Veronika Huf (Klinikum Augsburg/Abteilung Kinderradiologie/Augsburg/Deutschland), Kurt Vollert (Klinikum Augsburg/Abteilung Kinderradiologie/Augsburg/Deutschland), Tobias Schuster (Klinikum Augsburg/Abteilung Kinderchirurgie/Augsburg/Deutschland)  

Viewable for logged on visitors (Log on)  

6 Months  

Male  

Neck-Other and unknown  

congenital  

Swelling in the right mandibular angle, movable, indolent,stable size for over 2 months.  

Normal development: Cells of the ventral bud of the 3rd pharyngeal pouch detach and migrate in the 8th gestational week caudally and medially towards the thyroid. They migrate further retrosternally into the superior mediastinum.

Development of ectopic thymus tissue:
1. Cells detach along the descensus path and proliferate -> development of accessory thymus tissue.
2. The entire gland or a lobe does not descend and stays at loco -> ectopic thymus tissue.  

<- view Ultrasound 1

Ultrasound 1: Ultrasound of the tumor in the right mandibular angle which is hypoechoic and extending deeply into the soft tissue.




<- view Ultrasound 2

Ultrasound 2: The tumor extends between the neck vessels (internal jugular vein and common carotid artery) without signs of invasion.



<- view Ultrasound 3

Ultrasound 3: Good vascularization on Doppler ultrasound



<- view MRI 1

MRI 1: T1w noncontrast axial; the tumor is nearly isointense to muscle. The hyperintense areas represent predominantly protein-rich cysts or fat.





<- view MRI 2

MRI 2: T2w SPIR axial; The known tumor is hyperintense to muscle.





<- view OP-Situs 1

OP-Situs 1: intraoperative findings of the tumor in the right mandibular angle




<- view Histology 1

Histology 1: Hassall's bodies in the central portions of the specimen.




<- view Histology 2

Histology 2: Hassall's bodies in the central portions of the specimen.



 

Surgery / Histo  

Hemangioma, Metastasis, Teratoma, Sarcoma, Thyroid tumor  

Ectopic thymus tissue is more frequently prevalent than traditionally suggested. With improved diagnostic modalities (e.g. ultrasound) the diagnosis is more frequently made. 61 % of 18 children who were examined in the neck area had ectopic thymus tissue in the neck according to the literature (see reference). Since we were sensitized for this diagnosis, we diagnosed at least 4 children with ectopic thymus tissue as an incidental finding.
Rarely, a malignant transformation of ectopic thymus tissue has been described in the literature. Thus, in our opinion is a conservative/awaiting position with follow up imaging studies justified.  

N/A  

N/A  

1. Medline:
Chu WXW, Metreweli C
Ectopic thymic tissue in the paediatric age group
Acta Radiologica 2002;43:144-6  

ectopic thymus,neck swelling,accessory thymus, child, childhood, pediatric radiology  

Veronika Huf, Kurt Vollert, Tobias Schuster. Ectopic Thymus. PedRad [serial online] vol 7, no. 7.
URL: www.PedRad.info/?search=20070724201543