Cervical thymic anomalies-The Texas Children's Hospital experience

Diagnosis and management of ectopic cervical thymus in children: Systematic review of the literature

BACKGROUND/PURPOSE

Ectopic cervical thymus (ECT) is a rare cause of neck swelling in children. Our aim was to evaluate the diagnostic and management challenges of this condition.

METHODS

Systematic review of the literature (1997-2020) using PRISMA guidelines.

RESULTS

A total of 192 cases of ECT were identified. Forty-two cases (4 studies) were excluded because of insufficient data resulting in 150 cases (7 bilateral) in a total of 143 patients. ECT presented as a solid mass in 71 cases (10 incidentally found at autopsy, 33 conservatively managed and 28 excised) and as a cystic mass in 79 cases (all excised). A total of 165 imaging studies in 123 patients were performed (65 ultrasound scans (USS), 51 magnetic resonance imaging (MRI) scans and 49 computer tomography (CT) scans). ECT was diagnosed by imaging in 18.7% (23/123) of patients. Fine needle aspiration cytology or incisional/needle biopsy were performed in 16% (23/140) cases; a correct diagnosis of ECT was obtained in 52% (12/23) of those cases. There were no reports of malignancy in 143 specimens analysed. A normal mediastinal thymus was absent in 2.5% (1/40) of patients investigated.

CONCLUSIONS

ECT is a benign and relatively rare condition in children that is seldom diagnosed on imaging before tissue sampling or surgical excision. ECT might be the only active thymus in 2.5% of cases and careful consideration should be taken prior to its excision in young children. We recommend that ECT should be considered in the differential diagnosis of neck masses in children. Conservative management might be appropriate in selected cases and the presence of a normal mediastinal thymus in the thorax should be investigated before planning surgical excision.

Ectopic cervical thymus in children: Clinical and radiographic features

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 cm³ 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 cm³ (9.2) at initial ultrasound to 2.7 cm³ (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.

LEVEL OF EVIDENCE

4, case series Laryngoscope, 130:1577-1582, 2020.

Cervical Thymic Cyst Around Hypoglossal Nerve

Cervical thymic cyst is rare lesions leading to cervical mass. As it is a rare entity, it might be confused with other congenital neck masses or neoplastic lesions. Preoperative diagnosis is almost impossible. In the present study, a patient who was operated with prediagnosis of branchial cyst and diagnosed with thymic cyst according to the histopathologic examination was presented. A 16-month-old girl was admitted to our clinic with the complaint of growing right neck mass that was realized about 4 months ago. Magnetic resonance imaging (MRI) of the neck demonstrated a rim-enhanced hypointense cystic lesion in the posterior aspect of the submandibular gland, without tracheal right lateral and mid plane on MRI, curving common carotid artery to the medial. Patients underwent surgery under general anesthesia in company with existing findings. Hypoglossal nerve was surrounded by the mass, and the mass was totally resected. The final pathology result was reported as thymic cyst. Cervical thymic masses might be unnoticed in the differential diagnosis of the cervical mass as they are rarely seen entities. Histopathologic examination of the thymus tissue was performed for diagnosis. Surgical excision is the ideal treatment approach and no postoperative recurrence has been reported.

Cystic form of cervical lymphadenopathy. Guidelines of the French Society of Otorhinolaryngology - Head and Neck Surgery (SFORL). Part 1: Diagnostic procedures for lymphadenopathy in case of cervical mass with cystic aspect

OBJECTIVES

The authors present the guidelines of the French Society of Otorhinolaryngology - Head and Neck Surgery Society on diagnostic procedures for lymphadenopathy in case of a cervical mass with cystic aspect.

METHODS

A multidisciplinary work-group was entrusted with a review of the scientific literature on the topic. Guidelines were drawn up, then read over by an editorial group independent of the work-group, and the final version was drawn up. Guidelines were graded as A, B, C or expert opinion, by decreasing level of evidence.

RESULTS

In adults presenting a cystic cervical mass, it is recommended to suspect cervical lymphadenopathy: in order of decreasing frequency, cystic metastasis of head and neck squamous cell carcinoma, of undifferentiated nasopharyngeal carcinoma, and of thyroid papillary carcinoma (Grade C). On discovery of a cystic cervical mass on ultrasound, architectural elements indicating a lymph node and a thyroid nodule with signs of malignancy should be screened for, especially if the mass is located in levels III, IV or VI (Grade A). Malignant lymphadenopathy should be suspected in case of cervical mass with cystic component on CT (Grade B), but benign or malignant status cannot be diagnosed only on radiological data (CT or MRI) (Grade A), and 18-FDG PET-CT should be performed, particularly in case of inconclusive ultrasound-guided fine needle aspiration biopsy (Grade C).

Diagnosis and Management of Cervical Thymic Cysts in Children

We present the case of a 10-year-old boy with the sudden onset of a large, painless left neck mass. Findings on magnetic resonance imaging (MRI) and fine needle aspiration (FNA) biopsy suggest a cystic lesion, most likely of thymic origin. Cervical thymic cysts are a rare form of cervical mass, which are easily overlooked in the differential diagnosis of children presenting with painless neck masses. A combination of CT and MRI investigations can be helpful in differentiating thymic cysts from other congenital and neoplastic masses, but the definitive diagnosis of thymic cyst requires histopathological documentation of thymic tissue. Surgical excision is considered the management of choice for thymic cysts, and no cases of postoperative recurrence have been reported.

Cervical thymic cyst in an adult

Cervical thymic cysts (CTCs) are unusual lesions, representing only 1% of cystic cervical masses. Diagnosis of this condition in adults is even rarer. We report a 34-year-old female who presented with asymptomatic progressively growing left-sided neck swelling. Neck ultrasound (US) showed a large cystic lesion with septation, compressing the ipsilateral vessels. Magnetic resonance imaging (MRI) confirmed the US findings. Surgical excision was performed which subsequently showed findings consistent with CTC. CTC in adult is extremely rare, with few reported cases identified in the literature. Thymic gland anomalies in the neck are the consequences of an arrest in the descent of the gland, sequestration of the thymic tissue, or failure of involution. The diagnosis of this condition is rarely done prior to surgical excision. The clinical presentation, radiologic imaging, surgical findings, and histologic appearance are all essential components to make the correct diagnosis of this very rare differential diagnosis of cystic lateral neck swelling.

Retropharyngeal thymus and parathyroid gland: a case report

Cervical ectopic thymus occurs when thymic tissue arrests during its embryologic descent through the neck to the upper mediastinum. Most often it presents as an asymptomatic neck mass. Rarely does it present with airway compromise, particularly in neonates. A neonate presented with a retropharyngeal mass causing dynamic upper airway obstruction, mimicking a venolymphatic malformation. Ultimately this proved to be aberrant ectopic thymus with an associated parathyroid gland. While there have been isolated reports of thymus or parathyroid in the retropharyngeal space, none of the prior reports found both within the same patient.

Evolution of thymus organogenesis

The thymus is the primary organ for functional T lymphocyte development in jawed vertebrates. A new study in the jawless fish, lampreys, indicates the existence of a primitive thymus in these surviving representatives of the most ancient vertebrates, providing strong evidence of co-evolution of T cells and thymus. This review summarizes the wealth of data that have been generated towards understanding the evolution of the thymus in the vertebrates. Progress in identifying genetic networks and cellular mechanisms that control thymus organogenesis in mammals and their evolution in lower species may inspire the development of new strategies for medical interventions targeting faulty thymus functions.

Transcriptomic analysis supports similar functional roles for the two thymuses of the tammar wallaby

Background

The thymus plays a critical role in the development and maturation of T-cells. Humans have a single thoracic thymus and presence of a second thymus is considered an anomaly. However, many vertebrates have multiple thymuses. The tammar wallaby has two thymuses: a thoracic thymus (typically found in all mammals) and a dominant cervical thymus. Researchers have known about the presence of the two wallaby thymuses since the 1800s, but no genome-wide research has been carried out into possible functional differences between the two thymic tissues. Here, we used pyrosequencing to compare the transcriptomes of a cervical and thoracic thymus from a single 178 day old tammar wallaby.

Results

We show that both the tammar thoracic and the cervical thymuses displayed gene expression profiles consistent with roles in T-cell development. Both thymuses expressed genes that mediate distinct phases of T-cells differentiation, including the initial commitment of blood stem cells to the T-lineage, the generation of T-cell receptor diversity and development of thymic epithelial cells. Crucial immune genes, such as chemokines were also present. Comparable patterns of expression of non-coding RNAs were seen. 67 genes differentially expressed between the two thymuses were detected, and the possible significance of these results are discussed.

Conclusion

This is the first study comparing the transcriptomes of two thymuses from a single individual. Our finding supports that both thymuses are functionally equivalent and drive T-cell development. These results are an important first step in the understanding of the genetic processes that govern marsupial immunity, and also allow us to begin to trace the evolution of the mammalian immune system.

Clinical management of cervical ectopic thymus in children

OBJECTIVE

Cervical ectopic thymus (CET) is an extremely uncommon etiology of a neck mass in an infant. The aim of this study was to study and analyze the clinical manifestations, management principles, and pathological diagnosis of CET.

METHODS

From 1995 to 2010, a total of 25,237 cases of head and neck lesions were treated in the Department of Oral and Maxillofacial Surgery, Shanghai Ninth People's Hospital. Among these huge numbers of lesions, there were only 3 cases of pathological-diagnosed CET presenting as neck masses. These 3 rare cases were interesting, and here, we report their clinical management and pathological diagnosis.

RESULT

Three patients had a pathological diagnosis of CET. Their ages ranged from 4 months to 4 years. Clinically, all 3 patients presented with a painless neck mass and received surgical resection. Pathological diagnoses are based on hematoxylin and eosin and immunohistochemical staining.

CONCLUSION

Painless swelling or neck mass is the major complaint for CET. Radiologic imaging can help determine the extent of the mass and relationship with adjacent structures. Surgery with frozen section remains the main method for pathological diagnosis and management.