A Child With a Lateral Neck Mass

Lateral neck masses in children fall into 3 broad categories: congenital, inflammatory, and neoplastic. The differential for a soft, compressible, congenital lateral neck mass includes most commonly, branchial cleft or dermoid cysts, along with ranulas, superior mediastinal cysts, pharyngoceles, laryngoceles, and vascular anomalies including hemangiomas, vascular malformations, or phlebectasias. ¹ We present a lateral neck mass that was initially diagnosed as a branchial cleft cyst but was later correctly diagnosed as a lymphatic malformation (LM) and was treated nonsurgically.

A 6-year-old female was referred for a right neck mass. She was a full-term child without previous hospitalizations or surgeries. Examination revealed a 4-cm discrete, soft, compressible mass in the right lateral neck posterior to the middle one-third of the sternocleidomastoid muscle, extending inferiorly to the supraclavicular fossa. A computed tomography (CT) neck with contrast showed a well-circumscribed, fluid-filled, cystic mass, posterior, and deep to the right sternocleidomastoid, extending from the level of the hyoid superiorly to the clavicle inferiorly (Figure 1) with medial displacement and compression of the right internal jugular vein and right lobe of the thyroid. A magnetic resonance imaging (MRI) showed a septated, macrocystic mass with blood-fluid levels (Figure 2), and the diagnosis of macrocystic LM was made that was amenable for sclerotherapy. She underwent sclerotherapy under general anesthesia with a total of 500 mg of doxycycline and 1 mL of 3% Sotradecol (STS) in foam, which she tolerated without complications. At 1-month follow-up, no residual LM was palpated.

Figure 1.

Axial section of a CT neck with contrast revealing a homogenous, fluid-filled, nonenhancing cystic appearing mass (solid arrow) that is posterior to the sternocleidomastoid muscle on the right (star). CT indicates computed tomography.

Figure 2.

A, Axial section of a T1-weighted MRI without contrast exhibiting a macrocystic lymphatic malformation with fluid–fluid levels secondary to contained blood products (solid arrow). B, Postcontrast MRI shows no enhancement or flow voids (star) which are seen in venous malformations and arteriovenous malformations, respectively. MRI indicates magnetic resonance imaging.

Lymphatic malformations are congenital, low-flow vascular anomalies filled with chyle that consist of collections of abnormal lymphatic vessels composed of normal appearing, flattened endothelial layers. ^2,3 First described in 1843 by Werhner, these lesions were originally termed cystic hygromas or lymphangiomas. They were reclassified as LMs by the International Society for the study of vascular anomalies. ² Lymphatic malformations can present as late as early childhood, though up to 60% are noted at perinatally and almost 90% by the age of 2. ² The majority occur in the head and neck and fall into 3 categories: marocystic where all loculations are >2 mL, microcystic where all loculations are <2 mL, and mixed lesions. ³ Lymphatic malformations grow proportionally with the child, lack the proliferative phase of hemangiomas, and are associated with continued, steady growth rather than spontaneous regression. ⁴

Lymphatic malformations typically exist as soft, easily compressible, cystic lateral neck masses, similar to branchial cleft cysts, dermoid cysts, and other vascular malformations. ¹ Unlike venous malformations or air-filled anomalies such as larynogceles and pharyngoceles, LMs will not increase in size with Valsalva and are not compressible. They also lack the bruit that is characteristic of high-flow vascular malformations. ³ Lymphatic malformations are typically asymptomatic, but they can cause respiratory obstruction or dysphagia because of their location and size. ⁴

Ultrasound and MRI are the first-line imaging studies, while CT and angiography have no clinical role in the evaluation of LMs. ⁴ Ultrasound with Doppler can differentiate low-flow from high-flow LMs and on MRI they appear as fluid filled, lobulated, and septated lesions of varying sizes, with high signal intensity on T2 imaging and low signal intensity on T1. ² Venous malformations show similar characteristics, however, they enhance on late arterial delayed phase sequences unlike LMs, which do not enhance. Additionally, venous malformations may feature pathognomonic intralesional phleboliths. ³ In contrast, high-flow vascular malformations such as hemangiomas and arterio-venous vascular malformations often show multiple signal flow voids on Magnetic resonance angiography. ²

Historically, the treatment for LMs was primarily surgical, with the goal being complete surgical resection of the LM. ³ This however, led to poor postoperative morbidity and a high rate of recurrences in patients with multifocal or bulky disease. ⁴ Over the past 2 decades, sclerotherapy, which involves the direct percutaneous injection of a sclerosing agent, such as doxycycline, ethanol, bleomycin, ethanolamine oleate, STS, or OK-432 with an 18- to 22-gauge needle into the cystic lesions, has become a mainstay of treatment. ⁴ During this time, there has also been a shift in the goals of therapy, from complete excision to that of improving function and symptom burden. Several studies have shown a high rate of excellent outcomes with sclerotherapy or surgical excision for macrocystic lymphatic malformations, with a 76% to 95% success rate. ³ Microcystic lesions, however, respond poorly to both types of treatment and often require several procedures. ¹ In our case, our patient’s macrocystic lesion was treated with both doxycycline and STS sclerotherapy with excellent results.

More recently, several options for the medical management of LMs have been identified. Sirolimus or rapamycin, an Mammalian target of rapamycin inhibitor, has shown success in treating a wide variety of vascular malformations, including LMs. ⁵ Additionally, there have been several case series studying the effects of sildenafil on the size of LMs. However, the outcomes have been mixed, ranging from complete response to no appreciable decrease in the size of microcystic LM. ⁵

This case highlights the need to consider vascular malformations when evaluating lateral neck masses even in older children. These may determine the appropriate diagnostic imaging studies as well as potentially prevent unnecessary surgeries when treating these masses.