Cervical thymus

The cervical thymus refers to the ectopic location of thymus at the cervical level above the brachiocephalic vein.

A cervical thymus usually presents before adolescence as a painless unilateral midline or lateral neck mass.

Around the 4th to 5th week of gestation, development of the thymus begins from the 3rd branchial pouch. Towards the end of the 6th week, the thymus traverses caudomedially into the inferoanterior mediastinum before fusing in the midline.

Ectopic tissue may occur anywhere along this path secondary to failure of or incomplete descent, implantation or persistence of remnant tissue or failure of involution; resulting in a cervically positioned thymus above the brachiocephalic vein.

Sonographic characteristics of the parenchyma are the same as normally positioned tissue:

  • multiple linear hyperechoic septa
  • discrete homogeneously distributed hyperechoic foci giving a "speckled" appearance

Contiguity with the normally positioned thymus may be seen with the thymopharyngeal duct.

No intervention is required as normal involution will usually occur with age. Like normal thymic tissue, residual focal thymic tissue may persist throughout life as a normal variant.

The clinical differentials for a cervical thymus can include:

  • adenopathy
  • branchial cleft anomaly
  • hemangioma
  • lipoma
  • teratoma

However, if the characteristic normal thymic echo pattern is demonstrated, other differential diagnoses are easily excluded.

Share article

Article information

rID: 62081
Synonyms or Alternate Spellings:

Support Radiopaedia and see fewer ads

Cases and figures

  • Case 1
    Drag here to reorder.
  • Case 2
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.