01 - Radiol Clin N Am 2007 - Oral Cavity and Oropharynx Tumors.pdf - książki - Bio Med 21 - bibiariel

RADIOLOGIC

CLINICS

OF NORTH AMERICA

Radiol Clin N Am 45 (2007) 1–20

Oral Cavity and Oropharynx Tumors

Hilda E. Stambuk, MD a, *, Sasan Karimi, MD a ,

Nancy Lee, MD b ,SnehalG.Patel, MD c

- Oral cavity

Screening

Diagnosis

Staging

Disease-speciﬁc follow-up

- Oropharynx

Diagnosis

Staging

Disease-speciﬁc follow-up

- Summary

- References

Cancers of the oral cavity and pharynx are the

most common head and neck cancers in the United

States [1] . Most tumors are squamous cell carcino-

mas (SCC), but other histologic types may include

minor salivary gland carcinomas and, rarely, lym-

phomas and melanoma. For descriptive purposes,

the mucosa of the oral cavity and oropharynx is di-

vided into several anatomic sub sites ( Fig. 1 ). The

anatomic division between the oral cavity and

oropharynx is artiﬁcial, and in actual practice it is

not uncommon for a tumor to cross over into the

oropharynx from the oral cavity and vice versa.

The clinical behavior of tumors in these two loca-

tions is distinct, however. As a general rule, regional

lymph node and distant metastases are more fre-

quently observed with involvement of the orophar-

ynx by SCC. Clinical behavior is also dictated by the

histologic type of tumor; perineural spread of dis-

ease and lung metastases are features associated

with adenoid cystic carcinoma of minor salivary

gland origin. Clinical examination and evaluation

of local extent of disease are easier in the oral cavity

because the mucosa of the oral cavity is more easily

accessible to clinicians for clinical inspection and

palpation. It is important for clinicians and radiol-

ogists to understand these differences in clinical be-

havior to direct patients to appropriate imaging in

the initial evaluation and subsequent follow-up of

their disease. Radiologic issues pertaining to these

two anatomic sites are discussed under two separate

sections in this article. The focus is on SCC, but rare

tumors such as adenoid cystic carcinoma are men-

tioned brieﬂy where appropriate.

Oral cavity

Screening

Clinical examination of the oral cavity is superior to

radiologic imaging in assessing for mucosal lesions.

There is no cost-effective role for imaging in screen-

ing for index primary lesions of the oral cavity, even

in selected high-risk populations. Patients who

have SCC of the oral cavity are at a small but

deﬁned risk for synchronous primary tumors

[2,3] . Although most of these second primary

tumors occur in the oral cavity and are easily

detected on clinical examination, a second primary

can be missed in patients who are difﬁcult to

a Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY

10021, USA

b Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New

York, NY 10021, USA

c Department of Surgery, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021,

USA

* Corresponding author.

doi:10.1016/j.rcl.2006.10.010

radiologic.theclinics.com

Stambuk et al

Fig. 1. The anatomic sub sites of the oral cavity, (oral tongue, ﬂoor of mouth, lower alveolus, retromolar trigone,

upper alveolus, hard palate, buccal mucosa), and oropharynx (base of tongue, soft palate, palatine tonsil).

(Courtesy of Memorial Sloan-Kettering Cancer Center, New York, NY; with permission.)

examine because of pain or trismus. The radiologist

automatically should survey the upper aerodiges-

tive tract for additional tumors when imaging stud-

ies have been ordered for staging any oral cancer.

Incidental discovery of a synchronous primary tu-

mor may result in modiﬁcation of the treatment

plan in a patient who is being evaluated for a known

oral cavity primary ( Fig. 2 ).

that can impact treatment. It is important to be

aware of certain common imaging characteristics

that might help in differentiating benign from ma-

lignant lesions of the oral cavity ( Table 1 ). SCC gen-

erally only mildly enhances postcontrast on CT

imaging and can be subtle ( Fig. 3 ). On MR imaging

scans, SCC is isointense to muscle on T1-weighted

images, tends to be of high T2 signal, and generally

exhibits mild to moderate homogeneous enhance-

ment. CT is the more common imaging modality

in the evaluation of oral cavity cancers. CT imaging

of the oral cavity and neck with contrast can be ac-

quired within minutes with modern multidetector

scanners, and the raw data easily can be used for

coronal and sagittal reformation. CT is superior in

evaluating the mandible for cortical bone invasion.

Diagnosis

Most patients who have SCC come to imaging with

the diagnosis already made. The role of imaging as

a diagnostic modality is limited. The radiologist

should not be satisﬁed with identifying the tumor

alone but should provide the clinician with infor-

mation about the local extent and regional spread

Fig. 2. (A) The patient presented with a clinically evident SCC of the left retromolar trigone (arrow) for which

a CT scan of the oral cavity was performed. (B) Incidental right base of tongue primary cancer (arrowhead)

was discovered at imaging.

Oral Cavity and Oropharynx Tumors 3

Table 1: Imaging characteristics of benign versus malignant tumors of the oral cavity

Benign

Malignant

Location

Generally deep

Generally superﬁcial

Conﬁguration

Well deﬁned

Ill deﬁned

Surrounding tissue

Normal or may be

displaced

Invaded

Internal characteristics

Fatty, cystic or vascular

ﬂow voids but can be

heterogeneous or solid

Solid and isodense to

muscle MR imaging;

T1-weighted isointense,

T2-weighted

hyperintense to muscle,

variable enhancement

Calciﬁcations

No calciﬁcations

Bone

Not affected or

regressively remodeled

Cortical invasion or

destruction

Nerves

Not affected or focal

lesion if benign nerve

tumor

Perineural spread is

generally diffuse or

skips with associated

oral cavity mass

FDG-PET scan

Generally no FDG

uptake except in

infection

1 FDG uptake except in

tumors of minor salivary

gland origin

MR imaging can be helpful in evaluating the full

extent of medullary cavity involvement once the

mandibular cortex has been violated. MR imaging

is the imaging modality of choice in the evaluation

of hard palate tumors, where replacement of bone

marrow by tumor is more easily appreciated on pre-

contrast T1-weighted images ( Fig. 4 ).

CT can be limiting in the evaluation of oral cavity

tumors because of beam hardening artifact from

dental work. Susceptibility artifact from dental

work is generally less obscuring of the underlying

anatomy on MR imaging than the artifact created

with CT scanning. MR imaging shows superior

tumor/muscle interface and better delineates peri-

neural spread of disease; however, it is limited by

its long acquisition time. An adequate MR imaging

of the oral cavity takes approximately 30 minutes to

acquire, with imaging of the neck requiring another

30 minutes. Patients who have bulky tumors of the

oral cavity have pooling of secretions and constant

swallowing, which can render an MR imaging

examination nondiagnostic.

Fig. 3. Contrast-enhanced CT scan of the oral cavity.

Note that tumor in left ﬂoor of mouth (arrow)is

only mildly enhancing and relatively isodense to sur-

rounding muscle.

Fig. 4. Sagittal precontrast T1-weighted image shows

bone marrow invasion by adjacent mucosal hard pal-

ate adenoid cystic carcinoma. The normal higher sig-

nal fatty marrow is replaced by grayish appearing

tumor (arrow).

Stambuk et al

The presence of nodal metastases is the most sig-

niﬁcant predictor of adverse outcome in head and

neck SCC [4] . Extracapsular spread of disease

from a metastatic lymph node worsens the progno-

sis further, and these patients may beneﬁt from

more aggressive treatment [5,6] . CT shows focal

nodal metastases/necrosis in ‘‘normal sized’’ lymph

nodes and extracapsular spread of disease from

lymph nodes sooner than MR imaging and before

it becomes apparent on clinical examination

( Fig. 5 ).

imaging, but CT is the workhorse. MR imaging of-

ten complements CT and should be used to exam-

ine speciﬁc questions, such as perineural spread of

disease. If a patient is able to lie still without swal-

lowing or moving, MR imaging provides better

delineation of tumor from muscle. MR imaging is

especially useful in the evaluation of extent of in-

volvement of the musculature of the tongue, which

can be difﬁcult to evaluate on clinical examination

in an awake patient. The precise delineation of local

extent of tumor not only is important for assigning

T stage ( Table 2 ) but also is crucial in treatment

planning.

CT must be performed with intravenous contrast

to better identify the primary tumor and help differ-

entiate nodal metastases from adjacent vasculature.

These images should be provided in axial and coro-

nal planes in standard and bone algorithms for

complete evaluation of the soft tissues and bone.

MR imaging scans always should be performed

with and without gadolinium intravenous contrast.

The precontrast T1-weighted sequence is particu-

larly useful in differentiating tumor from surround-

ing fat, detecting neurovascular bundle encasement

Staging

SCC of the oral cavity tends to spread locally with

invasion of surrounding structures, and the risk

and patterns of lymphatic spread to regional cervi-

cal nodes vary with the anatomic location of the

primary tumor. Certain anatomic subsites, such as

the oral tongue and ﬂoor of the mouth, are rich

in lymphatics, and tumors of these areas have

a higher risk of nodal metastases compared with

other locations, such as the upper gum and hard

palate. Distant metastasis is not common in

patients with oral SCC, but tumors such as adenoid

cystic carcinoma have a higher predilection for

pulmonary metastases. Knowledge of the behavior

and patterns of spread of these tumors is essential

for radiologists in accurate interpretation and stag-

ing. The TNM staging system is used for epithelial

tumors, including SCC and minor salivary gland

carcinoma only [7] .

Table 2: T staging of oral cavity tumors

Primary tumor cannot be

assessed

No evidence of primary

tumor

Tis

Carcinoma in situ

T stage

The anatomic imaging techniques of choice for

local staging are contrast-enhanced CT and MR

Tumor 2 cm or less in

greatest dimension

Tumor more than 2 cm

but not more than 4 cm in

greatest dimension

Tumor more than 4 cm in

greatest dimension

T4a

Lip

Tumor invades through

cortical bone, inferior

alveolar nerve, ﬂoor of

mouth, or skin of face (ie,

chin or nose)

Oral Cavity

Tumor invades through

cortical bone, into deep

(extrinsic) muscle of

tongue (genioglossus,

hyoglossus,

palatoglossus, and

styloglossus), maxillary

sinus, or skin of face

T4b

Tumor involves

masticator space,

pterygoid plates, or skull

base and/or encases

internal carotid artery

Fig. 5. Focal low density within a normal sized lymph

node (arrow) on postcontrast CT scan indicates meta-

static disease.

Oral Cavity and Oropharynx Tumors 5

(sublingual space), and detecting marrow involve-

ment of the adjacent mandible and maxilla. Sagittal

T2-weighted images can be helpful in assessing

depth of invasion of the primary tumor of the

oral tongue. The depth of invasion of the primary

tumor has been shown to correlate with the risk

for nodal metastases and outcome [8] . Postcontrast

fat saturation T1-weighted images also can be help-

ful in differentiating tumor from adjacent muscle/

fat and detecting perineural spread of disease.

Tumors with an inﬁltrative border can be differenti-

ated from those with a deﬁned ‘‘pushing’’ border on

imaging, and this information is helpful to clini-

cians in predicting outcome [9] .

Advanced lip cancers that occur along the muco-

sal surface may abut the buccal cortex of the mandi-

ble and may require CT imaging to assess the

integrity of the mandible. Imaging also may be

helpful in evaluating for perineural spread of

tumor, especially adenoid cystic carcinoma along

the mental and inferior alveolar nerves. Otherwise,

mucosal lip cancers do not require diagnostic imag-

ing for assessment of local extension.

Most cases of oral tongue SCC are located along

its lateral border or ventral surface. The prognosis

of these tumors depends on their depth of invasion.

Although superﬁcial tumors are difﬁcult to assess

on radiologic imaging, involvement of the extrinsic

muscles of the tongue (genioglossus, hyoglossus,

palatoglossus, and styloglossus) is relatively easy

to detect ( Fig. 6 ). Another feature of interest is

whether the tumor approaches or crosses the

midline ﬁbrofatty septum of the tongue. Posterior

extension of an oral tongue tumor into the base

of tongue should be noted because this ﬁnding

has the potential to change treatment. Oral tongue

SCC commonly extends into the ﬂoor of mouth.

The neurovascular bundle (particularly the lingual

artery and hypoglossal nerve and their branches)

traverses the sublingual space and can be in close

proximity to tumor ( Fig. 7 ). Surgical excision of a le-

sion such as this requires sacriﬁce of the ipsilateral

neurovascular bundle but leaves viable remnant

tongue based on the intact contralateral neurovas-

cular bundle. In contrast, if an oral tongue tumor

is extensive enough to require surgical sacriﬁce of

both neurovascular bundles ( Fig. 8 ), the patient

would require total glossectomy, which can be

functionally crippling. Nonsurgical management

(radiation with or without chemotherapy) should

be considered in these situations. Tumors of the

anterior ﬂoor of mouth can obstruct the openings

of the Wharton’s ducts (submandibular salivary

gland ducts). Radiologically evident dilatation of

Wharton’s ducts should prompt a thorough search

for a mucosal primary tumor in the absence of

obvious calculous disease ( Fig. 9 ).

Fig. 6. CT imaging shows obvious SCC involvement of

the extrinsic muscles of the tongue, including the

paired genioglossus muscles (arrows).

Evaluation of the mandible for invasion by

tumor is an important consideration in staging

and treatment planning. Tumors at certain loca-

tions, such as the ﬂoor of mouth, retromolar trig-

one, and the lower alveolus, can invade the

mandible directly. Although gross invasion is rela-

tively easy to identify, early cortical bone loss di-

rectly adjacent to obvious tumor should be

considered indicative of bone invasion ( Fig. 10 ).

If bone invasion is present, it is important for the

radiologist to deﬁne its extent so that the surgeon

is able to determine the extent of mandibular resec-

tion. In most situations CT is adequate for this de-

termination, but the bone marrow may be further

characterized by MR imaging if appropriate.

Fig. 7. CT of the oral cavity shows tumor of the right

lateral tongue (arrow) in close proximity to but

not involving the right neurovascular bundle

(arrowhead).

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