Partial Thymectomy during Tracheostomy for Superior Herniation of Normal Mediastinal Thymus in a Patient with Larsen Syndrome: A Case Report.

INTRODUCTION

Superior herniation of the mediastinal thymus is a rare cause of neck mass, characterized by intermittent migration of normal thymic tissue into the suprasternal region due to increased intrathoracic pressure. Generally, thymus resection is discouraged to avoid inducing athymia and subsequent immunodeficiency in the child. To date, no prior cases of tracheostomy combined with partial thymectomy have been reported. We present a case in which partial resection of the thymus was necessary to facilitate a tracheostomy.

CASE PRESENTATION

A 3-month-old female infant diagnosed with Larsen syndrome, a rare congenital connective tissue disorder, presented with respiratory failure necessitating mechanical ventilation at birth. Despite successful extubation and subsequent management with noninvasive positive pressure ventilation, she experienced recurrent episodes of apnea and oxygen desaturation. Examination revealed an anterior midline neck swelling, synchronized with respiratory movements, originating from the suprasternal notch. Ultrasound, computed tomography, and magnetic resonance imaging of the neck confirmed the presence of a normal mediastinal thymus extending into the suprasternal region. Given the risk of upper airway stenosis after the otolaryngological evaluation, an early tracheostomy under general anesthesia was planned. Upon incising the thickened cervical fascia, the thymus was visualized on the anterior surface of the trachea. The thymus and its surrounding adhesions were separated, with resection of the upper pole, followed by closure of the hernia orifice. The tracheostomy was then performed as planned. The postoperative course was uneventful, marked by gradual respiratory improvement and resolution of the intermittently visible swelling during inspiration. Cannula exchanges were completed without complications, and the patient was discharged home with a heat moisture exchanger 3 months after surgery.

CONCLUSIONS

We encountered a case of superior herniation of the normal mediastinal thymus in a patient with Larsen syndrome. While speculative, connective tissue abnormalities may contribute to this condition. In cases requiring tracheostomy, partial thymectomy and closure of the hernia orifice may be necessary to maintain fistula patency postoperatively.