bilateral and bilaterality is ignored elsewhere.
B. THREE MAJOR FORAMINA
-- Foramen Rotundum ( Vii nerve / Maxillary )
-- Foramen Ovale ( Viii nerve / Mandibular )
-- Foramen Lacerum ( Lots inc. Pterygoid Canal Artery, Pterygoid canal Nerve = Greater & Deep Petrosal Nerves, Terminal branch of Ascending Pharyngeal Artery).
Best seen on Coronals. Foramen Lacerum runs beneath the horizontal part of the ICA Others include Sphenopalatine, jugular foramen and foramen spinosum
C. THREE MAJOR CANALS
-- Vidian Canal ( Vidian nerve, from PPF to Foramen Lacerum )
-- Pterygopalatine Canal ( Greater and lesser Palatine nerves runs downwards to Palate)
-- Hypoglossal Canal ( XII and a venous plexus ).
Enhancement on its own and symmetrically in the Hypoglossal canal is not tumour but venous. Others to consider but less often are Infraorbital ( Vii perineural spread ) & Optic Canal.
D. THREE MAJOR FISSURES
-- Pterygomaxillary Fissure ( Posterior wall of Maxillary Sinus )
-- Orbital Fissures (Both superior and Inferior )
-- Petroclival Fissure ( between Clivus and Petrous Apex)
E. ONE MAJOR FOSSA
-- Pterygopalatine Fossa
- Contains Vii and Pterygopalatine ganglion.
- Located at medial end of pterygomaxillary fissure and behind the Maxillary sinus.
- DANGER ZONE as can spread from here into:
1. Medial wall of nasal cavity ( via Sphenopalatine foramen ).
2. Infratemporal Fossa ( via Pterygomaxillary fissure ).
3. Orbit ( via IOF ).
4. Brain ( via Foramen Rotundum Vii )
5. ICA ( via Vidian canal )
6. Palate ( via Pterygopalatine Canal )
Also remember to mention:
1. Cervical Spine
2. Paranasal Sinuses.
T4
BRAIN & CRANIAL NERVES
- Mostly by Cavernous Sinus ( via bone, foraminae, ICA or nerves )
- or Dura of Middle and Posterior Fossa.
- Perineural involvement most often:
-- Vii in Infraorbital Canal.
-- Viii in Parapharyngeal Fat space.
Also look out for VII and the communicators with V + VII = Auriculotemporal N. communicates Viii to VII in Parotid.
Look for signs of muscle denervation in Mastication -> Viii or Hemitongue -> XII.
INFRATEMPORAL FOSSA
- Space anterolateral to Lateral Pterygoid muscle.
- Usually invaded by pterygomaxillary fissue (via PPF ) or through the lateral pterygoid.
ORBIT, PAROTID & HYPOPHARYNX
- Orbit invaded by the orbtial fissures & optic canal from cavernous sinus or PPF.
- Hypopharynx is rare.
N Staging
Criteria for involvement are the same but the staging is different.
Spreads to nodes with ease; often big nodes but tiny primary.
Level II & Retropharyngeal Nodes.
Then follow the chains to III,IV or VA,VB.
Medial retropharygeal nodes not very well defined - more of a plaque like level of enhancement.
Bilateral is common. Freq large, necrotic, ENE.
N3 is best imaging predictor for advanced disease.
| Nodal Stage | Number + Site | Size (Max Dim) |
|---|---|---|
| N1 | Unilateral Neck or Uni / bilateral Retropharyngeal. |
=<6cm above distal border of cricoid. |
| N2 | Bilateral | =<6cm above distal border of cricoid. |
| N3 | Any neck nodes | >6cm or Extend below caudal border of Cricoid. |
Treatment
Mostly RT. Little role for Surgery. Chemo for downstaging large (neoadj) and then ChemoRT.
Most often Cis/5FU or Cetuximab (eGFR receptor inhibitor). Immuno = Nivo and Pembro as well.
NeoAdj systemic therapy does not improve OS but aids local control
Oropharynx (OP)
Only site at present using HPV status as a guide. Uses P16 tumour suppression gene overexpression on immunohistochemistry as a surrogate for HPV status. ( Cheap, widely available, cheap ) HPV subtyping via in-situ hybridisation is also then carried out.
p16 tumours are generally smaller but with more advanced nodes than p16 negative.
Nearly all SCC.
Salivary gland malignancies - Adenoid cystic & Mucoepidermoid carcinoma - Uncommon. Tend to be higher T2.
Soft palate frequently have Pleomorphic adenomas.
T - Staging of Oropharyngeal Tumours
| Tumour | Description |
|---|---|
| Tis | Carcinoma in situ |
| T1 | Max Dimension < 2cm |
| T2 | Max Dimension >2cm to 4cm |
| T3 | Max Dimension >4cm OR, Extends to mucosa of epiglottis if primary is Tongue base or Vallecula. |
| T4a | Tumour invades: - Larynx - Deep muscles or Extrinsic muscles of tongue (=Genioglossus, Hyoglossus, Palatoglossus,Styloglossus) - Medial Pterygoid muscle - Hard Palate - Mandible. |
| T4b | Tumour invases: - Lateral pterygoid muscle - Pterygoid plates - Lateral Nasopharynx - Skull Base - Encases the Carotid artery. |
For p16/HPV SCC then T4a and T4b are combined as T4a.
Spread Patterns aka Local Invasion.
NB: Submucosal spread is common and difficult to clinically assess.
| Tumour subsite | Direction | Into | Notes |
|---|---|---|---|
| Tongue Base | Deep | Extrinsic Tongue Muscles (T4a) --Genioglossus --Hyoglossus |
Esp these 2 muscles. |
| Posterior | Tonsil via glossotonsillar sulcus | ||
| Anterolateral | Floor of Mouth then into Mandible(T4a) |
||
| Vallecula | Superficial | Epiglottis (Mucosa=T3) but can go deep to Laryngeal Surface of Epiglottis(T4a) or Pre-epiglottic space (T4a) |
Initial spread to epiglottis is easily seen clinically but the later deep invasion is only seen on imaging. |
| Tonsillar Base | Local | Tongue Base Soft Palate Retromolar Trigone Posterior oropharyngeal wall. |
Arise mostly on Anterior Pillar. Can grow big and just be local. |
| Extrapharyngeal Laterally |
Constrictor muscle Medial Pterygoid (T4b) lateral to Parapharyngeal Space then to Carotid Artery/Space (T4b). |
||
| Superior | 1. mucosally Nasopharynx (+/-T4b) 2. deep in parapharyngeal fat to Skull Base(T4b) |
Uncommon. | |
| Soft Palate | Tonsil Hard Palate(T4a) |
Often cross midline. | |
| Superiorly | 1. mucosally Nasopharynx(+/-T4b) 2. deep along veli palatini to Skull Base(T4b) |
Uncommon | |
| Posterior Oropharyngeal Wall | Submucosal | Oropharynx Hypopharynx |
|
| Deep | Parapharyngeal Fat Prevertebral Muscles |
Parapharyngeal invasion is common. Prevertebral Muscle invasion is uncommon but poor. |
Tumours at junction of soft and hard palate may extend into perineurally within the Palatine glands
NB: Prevertebral invasion is difficult with high NPV but low PPV thus - Intact fat plane pre the muscles = NO invasion. - Loss of fat plane OR abnormal signal/thickening/enhancement = UNSURE. May need surgical assessment to see if it is resectable.
Nodes from OP tumours.
Level II Look for RP esp from Tonsil & Palatal. Bilateral common in midline.
Treatment
Early = Surgery or RT.
Advanced = ( RT or ChemoRT ) +/- Surgery.
RT generally better than Surgery for function preservation ( speech, swallowing, airway ) but long-term effects are real.
But minimally invasive techniques are beginning to show similar Outcomes to RT
for TORS (Transoral Robotic Surgery) and TLM (Transoral Laser Microsurgery)
For HPV-associated Tumours then trials of modified therapies are ongoing.
Hypopharynx (HP)
Uncommon. But masses here nearly always are SCCs.
Mostly Piriform Sinuses. (75%)
60% involve more than one subsite at diagnosis.
Can be very shallow.
Not written much about this as it is not common.
T - Staging
| Tumour | Description | Notes |
|---|---|---|
| T1 | Limited to 1 subsite and Max dimension <2cm. |
Subsites are: - Piriform Sinuses. - Postcricoid - Posterior Hypopharyngeal Wall. |
| T2 | More than one subsite or Max dimension >2 to 4cm and No fixation of hemilarynx |
|
| T3 | Max dimension >4cm or Fixation of hemilarynx. |
|
| T4a | Invades: - Cricoid / Thyroid Cartilage - Hyoid Bone - Thyroid Gland - Oesophagus - Central compartment soft tissue. |
|
| T4b | Invades: - Prevertebral Fascia - Encasing Carotid - Invading mediastinal structures. |
NB Sclerosis of Arytenoid or Cricoid cartilage is non-specific and might be reactive.
Treatment
Early T1/T2 = RT (upto 70Gy)
or Surgery with/without preop RT.
Advanced = Resect with partial or total laryngopharyngectomy if poss.
If not then RT or ChemoRT.
Treatment of Metastatic NODES.
Based on combination of RT, Surg & Chemo (Adj & Neoadj).
Often depends on the 1ry.
Surgery
= 'Neck Dissection' = Aim to remove involved OR at-risk nodal groups.
For Clinical NODE POSITIVE without adverse features.
1) Radical Neck Dissection = en-bloc removal of unilateral.
-- Levels I - V nodes.
-- SCM Muscles
-- IJV
-- SMG
-- Spinal Acc N.
2) Modified Neck Dissection = more common.
-- Levels I - V nodes.
But leave behind leave behind one or more of the above structures.
For No Clinical / Rad features of positive but HIGH - RISK of occult (>20%)
Which is most of them apart from low T stage glottic and some Low T stage OC.
1) Selective or Functional Neck Dissection.
- 1 or more nodal groups preserved.
- Supraomohyoid Neck Dissection = Remove I - III. Used for Low T stage OC Ca.
Often followed by ChemoRT if adverse histo post-resection.
Second Primary
Synchronous in <6mths. = 1 to 6%
Most likely in HP or Laryngeal.
Site of Second primary include Lung and Oesophagus as well as the head and neck.
Post-Treatment Imaging.
Radiotherapy
Early
- Mucositis.
- Diffuse mucosal thickening.
- ^^ T2.
- +/++ Gd.
- Thickening of skin / platysma
- Reticulation of fat.
- Salivary gland changes.
Late
- Atrophy
- Salivary glands, nodes, lymphoid tissue.
- Muscles inc Platysma, Pterygoids, Constrictors
- Thickening of skin ( + signal change )
- Scar
- vv T2.
- -/+ Gd.
The changes stabilise by 18 months apart from scarring which can go on for years.
Surgery
Often lots of resection then reconstruction using Flaps
may involve skin, fascia, fat, muscle and bone.
- 'Local' = flap transferred from local tissue.
- 'Pedicled' = harvested on a paddle & moved/rotated with the native blood supply left in situ.
- 'Free Flap' = vessels are anastomosed to the in-situ vessels.
So, for
1) Laryngopharyngectomy
Pedicled musculocutaneous flap from Pec major. This gets around the limited blood supply
in post RT tissues.
Rad: Bulky tissues with muscle -> Denervation -> Fatty Atrophy.
2) Oral Cavity / Pharynx
Radial Forearm Free Flap is most common.
Others include - Rectus abdominis myocutaneous, Lateral arm, Anterior lateral thigh,
Iliac crest, Fibula free flaps.
Jejunal flaps - used for pharynx and pharyngo-oesophageal recon.
Post-Treatment Imaging & Surveillance
Very early stage disease = no point follow clinically.
Normally most patients are followed clnically carefully & regularly.
-
Imaging: Usually MR or CT 3 to 6 months post- completion to allow regression to occur ( esp to RT ). The appearances at this stage predicts outcome. If complete reduction in abnormal signal then very good. But thickening increases the probability of relapse. This is especially true for larynx / hypopharyngeal tumour.
-
PET-CT at 2-3 months, NPV = 0.97 . But, the PPV is much worse.
-
Long - term Surveillance = little good evidence. But 25% recur in < 2y. Mostly local or regional. Close clinical FU for 2ys. Most high-risk relapse patients have CT/MRI 3-6 mthly for 2yrs. No agreement for matachronous or other tumours.
Post-Treatment Complications.
1) Osteoradionecrosis.
Radiology:
-- Sclerosis
-- Cortical & Cancellous destruction.
-- Sequestration.
-- Path #
-- Soft tissue thickening
-- Fistula formation.
-- Gd ++ so diff to diff from recurrence.
- FDG not helpful as ORN is +ve FDG.
- Mandible = if findings distal to primary site then likely to be ORN not Rec.
2) Chondronecrosis.
-- Can be very similar to recurrence.
-- Gas suggests necrosis not recurrence.
3) Radiotherapy - induced Fibrosis
=> Dysfunction =>
-- Aspiration
-- Dysphagia due to stenosis.
4) Other Radiotherapy - related.
-- Arteriopathy
-- WM / GM injury
-- Necrosis
-- Radiation induced myelopathy
-- CN palsy.
-- Salivary gland injury
-- Radiation induced tumours inc SCC and Sarcoma.