Successful Management of Retropharyngeal Lymphangioma with Stridor Using Sirolimus: A Case Report

Abstract

Lymphatic malformations (LMs) are one of the congenital malformations of the lymphatic system in the body. The patient usually presents with head and neck swelling, airway compression, and/or airway obstruction. The diagnosis of retropharyngeal LMs can be challenging due to their rare occurrence. We report a case of a five-month-old boy diagnosed with retropharyngeal LMs. He presented with a three-day history of fever, cough, and stridor and was initially treated for acute bronchiolitis. A lateral neck radiograph revealed prevertebral widening, suggesting retropharyngeal collection. The patient’s condition worsened, requiring intubation in the operating room and proceeding with aspirations and drainage. However, the symptoms recurred after a few days, necessitating re-intubation, repeated aspirations and drainage procedures. The patient was intubated, and the neck’s magnetic resonance imaging (MRI) confirmed retropharyngeal LMs. An elective tracheostomy was performed and was treated with sirolimus. The patient had a successful tracheostomy decannulation and showed no recurrence during follow-up.

Introduction

Lymphatic malformations (LMs), previously known as lymphangiomas, are one of the benign causes of head and neck masses. Patients usually become symptomatic at birth and 90% of cases occur under the age of two years old. It comprises about 75% of the head and neck region [1]. Retropharyngeal space is a rare site of LM and this growing mass can cause airway obstruction. This pathology can also be mistaken for a retropharyngeal collection, such as an abscess. In this patient, surgical intervention with antibiotics was given. A tracheostomy is also recommended in patients with retropharyngeal LMs. The dilemma in diagnosing retropharyngeal LMs as it mimics retropharyngeal abscess and can recur after multiple aspirations and drainage. We present a case of retropharyngeal LMs and discuss its clinical features, imaging and treatments.

Case Presentation

A five-month-old boy who was born term via spontaneous vertex delivery with a birth weight of 2.97 kilogrammes and an APGAR score of 9/9/9. He presented with a high-grade fever, chesty cough and noisy breathing for three days. Parents denied any neck swelling. Initially, he was treated for acute bronchiolitis with a differential diagnosis of acute supraglottitis. Lateral neck radiographs demonstrated widening of the prevertebral space, suggesting retropharyngeal collection (Fig. 1). He had worsening respiratory distress with a loud stridor, requiring intubation in the operating room. An examination under anaesthesia was done in the same setting and revealed bulging of the posterior pharyngeal wall. Three mls of hemoserous fluid were aspirated and drained intraoperatively.

Fig. 1.

Lateral neck radiograph (portable) demonstrating widening of prevertebral space

He was able to be extubated a few days after the aspiration. However, one week later, he had reduced oral intake, and breathing difficulties returned. Thus, we decided to re-intubate him. Computed tomography (CT) of the neck with contrast revealed a retropharyngeal collection (HU 15–35) measuring 4.7 cm x 0.8 cm x 3.7 cm (cc x ap x w). Superiorly, the collection extended from the nasopharyngeal region (craniocervical junction) and inferiorly, the extension was at C6 level. Minimal wall enhancement was seen. Laterally, the collection extended into the medial carotid space bilaterally. Examination under anaesthesia and direct laryngoscopy revealed persistent bulging at the posterior pharyngeal wall. Three ml of serous fluids were aspirated. He was kept intubated with endotracheal intubation until a magnetic resonance imaging (MRI) of the neck was performed three days later.

An MRI of the neck showed a well-defined multilobulated and multiloculated cystic lesion in the retropharyngeal space that started from the nasopharynx. It extended into the right carotid space until the inferior margin of the right thyroid lobe (Fig. 2). The craniocaudal extension was approximately six centimetres long. The right carotid space collection partially encased the common carotid artery and insinuated between its bifurcation, but no compression on the vessels was detected. The probable diagnosis was retropharyngeal LMs.

Fig. 2.

Axial and sagittal images of the MRI T2-weighted image showing a multilobulated and multiloculated lesion located within the retropharyngeal space

A tracheostomy was performed and oral sirolimus was started three weeks later. The starting dose of sirolimus was 0.8 mg/m² (a dose of 0.25 mg twice daily), given twice daily. The desired blood levels were between 10 and 15 ng/ml. A clinical, pharmacological, and radiological follow-up was done to assess treatment efficacy. Multiple adjustments to the dose of oral sirolimus were made throughout the course. Initially, he was able to tolerate the initial dose well; however, he developed rash on the face and trunk after increasing the dose to 0.35 mg twice daily (body surface area = 0.39 m²), thus sirolimus was reduced back to 0.25 mg twice daily. A total of 44 weeks of oral sirolimus were prescribed. Despite good compliance, there were also difficulties maintaining blood levels in the therapeutic range and they were often underdosed. The therapeutic blood levels of sirolimus ranged from 2.0 to 4.1 ng/ml.

A CT scan of the neck was done after a 12-month course of oral sirolimus and medication were stopped. The imaging reported a resolved retropharyngeal collection (Fig. 3). Prior to decannulation of the tracheostomy tube, an examination under general anaesthesia and direct laryngoscopy was done and there was no more posterior pharyngeal wall bulging with normal laryngeal structure. The decannulation of the tracheostomy was uneventful. The patient has been followed up for 3 years and shows no symptoms of recurrence.

Fig. 3.

Sagittal view of CT scan neck showing resolved retropharyngeal collection (presence of tracheostomy tube in situ)

Discussion

LMs are low-flow vascular malformations due to abnormal embryologic development of regions of the lymphatic system [2]. It consists of dilated lymphatic channels, forming multiple cysts of variable size and channels. The exact mechanism of this lesion is still unknown. Clinical presentation depends on the site and size of the LMs. Patients can present with cystic masses of the neck and face, macroglossia, swallowing issues, speech difficulties and upper airway obstruction [3]. Other differential diagnoses include congenital and/or acquired cystic lesions, haemangiomas, vascular malformations and lipomas [4].

The management of LMs remains a challenge due to the nature of permeative growth throughout tissue layers. Traditionally, surgical excision has been the first line of treatment [2]. However, due to the proximity of vital structures, it often leads to incomplete excision, recurrence, or damage to the vital structures [4]. The goal of LMs management is to maintain functionality and control the associated symptoms while preserving aesthetic integrity [5]. The type of LMs, size, location, growth trend, and associated symptoms should be considered when treating patients [5, 6]. Other methods of treatment are available for LMs such as sclerotherapy with bleomycin or OK-432, laser therapy and pharmacological treatment [7]. Two cases of retropharyngeal LMs were treated successfully using radiofrequency ablation of LMs via a trans-oral approach and bleomycin sclerotherapy as adjunctive treatment [8].

Sirolimus is an immunosuppressive and antitumour agent that belongs to the mammalian target of rapamycin (mTOR) inhibitor group. The mTOR/PI3K pathway is involved in vascular development and is responsible for cell proliferation, increased angiogenesis, and lymphangiogenesis. Sirolimus will directly inhibit mTOR, thereby preventing downstream protein synthesis and subsequent cell proliferation and angiogenesis. It has an antiproliferative and antiangiogenic effects [5]. Recent studies showed the efficacy of sirolimus in managing large, complicated LMs of the head and neck [3, 5, 9]. Thus, we decided to use sirolimus in managing our patient. Overall, 80.4% of subjects had improvement in radiologic imaging and reduced symptoms over a median period of 10 weeks [10]. According to toxicity data, the most common side effects caused are blood or bone marrow toxicities (27%), metabolic or laboratory toxicities (3%) and pulmonary or upper respiratory toxicities (2%) [5]. Even in neonates, sirolimus was well tolerated with minor side effects [10].

Conclusion

Retropharyngeal LMs is a rare cause of stridor and respiratory distress in children. Physicians should consider retropharyngeal LMs as a possible diagnosis in similar scenarios to ensure prompt recognition and correct treatment.

Funding

No funding has been taken from any sources.

Declarations

Conflict of Interest

None.