Ectopic cervical thymus in children: Clinical and radiographic features

Abstract

Objectives: Ectopic thymus is rare and can be a diagnostic challenge. This study evaluated the management of children radiographically diagnosed with ectopic cervical thymus.Methods: A retrospective review of 100 patients was performed. Data related to clinical presentation, radiological imaging, pathology, and management were collected. Changes in lesion volume were tracked over time. Clinical characteristics were compared based on lesion location in the neck using analysis of variance modelling.Results: There were 115 lesions with radiographic features of ectopic cervical thymus (15 children had bilateral lesions). Diagnosis was based on ultrasound in 98% of patients, magnetic resonance imaging in 18%, and computed tomography in 11%. Mean (SD) follow-up duration was 2 (2.2) years. Forty-four percent (51/115) of lesions involved the thyroid gland, 29% (33/115) were in the central neck but separate from the thyroid, 18% (21/115) had mediastinal extension, and 8% (9/115) involved the submandibular region. Location was unclear for two patients. Submandibular lesions were on average 12.4 cm 3 larger (95% CI, 8.2, 16.6) than mediastinal lesions at diagnosis, P ≤ .001. Volume of thymic tissue decreased over time, from a mean (standard deviation [SD]) volume of 4.3 cm 3 (9.2) at initial ultrasound to 2.7 cm 3 (6.1) at final ultrasound (paired t-test, P = .008). Only two patients required surgery: one for compressive symptoms, and the other to rule out malignancy.Conclusion: Ninety-eight percent of children with ectopic cervical thymus were managed conservatively without issues. We propose a classification system based on location to ease communication among clinicians and to help follow these lesions over time.

Symptomatic Solid Ectopic Cervical Thymus in a 2-Month-Old Infant: Case Report

“…The ectopic thymus can be found in different locations in the neck region as a result of the incomplete descent of the thymic primordia from the 3 rd –4 th pharyngeal pouches to the mediastinum. Lesions that remain in the submandibular region during migration are rarely encountered, compared to lesions located in other cervical areas, and tend to be larger in size, typically diagnosed at a young age ( 4 ). In most cases, ECT is asymptomatic with only 10% presenting with compressive symptoms including dyspnea, hoarseness, stridor, dysphagia, and pain ( 5 ).…”

“…In rare cases, cytopathological examination with FNAB can lead to a certain diagnosis. Some authors refuse to perform FNAB in children because of its controversial diagnostic benefits and general anesthetic requirements ( 4 , 7 ). As the lesion was large, FNAB was performed without general anesthesia in our case.…”

“…In the recent years, the conservative approach is more accepted in asymptomatic ECT regardless of its location. Purcell et al ( 4 ) proposed a classification based on its location in the neck and claimed that most ectopic thymus are intrathyroidal or in the central neck. In the referred study, only 9% of the cases were in the submandibular region.…”

“…In the referred study, only 9% of the cases were in the submandibular region. Furthermore, lesions located in the submandibular region were larger in size, mostly solid and did not show significant change in size over time ( 4 ). If ECT is incidental or there are no symptoms at the time of examination, it is reasonable to follow-up the patient without any surgical intervention.…”

Scans propagating exponential workload (SPEW)

“…The thymus is a lymphatic organ that arises from the third and fourth pharyngeal pouch, similar to the parathyroid glands. It migrates caudally along the thymopharyngeal duct, and ectopic thymic tissue can occur at various points along this descent, as well as around the major vessels 2 . Remnant cervical thymus can present at any age and has been reported in more than two‐thirds of children; it tends to increase in size during childhood before involution occurs eventually in adolescence 2,3 .…”