Ectopic thymus presenting as a subglottic mass: diagnostic and management dilemmas

Ectopic thymic tissue in subglottis of children: evaluation and management

OBJECTIVES

Ectopic thymic tissue in the subglottis is an extremely rare disease that causes airway obstruction. Few cases reported were accurately diagnosed before surgery.

METHODS

A case of a 2-year-old boy with airway obstruction caused by a left subglottic mass was reported. The presentation of radiological imaging, direct laryngoscopy and bronchoscopy, pathology, and surgical management were reviewed. An extensive search in PubMed, EMBASE, Web of Science, Google Scholar, and EBSCO of English literature was performed without a limit of time.

RESULTS

Besides our case, only six cases were reported since 1987. The definitive diagnosis on these patients were made with the findings of pathology, of which, five were ectopic thymus and two were ectopic thymic cysts. Our case was the only one with a correct suspicion preoperatively. Four cases underwent open surgical resection, and two cases underwent microlaryngeal surgery, while one deceased after emergency tracheostomy. No recurrences were found by six patients during the follow-up after successful treatments.

CONCLUSION

Ectopic thymus is a rare condition, infrequently considered in the differential diagnosis of subglottic masses. Modified laryngofissure may be an effective approach to removing the subglottic ectopic thymus and reconstructing the intact subglottic mucosa.

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.

Subglottic ectopic thymus mimicking airway haemangioma

Subglottic haemangioma presents as progressive obstruction in the neonatal and infantile airway, with a soft lesion seen during endoscopy. Diagnosis is based on macroscopic findings, biopsy is not usually performed and propranolol is first-line treatment. In contrast, ectopic thymus is a rare differential diagnosis for subglottic mass made by histopathological examination after excision or autopsy. In this article, we present a case of an infant with a subglottic lesion with endoscopic features consistent with haemangioma. After initial clinical response to propranolol, the patient represented with progressive stridor no longer responding to therapy. Open excision of the lesion was performed, and histopathology revealed ectopic thymus tissue. In this case, ectopic thymus tissue mimicked the presentation of subglottic haemangioma, and confirmation bias persisted due to an apparent initial clinical response to treatment with propranolol. In cases of subglottic mass refractory to medical treatment, excision of the lesion should be considered.

Ectopic Thymus: An Unusual Case of Subglottic Mass

Objectives:

The aim of our study is to report a case of a child with subglottic thymus that was suspected during diagnostic work-up for severe airway obstruction, excised surgically and confirmed with final histopathological examination. Moreover, we performed a narrative literature review to outline clinical and diagnostic features of this rare condition and to report suggestions for the management of subglottic masses.

Methods:

We report the case of a 7-month-old boy who was admitted to our Pediatric Airway Team Unit due to a history of worsening biphasic stridor and recurrent episodes of upper airway obstruction. The successful diagnostic work-up and a narrative literature of analogous cases of subglottic thymus were reported.

Results:

Ectopic thymus is a very rare condition in which thymic tissue is found outside the normal pathway of its embryonic migration. It usually presents as a cystic or, more rarely, solid mass, showing an indolent course toward spontaneous involution. In some cases, however, it becomes symptomatic exerting compression on surrounding vital structures. Due to its rarity, the initial diagnosis is normally mistaken with inflammatory diseases or malignancies and the definitive diagnosis is only achieved after histological examination of the excised specimen. To our knowledge, only four other cases of subglottic ectopic thymic tissue have been reported in the English literature so far and the diagnosis has never been suspected preoperatively.

Conclusion:

It is mandatory to consider ectopic thymic tissue in the differential diagnosis in children presenting with airways obstruction in order to prevent unnecessary, extensive, and exploratory surgery.

Difficult intubation in a neonate: a diagnostic dilemma

Difficult intubation in neonates has innumerable aetiologies. It especially poses a formidable challenge to save a newborn baby immediately after birth where antenatal details are unavailable. A late preterm neonate was born limp and apnoeic. Several attempts to intubate the baby were unsuccessful. Possibility of subglottic obstruction was considered. The baby died of severe perinatal asphyxia. Autopsy showed a mass around the airway which turned out to be ectopic thymus on histopathology. Ectopic thymus can present as periglottic mass without externally visible cervical swelling and can cause difficult intubation which may lead to serious adverse outcome including death if not anticipated early and managed accordingly.

Ectopic Thymic Cyst of the Subglottis: Considerations for Diagnosis and Management

OBJECTIVES

To share the diagnostic and management challenges created by an extremely rare airway lesion-the subglottic ectopic thymic cyst.

STUDY DESIGN

Case report and literature review.

METHODS

We review the presentation, management, and clinical course of an infant who presented with a subglottic mass that was histologically confirmed as a thymic cyst. A brief literature review supplements the case presentation Results: We present the third described case of an ectopic thymic cyst presenting as a subglottic mass. The differential diagnosis of subglottic masses in neonates consists primarily of subglottic hemangioma and mucous retention cysts. Otolaryngologists must be prepared for unexpected findings when dealing with critical airways. We compare the presentation and management of our patient with the 2 previously described cases. We propose an embryologic theory for the origin of these rare lesions.

CONCLUSIONS

An ectopic thymic cyst is a rare and unexpected cause of neonatal stridor. Management of pediatric airway lesions must allow for unexpected findings at the time of diagnostic and therapeutic endoscopy. The appropriate management of subglottic thymic cysts is poorly defined, but close surveillance for recurrence is mandatory.

Assessment of the thymic morphometry using ultrasound in full-term newborns

PURPOSE

The size of thymus is variable and depends on age of the individual. Thymus undergoes its maximum development at the time of birth, when it also has the greatest relative weight. The aim of our study was to compare the two ways of expressing the size of the newborns' thymus, the Thymus index and estimated volume of thymus.

METHODS

The examined group consisted of 212 full-term newborns from Slovakia, Europe. We estimated the length, width and thickness of the left and right lobes. We used these data to calculate the approximate volume of the thymus. We also expressed size of the thymus as a multiple of the transverse diameter of the cranial part of the thymus and the sagittal area of the larger lobe of the thymus, the so-called Thymus index. Bilateral differences in thymus lobes' sizes, as well as the thymus' sizes between sexes and among the newborns of different types of birth were also analysed.

RESULTS

Our results show that (1) the left thymus lobe is longer and thicker than the right lobe; (2) the Thymus index and the estimated volume of the thymus have a strong significant and positive correlation; (3) boys reach significantly higher values of the Thymus index than girls; and (4) when comparing the differences in the thymus size between the newborns born in two different ways (spontaneous and operatively), no significant difference was discovered.

CONCLUSION

Ultrasound examination is safe, effective and suitable for simple assessment of the thymus size, which has a great variability in children. In other hand, the use of the Thymus index in everyday clinical practice is limited due to different mean values in a number of studies.

Ectopic intrathyroidal thymus misdiagnosed as a thyroid nodule: sonographic appearance

An 11-year-old boy under suppression therapy for a solitary thyroid nodule was referred for sonographic examination. The diagnosis had been made at another institution, based only on sonography without cytopathologic verification. A small fusiform lesion, which was homogeneously hypoechoic with diffuse bright internal echoes, was demonstrated in the right lower pole of the thyroid. A normal elongated thymus with a cervical component was then found connected to the thyroid with an accessory lobe, which was embedded in the lower thyroid pole mimicking a solitary nodule. We discuss the developmental abnormalities of the thymus and their clinical significance in childhood with a brief review of the literature.

Evidence for a functional second thymus in mice

The thymus organ supports the development of T cells and is located in the thorax. Here, we report the existence of a second thymus in the mouse neck, which develops after birth and grows to the size of a small lymph node. The cervical thymus had a typical medulla-cortex structure, was found to support T cell development, and could correct T cell deficiency in athymic nude mice upon transplantation. The identification of a regular second thymus in the mouse may provide evolutionary links to thymus organogenesis in other vertebrates and suggests a need to reconsider the effect of thoracic thymectomy on de novo T cell production.