Ectopic Thymus: An Unusual Case of Subglottic Mass

Abstract

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.

Ectopic thymic tissue in subglottis of children: evaluation and management

“…CT scan as the criterion standard for radiological diagnosis could be suggested when ultrasound results cannot provide a hint to make a definitive diagnosis. 6 The feature of uniform low-density mass with regular edges is shown in CT scan. 20 , 22 A normal thymus may be barely visible on Positron Emission Tomography (PET) scans.…”

“…Theoretically, an ectopic thymus could occur in any other location outside the normal descend pathways, such as pharynx, trachea, posterior neck or mediastinum, or esophagus, 6 where subglottic ectopic thymus is a rare condition. A total of 20 children with cervical thymic remnant were summarized from 1975 to 2006 at Cincinnati Children’s Hospital Medical Center, none of which were in the subglottic lesion.…”

“…Basic information and characteristics of these cases were summarized in Table 1 with adding our case in this study. 5 , 6 , 8 , 9 , 10 , 11 Noteworthily, it is the first time to report a highly suspected subglottic ectopic thymus patient before surgical intervention.…”

Solid Ectopic Cervical Thymus: A Case Report

“…Ectopic thymus is a rare, typically benign pediatric condition in which the thymic tissue is located at an unusual site along its migration route, known as the thymopharyngeal canal [ 2 ]. It occurs most commonly in the submandibular triangle, or in the lateral neck, which is called ectopic cervical thymus (ECT) [ 3 ].…”

“…It occurs most commonly in the submandibular triangle, or in the lateral neck, which is called ectopic cervical thymus (ECT) [ 3 ]. In the majority of cases, ectopic thymus presents as a cystic mass, while in fewer cases, it presents as a solid mass [ 2 ].…”