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CASE REPORT
Year : 2012  |  Volume : 1  |  Issue : 4  |  Page : 265-267

Thymic cyst in the differential diagnosis of pediatric lateral cervical masses


Department of Pediatric Surgery, Vani Vilas Hospital, Bangalore Medical College and Research Institute, Bangalore, India

Date of Web Publication27-Dec-2012

Correspondence Address:
Raghu S Ramareddy
Department of Pediatric Surgery, Vanivilas Hospital Bangalore Medical College and Research Institute, Bangalore
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2277-8632.105111

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  Abstract 

Thymic cyst is a very rare differential diagnosis of pediatric neck swellings and often misdiagnosed as either branchial cleft cyst or cystic hygromas. An eleven year old boy presented a painless left lateral cervical swelling with initial diagnosis of branchial cyst. He underwent complete excision of the lesion and histological examination confirmed a thymic cyst. The embryological development, clinical presentation, differential diagnosis, pathology and management of ectopic thymic lesions are discussed together with a brief review of the literature.

Keywords: Cervical ectopic thymus, children, neck masses


How to cite this article:
Ramareddy RS, Alladi A. Thymic cyst in the differential diagnosis of pediatric lateral cervical masses. J NTR Univ Health Sci 2012;1:265-7

How to cite this URL:
Ramareddy RS, Alladi A. Thymic cyst in the differential diagnosis of pediatric lateral cervical masses. J NTR Univ Health Sci [serial online] 2012 [cited 2020 Apr 6];1:265-7. Available from: http://www.jdrntruhs.org/text.asp?2012/1/4/265/105111


  Introduction Top


Cervical ectopic thymic cyst is rarely reported in medical literature. It may be found at any level of the normal pathway of thymic descent, from the angle of the mandible to the superior mediastinum. Seldom considered in the differential diagnosis of neck masses, its presence is often revealed by pathologic examination of an excised specimen. [1],[2],[3],[4],[5]


  Case Report Top


An eleven year old boy presented with progressive left lateral cervical swelling since 1 year. Local examination revealed a globular swelling with variable consistency, mobile and partly deep to sternocleidomastoid muscle (SCM). Ultrasound showed heterogeneous lesion with internal echoes, postero lateral to the left thyroid lobe. Clinically, a diagnosis of left branchial cyst was made and swelling was approached through cervical incision and excised in toto after transfixing its proximal fibrinous extension to pharyngeal wall. The cyst was intimately related to the carotid sheath [Figure 1].
Figure 1: Operative picture showing Multilocular thymic cyst is dissected from carotid vessel (right arrow) and sternocleidomastoid muscle (up arrow)

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Gross examination revealed multi-loculated cyst filled with thick, yellow, inspissated material in the upper part and nodule with pultaceous material in lower part [Figure 2]. Microscopic examination of cyst wall had features of lymphoid tissue, Hassall's corpuscles, cuboidal epithelium, cholesterol cleft and foci of foreign body giant cells suggestive of thymic tissue [Figure 3]. Post-operative and follow-up after 2 years was uneventful.
Figure 2: Multilocular Thymic Cyst (hollow arrow) with serous, yellow fluid (bold arrow)

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Figure 3: Microscopy 10x2 H and E stain reveal lymphoid tissue (arrow down) Hassal's corpuscles (right arrow) suggestive of thymic tissues

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  Discussion Top


Cervical ectopic thymus is an uncommon neck lump and usually described as sporadic case reports, slightly more than 150 cases of congenital ectopic thymus have been reported in world literature. [3]

The thymus gland develops mainly from the ventral part of paired 3 rd pharyngeal pouch and occasionally from the 4th pouch in the neck, descends down as thymopharyngeal tracts along the course of carotid sheath to the final position in the superior mediastinum during 6 th to 9 th week of gestation. It forms the bilobed thymus gland by third month. [3],[4] It has a physiological role in development of immune mechanism in infants and children. [3]

The primary event in ectopic thymic cysts is an arrest of migration of thymic tissue or sequestration and persistence of thymic vestiges along the line of descent of the thymopharyngeal tract, followed by degeneration of Hassall's corpuscles and/or epithelial component of the aberrant thymic tissue. [1],[2],[6],[7],[8]

Cervical thymic cysts are very uncommon lesion with slightly male preponderance, [6] majority being asymptomatic. Rarely they may present with obstructive aero-digestive system, [2],[9] soft, unilocular or, more frequently multilocular mass filled with clear, serous fluid or brown thicker hemorrhagic fluid. [3] It predominantly affects left side of the neck, [2],[9] young children and adolescents, and have mediastinal extension in 50%. [1],[7] They are closely related to SCM and carotid sheath contents.

The usual etiologies of benign lateral neck masses in children are cystic hygromas, branchial cleft cyst, lymphangioma, lymph node, haemangiomas, hemangiolymphangiomas, cervical teratomas, thyroid and parathyroid cyst. [4],[5],[6] Age, gender, size of the mass, location, and features of its manifestation helps in the differential diagnosis. [4],[10]

Cervical thymic cyst shares a similar anatomical location and lymphoid tissue with branchial cysts but appear earlier. [3] The lymphoid tissue in the wall of a thymic cyst is predominantly of thymic origin and usually includes Hassal's corpuscles where-as lymphoid tissue associated with branchial cysts often exhibits germinal centers. The cystic spaces may be lined by cuboidal, columnar, or stratified squamous epithelium. The epithelium may be focally replaced by fibrous or granulation tissues with cholesterol clefts and giant cell reaction. Cystic hygromas typically appears commonly as a multilocular cystic mass with septations of variable thickness below 2 years. It ' s usually centered in posterior triangle or submandibular space and spreads along vital structure. [3] Complete excision with single cervical incision is the ideal treatment of choice for ectopic thymus after confirming the presence of normal thymus. [1],[3],[5],[6]


  Conclusion Top


Cervical ectopic thymus cysts are uncommon but should be included in the differential diagnosis of neck masses, especially in the young. Such anomalies are rarely diagnosed pre-operatively and pathologist must keep this entity in mind when evaluating resection specimens from children with undiagnosed neck lesion. Its behavior is uniformly benign and complete excision is curative.

 
  References Top

1.Nguyen Q, deTar M, Wells W, Crockett D. Cervical thymic cyst: Case reports and review of the literature. Laryngoscope 1996;106:247-52.  Back to cited text no. 1
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2.Millman B, Pransky S, Castillo J 3rd, Zipfel TE, Wood WE. Cervical thymic anomalies. Int J Pediatr Otorhinolaryngol 1999;47:29-39.  Back to cited text no. 2
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3.Cigliano B, Baltogiannis N, De Marco M, Faviou E, Antoniou D, De Luca U, et al. Cervical thymic cysts. Pediatr Surg Int 2007;23:1219-25.  Back to cited text no. 3
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4.Saggese D, Ceroni Compadretti G, Cartaroni C. Cervical ectopic thymus: A case report and review of the literature. Int J Pediatr Otorhinolaryngol 2002;66:77-80.  Back to cited text no. 4
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5.Baek CH, Ryu JS, Yun JB, Chu KC. Aberrant cervical thymus: A case report and review of literature. Int J Pediatr Otorhinolaryngol 1997;41:215-22.  Back to cited text no. 5
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6.Kacker A, April M, Markentel CB, Breuer F. Ectopic thymus presenting as a solid submandibular neck mass in an infant: Case report and review of literature. Int J Pediatr Otorhinolaryngol 1999;49:241-5.  Back to cited text no. 6
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7.Barat M, Sciubba JJ, Abramson AL. Cervical thymic cyst: Case report and review of literature. Laryngoscope 1985;95:89-91.  Back to cited text no. 7
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8.Speer FD. Thymic cyst: Report of a thymus presenting cysts of three types. N Y Med Coll Flower Hosp Bull 1938;1:142-50.  Back to cited text no. 8
    
9.Guba AM Jr, Adam AE, Jaques DA, Chambers RG. Cervical presentation of thymic cysts. Am J Surg 1978;136:430-6.  Back to cited text no. 9
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10.Felgentreff K, Schupp W, Otten JE, Rückauer KD, Uhl M, Jüttner E et al. Inspiratory stridor and dysphagia in two newborn infants caused by ectopic thymus tissue. Eur J Pediatr 2009;168:1141-5.  Back to cited text no. 10
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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   Abstract
  Introduction
  Case Report
  Discussion
  Conclusion
   References
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