Retropharyngeal Aberrant Thymus

Abstract

ABSTRACT. Introduction. Upper airway obstruction from a retropharyngeal mass requires urgent evaluation. In children, the differential diagnosis includes infection, trauma, neoplasm, and congenital abnormalities. Aberrant cervical thymic tissue, although occasionally observed on autopsy examination, is rarely clinically significant. We present the case of an infant with respiratory distress attributed to aberrant thymic tissue located in the retropharyngeal space.Case. A 6-week-old infant was brought to the emergency department for evaluation of stridor associated with periodic episodes of cyanosis. Lateral neck radiograph revealed widening of the retropharyngeal soft tissues. The patient's symptoms did not improve with intravenous ampicillin-sulbactam. Magnetic resonance imaging (MRI) performed on the seventh day of hospitalization revealed a retropharyngeal mass that extended to the carotid space. The mass was easily resected using an intraoral approach. Microscopic examination demonstrated thymic tissue. A normal thymus was also observed in the anterior mediastinum on MRI. The patient recovered uneventfully and had no further episodes of stridor or cyanosis.Discussion. Aberrant cervical thymic tissue may be cystic or solid. Cystic cervical thymus is more common, and 6% of these patients present with symptoms of dyspnea or dysphagia. Aberrant solid cervical thymus usually presents as an asymptomatic anterior neck mass. This case is unusual in that solid thymic tissue was located in the retropharynx, a finding not previously reported in the English literature. Additionally, the patient presented in acute respiratory distress, and the diagnosis was confounded by the presence of mild laryngomalacia. In retrospect, our patient likely had symptoms of intermittent upper airway obstruction since birth. The acute respiratory distress at presentation was likely the result of laryngomalacia exacerbated by the presence of aberrant thymic tissue and a superimposed viral infection.Aberrantly located thymic tissue arises as a consequence of migrational defects during thymic embryogenesis. The thymus is a paired organ derived from the third and, to a lesser extent, fourth pharyngeal pouches. After its appearance during the sixth week of fetal life, it descends to a final position in the anterior mediastinum, adjacent to the parietal pericardium. Aberrant thymic tissue results when this tissue breaks free from the thymus as it migrates caudally. Therefore, aberrant thymic tissue may be found in any position along a line from the angle of the mandible to the sternal notch, and in the anterior mediastinum to the level of the diaphragm. In an autopsy study of 3236 children, abnormally positioned thymic tissue was found in 34 cases (1%). The aberrant thymus was most often located near the thyroid gland (n ‫؍‬ 19 cases) but was also detected lower in the anterior neck (n ‫؍‬ 6 cases), higher in the anterior neck (n ‫؍‬ 8 cases), and at the left base of the skull (n ‫؍‬ 1 case). The presence of thymic tissue in the retropharyngeal ...

Cervical thymic remnants in children

“…Compressive symptoms are commonly due to a mediastinal component to the mass, and about half of all cervical thymic cysts extend into the mediastinum [3,7,24]. If present, a retropharyngeal component to the mass may cause dysphagia, as was the case in our series, and/or upper airway obstruction [18,22,25]. Rarely, as was demonstrated in our series, cervical thymic cysts present with secondary infection [26].…”

CHARGE (Coloboma, Heart Defect, Atresia Choanae, Retarded Growth and Development, Genital Hypoplasia, Ear Anomalies/Deafness) Syndrome and Chromosome 22q11.2 Deletion Syndrome: A Comparison of Immunologic and Nonimmunologic Phenotypic Features

“…In some patients, thymic tissue may reside in extrathymic locations such as the neck or the retropharyngeal space enabling patients to generate T-cells 27 . Patients can have decreased CD3+ and CD4+ T-cell counts, which are most severe during the first year of life, but then often improve 28,29 .…”

Inspiratory stridor and dysphagia in two newborn infants caused by ectopic thymus tissue

“…There is a male predominance of almost 3:1 [9,15]. Most of the aberrant thymic masses are asymptomatic [2], but they can cause severe respiratory compromise and dysphagia by intrinsic obstruction of the aerodigestive organs [5,16]. Additional symptoms are stridor, hoarse- ness, vocal cord paralysis, or cervical pain [11,14].…”