cervical thymic cyst · 2018. 11. 20. · 4. cervical thymic cyst: a rare differential diagnosis in...
TRANSCRIPT
Reporter: R 陳柏安
Supervisor: Chief 賴炳宏
Date: 2017/12/16
Case Discussion
• Gender: female
• Birth History: 36+5 wks, 2032gm, C/S
• Chief Complain: Sudden found a left neck mass 2 wks after birth. 4x2 cm
Patient Profile
• Cystic lesion within fluid-fluid level
US
• z
MRI
• z
MRI
MRI
• Enhanced smooth thin-walled, cystic unilocular mass with fluid-fluid level
• Hypointensity on T1WI • Mixed hyperintensity on T2WI • Extension to supraclavicular fossa and left
retrophayngeal area • About 4.7*3.7*3.1 cm in size • Lateral-posterior displacement of left carotid
artery and jugular vein • Anterior displacement of left thyroid gland
MRI
What is your impression or differential diagnosis?
• A well-defined large lesion over the left neck without local invasion, with cystic straw-colored clear liquid content.
Operative Findings
• Compatible with cervical thymic cyst
• Contains thymic tissue with Hassall corpuscles in the wall
Pathologic Diagnosis
Squamous cell
Thyroid
Parathyroid Hemorrhage
Hassall's corpuscles
Discussion: Cervical Thymic Cyst
• Cystic remnant of thymopharyngeal duct, derivative of 3rd pharyngeal pouch
Etiology
• Failure of obliteration of thymopharyngeal duct
• Thymopharyngeal duct arises from pyriform sinus, descends into mediastinum
• Persistent sequestered remnants may occur from mandible to thoracic inlet
Etiology
• Peak: 2-15 y/o
• Slight male predilection
• represent less than 1% of cystic cervical masses
Epidemiology
• Often asymptomatic
• Gradually enlarging, soft, compressible mid- to lower cervical neck mass
• When large, may cause dysphagia, respiratory distress, or vocal cord paralysis
Clinical presentation
• Unilocular cystic mass
• extending inferiorly within the neck
• paralleling the SCM or as a dumbbell-shaped left cervicothoracic cystic mass
• Almost always found in left side of neck
• adjacent to the carotid sheath any where from the hyoid bone to the anterior mediastinum
• May splay carotid artery and jugular vein
Image Features
• Thin-walled anechoic or hypoechoic lateral neck mass
• Rarely has solid nodules
in wall
US of CTC
• Dumbbell-shaped left cervicothoracic cystic mass highly suggestive of either thymic cyst or lymphatic malformation
• If unilocular lesion with discrete margins, may be thymic cyst or unilocular lymphatic malformation
Image Features
Cystic masses of neck: A pictorial review, Mittal, et al., Indian Journal of Radiology and Imaging, 2012 Nov
• CT: Nonenhancing low-attenuation neck cyst
– Solid components rare (aberrant thymic tissue, lymphoid aggregates, or parathyroid tissue)
Image Features
Cervical Thymic Cyst: A Rare Differential Diagnosis in Lateral Neck Swelling, Hindawi Publishing Corporation Case Reports in Otolaryngology, Volume 2013
• T1: homogeneous hypointense, still could be variable
– Solid: iso SI
• T2: homogeneous high SI
• T1+C: wall and solid nodules may slightly enhanced
MRI of CTC
MRI of CTC
• 2nd BCC: when infrahyoid, anterior to carotid space
• 4th BCC: most common cyst anterior to left thyroid lobe
• Lymphatic malformation: fluid-fluid level common
• Abscess
• Thyroid cyst: intrathyroid
• Extremely rare: cervical bronchogenic cyst
Common DDx
• CTCs: close to the carotid sheath, between the internal jugular vein and the carotid vessels
• BCCs: superficial and lateral to both the internal jugular vein and carotid artery
• Lymphangiomas: generally restricted to the posterior triangle of the neck
Common DDx
Thymopharyngeal Duct Cyst An Unusual Variant of Cervical Thymic Anomalies, jamaotolaryngology, 2001 Nov.
• lobulated lymphoid tissue containing Hassall’s corpuscles
Pathological Diagnosis
• Excellent prognosis if completely resected
• Recurrence common if incompletely resected
Prognosis
• Often asymptomatic
• Unilocular cystic mass
• Paralleling the SCM
• Most left side
• Dumbbell-shaped
• Could accompanied with bleeding
• DDx: 2nd BCC, Lymphangiomas, and cervical bronchogenic cyst (rare)
Summary
1. Diagnostic Imaging Head and Neck 2E 2. Cystic masses of neck: A pictorial review, Indian J Radiol Imaging. 2012 Oct;22(4):334-43. 3. Diagnosis and Management of Cervical Thymic Cysts in Children, Cureus. 2017 Jan 11;9(1):e973. 4. Cervical thymic cyst: a rare differential diagnosis in lateral neck swelling, Case Rep
Otolaryngol. 2013;2013:350502. 5. Goff CJ et al: Current management of congenital branchial cleft cysts, sinuses, and fistulae. Curr
Opin Otolaryngol Head Neck Surg. 20(6):533-9, 2012 6. Pahlavan S et al: Microbiology of third and fourth branchial pouch cysts. Laryngoscope.
120(3):458-62, 2010 7. Thomas B et al: Revisiting imaging features and the embryologic basis of third and fourth
branchial anomalies. AJNR Am J Neuroradiol. 31(4):755-60, 2010 8. Sturm-O'Brien AK et al: Cervical thymic anomalies--the Texas Children's Hospital experience.
Laryngoscope. 119(10):1988-93, 2009 9. Statham MM et al: Cervical thymic remnants in children. Int J Pediatr Otorhinolaryngol.
72(12):1807-13, 2008 10. Mehrzad H et al: A combined third and fourth branchial arch anomaly: clinical and embryological
implications. Eur Arch Otorhinolaryngol. 264(8):913-6, 2007 11. Charous DD et al: A third branchial pouch cyst presenting as a lateral neck mass in an adult. Ear
Nose Throat J. 85(11):754-7, 2006 12. Koch BL: Cystic malformations of the neck in children. Pediatr Radiol. 35(5):463-77, 2005
Reference
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