Review Article Imaging diagnosis of nasopharyngeal tumors IMAGING DIAGNOSIS OF NASOPHARYNGEAL TUMORS* Ilka Yamashiro1, Ricardo Pires de Souza2 Abstract The nasopharynx is located in the upper aerodigestive tract. Its roof is formed by the basisphenoid, basiocciput and the anterior aspect of the first two cervical vertebrae, in front of the clivus. The lateral walls are formed by the margins of the superior constrictor muscle and the pharyngobasilar fascia, pharyngeal recess, torus tubarius and pharyngeal opening of auditory tube. The inferior margin of the nasopharynx is a horizontal plane passing through the hard palate and palatopharyngeal muscle. Anteriorly, it is in direct continuity with the nasal cavity through the posterior choanae. It is approximately 2.0 cm in anteroposterior diameter and about 4.0 cm in craniocaudal extent. Squamous cell carcinoma accounts for about 70% to 98% of nasopha- ryngeal malignant lesions found in adults. This tumor presents a high incidence in Asians, most frequently in men, and is the third most frequent cancer in women. The clinical presentation of this disease depends on the size and site of the lesion, with small-sized lesions being asymptomatic. Computed tomography and magnetic resonance imaging play essential and complementary roles in the staging and treatment of pa- tients with nasopharyngeal cancer. Keywords: Computed tomography; Nasopharynx; Tumor; Carcinoma. Resumo Diagnóstico por imagem dos tumores da nasofaringe. A nasofaringe é a parte mais superior das vias aéreas superiores. Seu limite superior é a base do osso esfe- nóide e occipital, situa-se anteriormente às duas primeiras vértebras cervicais e à frente do clivo. Seus limi- tes laterais são formados pelas margens do músculo constritor superior da faringe e pela fáscia faringobasi- lar, recessos faríngeos, toro tubário e tuba auditiva. O limite inferior é um plano horizontal que passa pelo palato duro e pelo músculo palatofaríngeo. Anteriormente, comunica-se com a cavidade nasal via coana posterior. Mede cerca de 2,0 cm de diâmetro ântero-posterior e cerca de 4,0 cm de extensão crânio-caudal. O carcinoma de células escamosas compreende aproximadamente 70% a 98% de todas as neoplasias ma- lignas da nasofaringe em adultos. Este tipo de tumor apresenta alta incidência na população asiática, sendo mais comum entre os homens e o terceiro mais comum entre as mulheres. A manifestação clínica do carci- noma da nasofaringe depende do tamanho da lesão e da sua localização, sendo que as lesões de pequenas dimensões são geralmente assintomáticas. A tomografia computadorizada e a ressonância magnética de- sempenham papel essencial e complementar no estadiamento e no tratamento dos pacientes portadores de câncer da nasofaringe. Unitermos: Tomografia computadorizada; Nasofaringe; Tumor; Carcinoma. ANATOMICAL SUBSTRATE riorly, and the carotid spaces laterally. The membrane, and does not represent a signifi- inferior margin of the nasopharynx is a cant barrier to neoplastic or infectious dis- The nasopharynx is the upper part of the horizontal plane passing through the hard semination from the nasopharynx into ad- superior aerial tract, and corresponds to the palate and palatopharyngeal muscle. Later- jacent spaces(3,4). Laterally, it covers the superior end of the pharynx. It contains the ally, it is limited by the margins of the su- pharynx, superiorly inserting into the skull lateral pharyngeal recess, the torus tubarius perior constrictor muscle, the pharyngo- base through the pharyngeal tubercle, with and the pharyngeal tonsil. basilar fascia and by the parapharyngeal the superior constrictor muscle, pharyngo- The nasopharynx is situated at the cen- space(1). Its wall is formed by three layers: basilar fascia, and in the posterior margin ter of the skull base. The anatomical rela- a mucous lining, a muscular layer and a of the medial pterygoid plate. tions of the nasopharynx include the clivus fibrous membrane denominated pharyngo- The structural protrusion and the tissues posteriorly, the posterior nasal cavity ante- basilar fascia. of the pharyngeal wall give shape to the It is approximately 2.0 cm in anteropos- mucosal lining of the nasopharynx, deter- terior diameter and about 4.0 cm in cranio- mining anatomical landmarks utilized in * Study developed at Service of Diagnostic Imaging – Hospi- caudal extent(2). clinical evaluations and interpretation of tal Heliópolis Department of Radiology, São Paulo, SP, Brazil. 1. MD, Trainee at Service of Diagnostic Imaging – Hospital The middle layer of the deep cervical computed tomography (CT) and magnetic Heliópolis Department of Radiology, Master Degree Student in fascia or buccopharyngeal fascia is charac- resonance imaging (MRI) cross-sectional Health Sciences at Hospital Heliópolis. 2. Coordinator for Medical Residence in Diagnostic Imaging terized by a condensation of cellular tissue slices, as follows: a) torus tubarius – is the at Service of Radiology of Hospital Heliópolis. surrounding the lateral and posterior por- most prominent of these structures, corre- Mailing Address: Dra. Ilka Yamashiro. Rua Afonso Celso, 1637, ap. 33, Chácara Inglesa. São Paulo, SP, 04119-062 – Brazil. tions of the nasopharynx, providing it with sponding to a projection of the cartilagi- E-mail: [email protected] a fascial limit as an interface with the nous portion of the auditory tube. It is vi- Received October 28, 2004. Accepted after revision March 17, 2005. neighboring structures. It is a tender, subtle sualized as a protrusion projecting into the Radiol Bras 2007;40(1):45–52 45 Yamashiro Y, Souza RP lateral wall of the nasopharyngeal cavity, (palatopharyngeal, stylopharyngeal and Abundant lymphoid tissue in the chorium both on CT and MRI; b) pharyngeal ostium salpingopharyngeal), palatoglossus, tensor forms a part of the pharyngeal lymphatic of auditory tube – localized antero-inferi- palati and levator palati, and the palatopha- ring, a probable site for development of orly to the torus tubarius(5). On CT and MRI ryngeal muscle; non-Hodgkin lymphoma, the most frequent axial slices, it is observed as a small recess b) a fibrous structure or pharyngobasilar malignant nasopharyngeal neoplasm(2,10). in the nasopharynx lateral wall; c) The sal- fascia situated between the muscular tunica Smaller salivary glands are present in the pingopharyngeal fold, a mucosal protru- and mucosa, extending uninterruptedly sub-mucosa surrounding the auditory sion determined by the submucosal tract of from the upper to the lower end of the phar- tubes, and might be a focus for benign or the salpingopharyngeal muscle forming the ynx, absent in the anterior portion, except malignant nasopharyngeal lesions. anterior limit of the lateral pharyngeal re- in the attachment to the larynx where it is The knowledge of anatomical variations cess; d) the lateral pharyngeal recess, pos- circular(1). Cranially, where its external sur- of this region is important to avoid confu- teriorly located, and extending superiorly face is not covered by a muscular layer (be- sion between normal alterations and dis- to the salpingopharyngeal fold and torus tween the skull base and the inferolateral ease. tubarius (Figures 1 and 2). It is the most fre- portion of the auditory tube cartilage), there Asymmetry of mucosal landmarks, es- quent site of origin for nasopharyngeal is a lateral space denominated Morgagni pecially the pharyngeal recess asymmetry, squamous cell carcinoma(6). It originates in sinus. It is through this space that the au- is a frequent variation. A decrease in depth a subtle mucosal herniation through the ditory tube and the levator palati penetrate of the pharyngeal recess, or even its col- Morgagni sinus, a region on the pharyngeal into the nasopharynx internal portion. The lapse as a normal finding should be differ- wall where muscular fibers are absent. The Morgagni sinus, because of its anatomical entiated from disease. The analysis of ad- degree of distensibility is highly variable. characteristic, is an important route for the jacent, deep planes showing their integrity It tends towards being symmetrical, al- carcinoma dissemination from the na- or symmetry suggests normality (Figure 3). though subtle asymmetries are not uncom- sopharynx towards adjacent spaces like the Also, the acquisition of CT images during mon to be found at MRI and CT(7). In parapharyngeal space; modified Valsalva maneuver or wide open- youngsters, it presents with less amplitude c) a mucosal membrane or internal tu- ing of the mouth might be useful. The because of the presence of retropharyngeal nica lining internally the pharyngobasilar modified Valsalva maneuver results in a lymphoid tissue(8). fascia, continuing with the mucosal lining maximum distention of the auditory tube The nasopharynx is formed by: of the nasal cavity and oropharynx. It is ostium and pharyngeal recess. The wide a) A muscular layer formed by the up- formed by ciliated pseudo-stratified epithe- opening of the mouth distends the pharyn- per, middle and lower pharyngeal constric- lium and chorium with a plenty of mucipa- geal recess and increases the auditory tube tor muscles, pharyngeal levator muscles rous glands and lymphoid follicles(9). ostium depth(7). Figure 1. Scheme of axial view, in slightly different planes: SM, maxillary sinus; TM, middle Figure 2. Contrast-enhanced CT axial view: normal anatomy. SM, turbinate; P, posterior choana; N, nasopharynx; LM, medial pterygoid lamina; F, pterygoid maxillary sinus; TM, middle turbinate; P, posterior choana; N, fossa;
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