22 Korean J Radiol 6(1), March 2005

CT and MR Imaging of the Buccal Space:Normal Anatomy and Abnormalities

The buccal space is an anatomical compartment lying anterior to the masticatorspace and lateral to the buccinator muscle. Since the major purpose of imaging isto define the likely anatomic origin and also the extent of a given lesion, thoroughknowledge of the normal anatomy of the buccal space is essential, and thisknowledge can aid the physician in narrowing down the list of possible maladieson the differential diagnosis. We illustrate here in this paper the importantanatomic landmarks and typical pathologic conditions of the buccal space suchas the developmental lesions and the neoplastic lesions. Knowledge of theexpected pathologic conditions is useful for the radiologist when interpretingfacial CT and MR images.

he buccal space is located lateral to the buccinator muscle and deep to thezygomaticus major muscle (1). This space is filled with adipose tissue(termed the buccal fat pad), the parotid duct, the facial artery and vein,

lymphatic channels, the minor salivary glands and the branches of the facial andmandibular nerves. Patients suffering with the buccal space lesions usually present witha cheek mass or facial swelling. Although a variety of lesions are known to occur withinthis space, their radiological features have not been well covered in the literature. Sincethe possible diagnosis of these masses is effectively limited to a narrow range of diseasesif their compartment of origin is known, it is important to know the normal anatomyand common diseases of the buccal space. In this article, we illustrate the importantanatomic landmarks and typical pathologic conditions of the buccal space.

NORMAL ANATOMY

The buccal space’s (Fig. 1) anatomical boundaries are the buccinator musclemedially, the superficial layer of the deep cervical fascia and the muscles of facialexpression laterally and anteriorly, and the masseter muscle, mandible, lateral andmedial pterygoid muscles and the parotid gland posteriorly (1). The buccinator muscleoriginates from the alveolar processes of the maxilla and the mandible, and it insertsinto the pterygomandibular raphe. The buccal space frequently communicates posteri-orly with the masticator space because the parotidomasseteric fascia is sometimesincomplete along its medial course where it joins the buccopharyngeal fascia. There isno true superior or inferior boundary of the buccal space.

The greater part of the space is filled by adipose tissue that has been termed as thebuccal fat pad. The buccal fat pad has four projections away from the more centralbody of adipose tissue. The lateral projection follows the parotid duct posteriorly to lieadjacent to the anterolateral portion of the superficial lobe of the parotid gland. The

Hyo-Cheol Kim, MDMoon Hee Han, MDMin Hoan Moon, MDJi Hoon Kim, MDIn-One Kim, MDKee-Hyun Chang, MD

Index terms:Magnatic resonance (CT)Computed tomography (MR)Buccal spaceFace

Korean J Radiol 2005;6:22-30Received June 6, 2004; accepted after revision January 27, 2005.

Department of Radiology, Seoul NationalUniversity College of Medicine, Instituteof Radiation Medicine, SNUMRC, andClinical Research Institute, SeoulNational University Hospital

Address reprint requests to:Moon Hee Han, MD, Department ofRadiology, Seoul National UniversityHospital, 28 Yongon-dong, Chongno-gu,Seoul 110-744, Korea.Tel. (822) 760-2584Fax. (822) 743-6385e-mail: hanmh@radcom.snu.ac.kr

T

buccal fat pad extends medially between the mandible andmaxillary sinus, and it frequently communicates with fat inthe masticator space. The anterior portion of the buccal fatpad extends anterior to the parotid duct and the facialvein. The superior temporal extensions of the buccal fatare divided into the deep and superficial subdivisions withrespect to the temporal muscle. The main duct of theparotid gland (Stenson’s duct) courses in a transversefashion through the buccal fat pad, and it pierces thebuccinator muscle opposite the second maxillary molar.This parotid duct separates the buccal space into twoequal-sized anterior and posterior compartments. The CT

attenuation of the posterior compartment has beenreported to be less than that of the fat in the anteriorcompartment and in the adjacent spaces (1).

The other contents include the parotid duct, the minorsalivary glands, accessory parotid lobules, facial, andbuccal arteries, facial vein, lymphatic channels and thebranches of the facial and mandibular nerves. The facialvein is typically identified on cross-sectional images asbeing located along the lateral margin of the buccinatormuscle, just anterior to Stenson’s duct.

When tumor or infection is involved in the buccal space,the buccal space can serve as a conduit for spreading

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Korean J Radiol 6(1), March 2005 23

C DFig. 1. The normal anatomy of the buccal space.A. A transverse enhanced CT scan at the level of the upper buccal space shows the lateral projection (open arrow) of buccal fat lateral tothe masseter muscle and the medial projection (M) of buccal fat between the masseter muscle and the maxilla. The posterior extent ofthe medial buccal fat pad is limited by the lateral pterygoid muscle (T) and the overlying fascia. The origin of the buccinator muscle isseen on the right side (black arrowhead). The facial vein (curved arrow) is seen located within the buccal space. The facial artery (longarrow), buccal artery (short arrow), and zygomaticus muscle (white arrowhead) are noted.B. A transverse enhanced CT scan at the level of the middle buccal space shows the parotid duct (short arrows) coursing through thebuccal space. The angular portion of the facial vein (arrow) and facial artery (arrowhead) are located anterior to the duct. The buccinatormuscle (black arrowheads) is also noted.C. A transverse T2-weighted MR image at the level of the lower buccal space shows the buccinator muscle (arrow) having a low signalintensity and the submucosal fat pad (arrowheads) having a high signal intensity. The insertion of the buccinator muscle on the pterygo-mandibular raphe (open arrow) is also visible at this level. The facial vein (arrowhead) appears as a signal void.D. A coronal enhanced T1-weighted MR image shows the parotid duct (arrow), facial vein (arrowhead), and buccinator muscle. The deepportion of the buccal fat pad (P) lies between the temporal muscle (T) and the maxillary sinus.

A B

desease between the mouth and the parotid gland. Thelack of fascial compartmentalization in the superior,inferior and posterior directions permits the spread ofpathology both to and from the buccal space (2).

ABNORMALITIES

A variety of diseases are known to occur within thebuccal space, including developmental lesions, infectionand inflammation, neoplastic lesions and other miscella-neous conditions. Accessory parotid tissue, congenitalfistula of the parotid duct, dermoid cyst and vascularlesions such as hemangioma and vascular malformation arecommon developmental lesions found in this location (2).The most common tumor of the buccal space are minorsalivary gland tumors such as pleomorphic adenoma,adenoid cystic carcinoma, acinic cell carcinoma andmucoepidermoid carcinoma (2 4). The other tumors arethose originating from muscular, neural, connective andlymphatic tissues, and these include rhabdomyoma,rhabdomyosarcoma, neurofibroma, schwannoma, lipoma,liposarcoma, lymphoma, and metastatic lymphadenopathy.Various miscellaneous conditions would include Kimuradisease and foreign body granulomas.

DEVELOPMENTAL LESIONS

Accessory Parotid TissueIn approximately 20% of the population, accessory

parotid tissue is present in the buccal space, and this isusually just anterior to the parotid gland hilum, overlyingthe anterior margin of the masseter muscle (2). Accessoryparotid tissue (Fig. 2) is identified by CT more often thanby using MR imaging (1). Accessory parotid tissue may be

unilateral or bilateral and it is histologically and physiologi-cally identical to the tissue in the main parotid gland.

Dermoid CystSimple dermoid cysts typically appear as low-density,

well-circumscribed, thin-walled unilocular cystic masses onCT (2). Compound dermoid cysts have a more variableappearance such as a fat-fluid level or as a fat globule, andthey may have high signal intensity on T1-weighted imagesdepending on their lipid content (2). When complicated byinfection, their discrimination from abscess can be impossi-ble (Fig. 3).

HemangiomaHemangiomas are neoplastic lesions and they exhibit the

increased proliferation and turnover of endothelial cells

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Fig. 2. Bilateral accessory parotid tissues in a 59-year-old man.A transverse enhanced CT scan shows the bilateral accessoryparotid tissues (arrows), which have the same attenuation as thetissue in the main parotid gland.

Fig. 3. Infected dermoid cyst in a 3-year-old girl.A coronal enhanced T1-weighted MR image shows the cysticmass (thin arrow) in the left buccal space. The mass has anirregular margin and it has infiltrated into the surrounding buccalfat pad. Note the thickening of the superficial muscles of facialexpression and the investing fascia (thick arrow).

Fig. 4. Hemangioma in a 5-year-old girl.A transverse T2-weighted MR image shows an irregular mass(arrows) having high signal intensity involving the buccal spaceand the masticator space.

(5). Although they are rarely present at birth,hemangiomas typically become apparent during the firstmonth of life, they rapidly enlarge and ultimately involute

by adolescence. On MR imaging, the hemangioma (Fig. 4)demonstrates a higher signal intensity on the progressivelymore heavily T2-weighted images (6). Enhancement ofthese lesions following contrast administration is theirtypical feature.

Vascular MalformationsUnlike the hemangiomas, vascular malformations are

true congenital vascular anomalies rather than tumors (5).Their endothelial cell proliferation and turnover character-istics are normal, and they demonstrate a slow, steadygrowth pattern that is commensurate with the growth ofthe child, and further, they also never involute. There canbe capillary, venous, arteriovenous, and lymphatic malfor-mations. Although venous malformations (Fig. 5) mayappear very similar to hemangioma, the identification ofdiscrete areas of homogeneous high signal intensity, whichrepresent venous lakes, or the presence of phleboliths maybe helpful in suggesting the diagnosis of a venous malfor-mation (6, 7). Arteriovenous malformations demonstrate

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Fig. 6. Arteriovenous malformation in a32-year-old man.A. A transverse T2-weighted MR imageshows the intermediate signal intensitymass lesion (arrows) with multiple signalvoids (arrowheads) in the right buccalspace. B. A MR angiography shows the tortuousand dilated facial artery and the internalmaxillary artery.

A B

Fig. 7. Cystic lymphangioma in a 2-year-old boy.A transverse T2-weighted MR image shows multiple cysticlesions with fluid-fluid levels (arrowheads).

Fig. 5. Venous malformation in a 22-year-old woman.A. A transverse T2-weighted MR imageshows a high signal intensity mass lesionoccupying the buccal space and themasticator space. Note the multiplephleboliths (arrows) having low signalintensity.B. The lateral radiograph obtained afterthe percutaneous injection of anethanolamine oleate and iodized oilmixture shows the radiopaque cast fillingthe vascular space of the lesion. Note themultiple laminated phleboliths (arrows).

A B

characteristic serpiginous flow voids on MR imaging (Fig.6). Lymphatic malformations are cystic masses composedof dysplastic endothelium-lined lymphatic channels thatare filled with protein-rich fluid. Lymphatic malformations(Fig. 7) generally appear as cystic and septated lesions withfluid-fluid levels (7).

INFECTION AND INFLAMMAROTY LESIONS

Infections within the buccal space commonly result fromdental infections, stenosis or calculi that are within thesalivary gland ductal systems (2). In many cases, dentalinfections may primarily involve the masticator space andthe infection has secondarily spread to the buccal space.An abscess will appear as a single or multiloculated low-density area with peripheral rim enhancement (Fig. 8).Adjacent muscle enlargement, thickening of the overlyingskin and dirty edematous fat are typically present. Thepresence of these cutaneous and subcutaneous manifesta-tions without a definite low-density collection of is consis-tent with a cellulitis condition.

NEOPLASTIC LESIONS

Minor Salivary Gland TumorMost of the buccal space tumors have a nonspecific

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Fig. 8. Abscess in a 60-year-old man.A transverse enhanced CT scan shows a multiloculated low-density area (thick arrows) with peripheral rim enhancement inthe left buccal space, parotid space and parapharyngeal space.Note the right periapical abscesses confined by the right buccina-tor (thin arrow).

Fig. 9. Pleomorphic adenoma in a 65-year-old woman.A. A transverse T2-weighted MR image shows a round, well-defined mass with bright signal intensity in the right buccal space.B. A transverse T1-weighted MR image shows a round mass with low signal intensity in the right buccal space.C. An enhanced transverse T1-weighted MR image shows homogeneous enhancement of the lesion.

A B C

Fig. 10. Adenoid cystic carcinoma in a75-year-old woman.A. A transverse T2-weighted MR imageshows a small round mass (arrows) withcentral bright signal intensity. Note the ill-defined infiltration of high signal intensityinto the right buccinator muscle(arrowheads).B. An enhanced transverse T1-weightedMR image shows peripheral enhance-ment (arrows) of the mass. Note the ill-defined infiltration into the right buccina-tor muscle (arrowheads) with goodenhancement.

A B

imaging appearance (3). Pleomorphic adenomas are themost common benign glandular tumors and they arecharacterized by the presence of both mesodermal andglandular tissue. They tend to have a rounded appearance,and they demonstrate low signal intensity on T1-weightedimages and high signal intensity on T2-weighted images(Fig. 9). Adenoid cystic carcinoma (Fig. 10) comprises

more than 25% of the malignancies that occur in the minorsalivary glands. Masses with a higher signal intensity on theT2-weighted images correspond to those tumors having alow cellularity and a better prognosis, while those tumorswith a low signal intensity generally have a dense cellular-ity and a poor prognosis (8). Generally speaking, themasses having intermediate to low signal intensity on theT2-weighted images or if they display invasion ofsurrounding tissue planes, then they are more likely to be amalignant lesion (9). However, a small malignant salivarygland tumor (Fig. 11) is likely to have a sharp margin,which mimicks a benign tumor (1).

RhabdomyosarcomaRhabdomyosarcomas are rare malignant mesenchymal

tumors, and 36% of these will involve the head and neck(2). Rhabdomyosarcomas appear as muscle density masseson CT, and their signal intensity on the T2-weighted MRimages is greater than that of muscle. These tumors tend toinfiltrate the surrounding structures and exhibit variousdegrees of enhancement (Fig. 12).

NeurofibromaNeurofibromas involving the buccal space are usually

associated with neurofibromatosis. Neurofibromas show

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Fig. 12. Rhabdomyosarcoma in a 15-year-old girl.A. A transverse T2-weighted MR imageshows a round, well-demarcated mass ofhigh signal intensity in the right buccalspace.B. An enhanced coronal T1-weightedMR image shows the heterogeneousenhancement of the lesion.

A B

Fig. 13. Plexiform neurofibroma in a 20-year-old man.A transverse T2-weighted MR image shows ill-defined high signalintensity mass involving the buccal space, masticator space,parapharyngeal space, parotid space and auricle.

Fig. 11. Carcinoma ex pleomorphicadenoma in a 70-year-old man.A. A transverse T2-weighted MR imageshows a round mass of bright signalintensity and small, low signal intensityspots in the left buccal space (arrow).B. An enhanced transverse T1-weightedMR image shows the mildly enhancingfoci (arrow).

A B

high signal intensity on the T2-weighted images and theyexhibit strong enhancement after the administration ofcontrast medium (2). The signal of a solitary neurofibromaon the T2-weighted images can be either homogeneouslyhyperintense or it can show a characteristic target sign witha central hypointense region. The plexiform neurofibromais seen as an ill-defined, infiltrative lesion that usuallyinvolves multiple contiguous neck spaces (Fig. 13).

LymphomaAccording to the WHO classification, lymphoid

malignancies are largely divided into T-cell neoplasms, B-cell neoplasms, and Hodgkin disease. The imaging charac-teristics of B-cell lymphomas (Fig. 14) are good demarca-tion, homogeneity, compression, and molding rather thaninvasion (10). On the contrary, the imaging features ofperipheral T-cell lymphomas (Fig. 15) are nonspecific andinfiltrative, and the radiologic differential diagnoses caninclude bacterial, fungal or parasitic infection, andcutaneous metastases from malignant melanoma or breast

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Fig. 15. Peripheral T-cell lymphoma in a57-year-old woman.A. A transverse CT scan shows the ill-defined infiltrative lesions in both thebuccal space and the subcutaneouslayer on the right cheek. Note the overly-ing skin thickening (arrowhead).B. A transverse T1-weighted MR imageshows the ill-defined infiltrative lesions inthe same area.

A B

Fig. 14. Non-Hodgkin lymphoma of the diffuse small cell type in a49-year-old man. A transverse CT scan shows a homogeneoussolid mass in the left buccal space. Note the molding pattern ofthe mass and the lack of mass effect on the left masseter muscle(arrowheads).

Fig. 16. Surgically confirmed metastatic lymphadenopathy in a71-year-old man. A transverse T2-weighted MR image shows awell-circumscribed mass (arrow) with central high signal intensity.The patient underwent left partial mandibulectomy due tosquamous cell carcinoma of the gingiva.

Fig. 17. Foreign body granuloma in a 49-year-old woman with ahistory of paraffin injection into both cheeks 20 years ago. Atransverse enhanced CT scan shows the ill-defined infiltration(arrows) and several small calcifications around the bilateralbuccal spaces.

cancer (11).

Metastatic Lymph NodeBuccal space lymph node matestasis (Fig. 16) is typically

associated with squamous cell carcinoma of the face. Itappears as a well-circumscribed mass with rim enhance-ment and central low attenuation on the CT scan or as highsignal intensity on the T2-weighted images (1).

MISCELLANEOUS LESIONS

Foreign Body GranulomaInjection of foreign materials such as paraffin into the

breast or face for cosmetic reasons is an uncommon andold method used in the Asian countries. On mammogram,paraffinoma of the breast manifests as multinodularradiopaque opacities with calcifications or as spiculatedmasses that mimick breast cancer (12). On CT scan of theface, paraffinoma appears as an ill-defined infiltration inthe buccal fat pad and the subcutaneous fat with multiplepunctate calcifications (Fig. 17). When calcifications associ-ated with soft tissue infiltration are incidentally noticed onCT, particularly bilaterally, the diagnosis of foreign bodygranulomas secondary to cosmetic cheek augmentation ishighly possible and an appropriate review of the medicalhistory is highly recommended.

Kimura DiseaseKimura disease is a rare entity that occurs primarily in

Asian subjects, and this disease is characterized histopatho-logically by a lymph-folliculoid granuloma with eosinophilinfiltration. The common clinical features are an asympto-matic mass and local lymphadenopathy, particularly in theparotid and submandibular regions. The lesions of Kimuradisease (Fig. 18) show a variety of high signal intensities onthe T2-weighted images according to the degrees of fibrosisand vascular proliferation, and they show strong enhance-

ment on the enhanced T1-weighted images (13).

CONCLUSION

There are various pathologies that can occur in thebuccal space. Although the purpose for imaging the buccalspace lesions is primarily to determine the origin andextent of the lesions, knowledge of the expected CT andMR imaging findings can be helpful for the radiologist todiagnose the specific etiology of the lesions.

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Fig. 18. Kimura disease in a 14-year-oldboy.A. A transverse T2-weighted MR imageshows an infiltrative mass-like lesion(arrow) having high signal intensity in theleft buccal space.B. A transverse enhanced T1-weightedMR image shows moderate enhance-ment of the lesion.

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