Head & neck imaging
Case TypeClinical Cases
Authors
Ana Germano, Carolina Durão, João Rito, Gustavo Rocha, Maria Gabriela Gasparinho, Filipe Freire
Patient54 years, female
A 54-year-old woman presented with a 2-week history of throat foreign body sensation, and dyspnoea. On physical examination, her breathing was noisy. She denied pain and fever. Nasopharyngoscopy detected an airway lumen stenosis caused by a hypopharynx submucosal mass. Past history and lab tests were unremarkable except for thyroid nodules.
Neck CT before and after intravenous contrast reveals a lesion in the infrahyoid retropharyngeal space, extending from the level of the free edge of the epiglottis, above, to the glottis level below. It is well-defined, oval, hypodense, without calcifications, with moderate enhancement after intravenous contrast. A thin peripheral rim of fat can be found separating the lesion from the posterior pharyngeal wall anteriorly, and from the prevertebral muscles posteriorly. The cervical oesophagus originates below the lesion and has no relation with it.
Neck MRI (T1 before and after gadolinium, fat-suppressed T1, and T2 sequences in the axial, sagittal and coronal planes) was performed. The oval retropharyngeal lesion is isointense to the muscles on T1, with vivid enhancement after gadolinium. It is heterogeneously bright on T2, where we can also identify multiple small, ring-like structures with peripheral hyperintensity.
A transoral approach was used to surgically remove the lesion.
Background
The retropharyngeal space (RPS) extends from the skull base to the mediastinum (between the T2 and T6 vertebral bodies). It is bounded anteriorly by the buccopharyngeal fascia, posteriorly by the alar fascia, and divided in supra-hyoid and infra-hyoid compartments. The first contains fat and lymph nodes, the second contains only fat [1,2,3]. The most frequent lesions in this space are infectious (abscesses, cellulitis), metastatic lymph nodes, or direct invasion from pharyngeal mucosal space carcinoma. Occasionally tortuous carotid arteries, or bulging from vertebral osteophytes can be seen. There are only sporadic reports of primary tumours of the RPS (lipomas, neuroblastomas, pleomorphic adenomas, schwannomas). Schwannomas are exceedingly rare in this space and are thought to originate from small branches of the pharyngeal nerve plexus [1,4,5].
Clinical Perspective
Schwannomas are benign, slow-growing lesions, symptomatic when they grow. Reported symptoms at diagnosis include snoring, foreign body sensation and progressive dysphagia [1-4,6,7]. Nasopharyngoscopy usually shows a posterior submucosal bulging with intact mucosa. Sectional imaging is needed to further characterize the exact location, boundaries, relation with adjacent structures and intrinsic characteristics of these lesions. Assessment of the relation with the carotid arteries, vertebrae, and possible invasion of neighbouring structures is crucial to plan the surgical approach [1-7].
Imaging Perspective
CT and MRI are the imaging modalities of choice. Key findings include an oval or fusiform-shaped lesion, with well-defined margins, hypodense on CT, iso or hypointense on T1-weighted and hyperintense on T2-weighted MRI sequences, that enhances after contrast media administration. A thin rim of fat surrounding the lesion is often found (split fat sign), as well as several little ring-like forms with outlying high signal on T2 (fascicular sign [8].
The final diagnosis is made by histopathology.
Outcome
Complete surgical resection is the therapy of choice. Surgical approach is chosen based on the size and location of the lesion. Prognosis is excellent with a complete recovery usually achieved in a short period of time.
Take-Home Message
Written informed patient consent for publication has been obtained
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[2] Ngu CYV, Gan CC, Tang IP (2017) Transoral excision of retropharyngeal schwannoma: Case report Acta Oto-Laryngologica Case Reports 2 (1) 64-67 (DOI: 10.1080/23772484.2017.1303773)
[3] Hsieh C-Y, Hsiao J-K, Wang C-P (2006) retropharyngeal schwannoma excised through a transoral approach: a case report J Med Sci 22 (9):465-469 (PMID 17000449)
[4] Carpintero YE, Artal AFA, Moreno MP (2020) Retropharyngeal Schwannoma. An Uncommon Location Acta Otorrinolaringol Esp. 71(3):193-194 (PMID 31113533)
[5] Schmäl F, Stoll W (2002) Differential Diagnosis and managment of retropharyngeal space occupying lesions HNO 50(5):418-423 (PMID 12089808)
[6] Sakhrekar R, Peshattiwar V, Jadhav R et al (2020) Extremely rare case of retropharyngeal space benign plexiform schwannoma - Excised through SmithRobinson Approach Surgical Neurology International 11(182):1-4 (DOI:10.25259/SNI_317_2020)
[7] Kumagai M, Endo S, Shiba K et al (2006) Schwannoma of the Retropharyngeal space Tohoku J. Exp. Med. 210:161-164 (PMID 17023770)
[8] Murphey MD, Smith WS, Smith SE et al (1999) Imaging of Musculoskeletal Neurogenic Tumors: Radiologic-Pathologic Correlation RadioGraphics 19:1253–1280 (PMID 10489179)
URL: | https://www.eurorad.org/case/17778 |
DOI: | 10.35100/eurorad/case.17778 |
ISSN: | 1563-4086 |
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