Aberrant thymus — MR assessment

Abstract

Aberrant thymic tissue, particularly when it is located posteriorly, can present a diagnostic dilemma. Once a mediastinal "lesion" is defined on the plain film, MR is the most efficient and best diagnostic test for defining the nature of the mass and showing its relationship to other mediastinal structures. Two cases of aberrant thymic tissue, one on the right side and one on the left, are presented to elucidate the unique role of MRI.

Clinical management of cervical ectopic thymus in children

“…On MRI, the appearance of CET is homogenous, isointense, or slightly hyperintense compared with the muscle on the T1-weighted images and is slightly less intense or isointense compared with the fat on T2-weighted images. Slovis et al [24] believed that MRI is the most efficient and best diagnostic test for defining the nature of the mass and showing its relationship to other mediastinal structures.…”

Accessory thymus in posterior mediastinum

“…[8] It can be connected to the anterior normal thymus or could be completely free from it, as in our case. If it is communicating with the normal thymus anteriorly, the diagnosis can be established on table, but more often the diagnosis is established post-operatively on histopathology as in our case, with similar experiences from other authors who had excised the mass for suspected neoplasm.…”

“…Several radiological and radionuclide modalities such as contrast-enhanced CT scan and CT-guided biopsy,[2] MRI,[8] and gallium scan[12] are available to arrive at a diagnosis. In children, normal thymic tissue is homogeneous and slightly more intense than muscle on T1-weighted MR images and slightly less intense or isointense relative to fat on T2-weighted images.…”

Cervical thymic rebound after cancer treatment

“…Thymic tissue located in the middle or posterior mediastinum is best assessed by MRI because of the modality's multiplanar imaging capability [9]. The relationship to the airway and mediastinal vasculature is well visualized.…”