Pediatric Neck Masses

Anatomy & Pathophysiology:

While the evaluation of a neck mass in an adult typically focuses on ruling out malignancy, malignant tumors are significantly less common in the pediatric population. The differential diagnosis of a pediatric neck mass includes pathologies less frequently encountered in adults, such as congenital malformations and infections. The first step in evaluating a pediatric neck mass is determining whether it is congenital or acquired.

Congenital neck masses:

The more commonly encountered congenital neck masses include branchial cleft cysts, thyroglossal duct cysts, teratomas, dermoid cysts, and lymphatic or vascular malformations. Other, less common congenital neck masses include thymic cysts and laryngoceles.

Branchial Cleft Cysts

Branchial cleft cysts are thought to develop from failure of obliteration of the pharyngobranchial ducts. They are divided into four subtypes, with second branchial cleft anomalies being most common and the other three types being rare. First branchial cleft anomalies are located on the face or near the auricle. They are further subdivided in to two types: type I first branchial cleft cysts are ectodermal duplications of the external auditory canal, while type II first branchial cleft cysts contain ectodermal and mesodermal tissue. Type II anomalies are usually located below the angle of the mandible and pass through the parotid gland. Because of their location, first branchial cleft anomalies may involve the facial nerve.

Second branchial cleft anomalies are usually located below the angle of the mandible at the anterior border of the sternocleidomastoid. A tract may be present that opens into the tonsillar fossa. Third branchial cleft anomalies are also located in the neck anterior to the sternocleidomastoid and open into the pyriform sinus of the hypopharynx. Fourth branchial cleft anomalies are rare and typically terminate in the left side of the thyroid gland.

Thyroglossal Duct Cysts

If a child presents with a midline congenital neck mass, thyroglossal duct cyst (TGDC) and dermoid cyst should be considered. In normal development, the thyroid gland descends from its initial position at the foramen cecum of the tongue into the neck. When the descent tract persists, a TGDC may form, usually near the level of the hyoid bone. Occasionally, TGDCs may be lateral to the midline, in which case, they must be distinguished from branchial cleft anomalies. Up to 45% of TGDCs contain thyroid tissue. An ultrasound of the neck is performed prior to removal of a TGDC to confirm the presence of a normal thyroid gland as, occasionally, the patient’s only functional thyroid tissue may be located in the TGDC.

Teratomas and Dermoid Cysts

Teratomas and dermoid cysts are congenital growths that are composed of cells from all three germ layers. Teratomas form from pluripotent cell populations, while dermoid cysts form when epithelium is trapped or implanted in deeper tissue. Teratomas in the head and neck account for less than 5% of all teratomas. An association with maternal polyhydramnios has been documented. In the neck, dermoid cysts are usually located in the midline and are attached to the overlying skin. They may occur in the submental area, periorbital area, or in the nose.

Lymphatic Malformations

Vascular malformations may be slow- or fast-flow. Unlike hemangiomas, these anomalies do not involute with time and continue to grow as the child grows. Lymphatic malformations are considered slow-flow vascular malformations and may be macrocystic, microcystic, or mixed (macro- and microcystic). Lymphatic malformations result when a lymphatic space fails to connect to the remainder of the lymphatic system and the venous system.

Sternocleidomastoid Tumor of Infancy

The most common neck mass in a newborn is the sternocleidomastoid tumor of infancy (also called congenital torticollis or fibromatosis colli.) The baby presents with a hard mass within the midportion of the sternocleidomastoid muscle, causing the ipsilateral ear to tilt toward the shoulder and the face to turn toward the contralateral shoulder. Secondary deformational plagiocephaly (misshapen head due to repeated pressure on the developing cranium) can result. In most cases, the torticollis resolves spontaneously or with physical therapy before 1 year of age. In rare cases, the muscle must be surgically divided to allow the infant's head to turn easily from side to side.

Acquired Neck Masses

Acquired pediatric neck masses may be divided into infectious, inflammatory, and neoplastic causes.

Reactive Cervical Lymphadenopathy

Cervical lymphadenopathy can result from viral infection with a number of viruses, including adenovirus, rhinovirus, coxsackievirus, Epstein-Barr virus, and human immunodeficiency virus. Cervical lymph nodes may also be infected by bacteria, causing suppuration. Staphylococcus aureus and group A Streptococcus are the most common organisms and infection is frequently located in the submandibular region. Other bacterial infections resulting in cervical adenopathy include cat scratch disease (Bartonella henselae infection) and mycobacterial infections . Mycobacterial infection in the neck most commonly occurs in the anterior superior neck, although other regions may also be infected. Parasitic or fungal infections of the head and neck are rare.

Inflammatory Neck Masses

Inflammation may occur with systemic diseases such as Kawasaki disease (a vasculitis that may present with nonpurulent cervical lymphadenopathy that is usually unilateral) or sarcoidosis.

Neoplasm

Cervical neoplasms are rare in children; benign growths include lipomas, neurofibromas, thyroid adenomas, or pleomorphic adenomas of the salivary glands. Malignant neck masses include lymphoma, rhabdomyosarcoma, neuroblastoma, thyroid carcinoma, malignant salivary gland tumors, and nasopharyngeal carcinoma. Lymphoma is the most common pediatric neck malignancy. Hodgkin's disease is more commonly seen in the neck than non-Hodgkin's lymphoma.

This chapter will primarily focus on congenital neck masses that are surgically treatable. Detailed discussion of many of the systemic infections and diseases that cause cervical lymphadenopathy is beyond the scope of this text; however, selected references are provided at the conclusion of the section.

Epidemiology:

Pediatric neck masses are benign in the vast majority of cases, and up to 50% may be congenital in nature. Thyroglossal duct cysts account for up to one-third of all congenital neck masses and most commonly present during the first decade of life. Reactive lymphadenopathy is the most common cause of cervical lymphadenopathy in children

Natural History:

Branchial cleft cysts and tracts are typically asymptomatic unless they become infected, which may occur after an upper respiratory illness. While infection may resolve with antibiotics, recurrent infection is common. Additionally, growth of the cyst may result in mass effect causing dysphagia and airway obstruction. Similarly, thyroglossal duct cysts are usually asymptomatic unless infected. Rarely, TGDCs may harbor thyroid carcinoma. Carcinomatous transformation is also possible, although very rare, in dermoid cysts and cervical teratomas. Continued growth of teratomas is concerning for compressive effects and may result in dysphagia and airway obstruction.

Presentation:

Branchial cleft anomalies and thyroglossal duct cysts typically present upon infection, usually after an upper respiratory illness. Symptoms may include increase in size, tenderness, and drainage from an associated sinus tract. Teratomas, dermoid cysts, and lymphatic malformations are generally painless; they are typically brought to attention due to cosmetic deformity. Depending on the size and location of the mass, patients may also present with obstructive symptoms, such as dysphagia or stridor.

Infections resulting in neck masses are usually accompanied by other local and systemic symptoms associated with the underlying cause. For instance, reactive viral lymphadenopathy may be associated with symptoms of upper respiratory infection. Epstein-Barr virus infection generally causes enlargement of other lymphoid tissue, such as the tonsils, as well as general malaise. Suppurative lymphadenopathy is typically marked by fever and a painful neck mass.

Lymphoma can present with an asymptomatic neck mass as well as systemic symptoms, including fever, chills, night sweats, weight loss, and malaise.

Differential Diagnosis of Pediatric Neck Masses:

Evaluation:

History

The patient history may help to determine the cause of a neck mass, particularly in cases of infection. The time course and growth pattern of the mass should be elucidated, and will assist with differentiating congenital from acquired masses. Temporal association of onset or exacerbation with recent illness, travel, or exposure should also be determined. In particular, contact with cats (particularly kittens) increases suspicion for cat scratch disease or toxoplasmosis in the correct clinical context, while exposure to persons with mycobacterial or human immunodeficiency virus infection should prompt testing for those infections. The presence of systemic symptoms, such as fever or malaise, also suggests an infectious etiology.

Physical Examination

The physical examination should characterize the size, consistency, mobility, and location of the mass, as well as whether it is tender or appears inflamed. Although the physical appearance of the mass is not usually sufficient for diagnosis, certain features may suggest particular diagnoses. For example, a midline mass near the hyoid that moves up and down when the patient swallows or protrudes the tongue is likely to be a thyroglossal duct cyst. Likewise, lymphatic malformations are typically soft, smooth, compressible, and transilluminate. Hyperplastic lymph nodes up to 2 cm in size are frequently palpable in healthy infants and children. Larger lymph nodes or the presence of additional symptoms (such as pain, infection, or systemic symptoms) warrant further investigation. Physical examination should also include palpation for axillary and pelvic lymphadenopathy and splenomegaly.

Imaging Studies

Radiologic studies are frequently useful in diagnosis as well as treatment planning. Ultrasound is an inexpensive and noninvasive modality that is useful in identifying cystic components of neck masses. If thyroglossal duct cyst is suspected, an ultrasound should also be performed to confirm the presence of normal thyroid tissue prior to excision. Chest x-ray is useful in cases of suspected tuberculosis, sarcoidosis, or malignancy. Where a neck abscess is clinically suspected, but not clear on examination, imaging with ultrasound or computed tomography (CT) may be helpful. CT is also useful for the characterization of vascular malformations. Magnetic resonance imaging (MRI) is the preferred modality for soft tissue visualization and can also be used for evaluation of vascular lesions.

Laboratory Studies

Laboratory studies are primarily useful for diagnosing infectious causes of neck masses. Serologic testing for viral, bacterial, fungal or parasitic pathogens may be performed depending on patient history and clinical suspicion. While tissue culture is the definitive method of diagnosis for mycobacterial infection, skin testing is sensitive for both tuberculosis and atypical mycobacterial infection and provides a faster result when positive.

Biopsy

Fine needle aspiration (FNA) or biopsy is performed in cases of suspected malignancy. In cases of lymphoma, an open biopsy may be necessary even if FNA is diagnostic, in order to determine the histopathologic classification of lymphoma type. FNA or biopsy should not be attempted if there is any possibility that the mass is a vascular neoplasm or malformation; radiographic confirmation should be obtained first in such cases.

Treatment:

Branchial Cleft Cysts

The definitive treatment for branchial cleft cysts is surgical excision. Any active infection should be resolved with antibiotic therapy prior to undertaking surgery. Incision and drainage of infected cysts should be avoided, as scarring can complicate future excision attempts. Excision is typically performed using an external approach; a series of stair-step incisions may be required to trace the cyst tract to its origin. Special care should be taken during excision of a first branchial cleft anomaly, as the tract may be in close proximity to, or involve, the facial nerve.

Thyroglossal Duct Cysts

Thyroglossal duct cysts are also treated with surgical excision. The standard method of excision is the Sistrunk procedure, which is discussed in Sistrunk Procedure. In this procedure, the cyst is removed, along with a cuff of normal tissue that includes the central portion of the hyoid bone. The tract is followed all the way to the tongue base, where it is amputated.

Teratomas and Dermoid Cysts

Teratomas and dermoid cysts are treated by complete surgical excision. Cervical teratomas may be diagnosed prenatally and, if large enough to cause respiratory compromise, may require emergent treatment in the neonatal period. Ex-utero intrapartum treatment (EXIT) is a method whereby the fetus is partially delivered via cesarean section, allowing for an airway to be secured under controlled circumstances. The common indication for an EXIT procedure is fetal airway obstruction as a result of a congenital neck mass.

Lymphatic Malformations

Lymphatic malformations may be excised if cosmetic deformity is pronounced, or if compressive symptoms are present. Often, large lymphatic malformations cannot be completely resected due to involvement of vital structures. In these cases, debulking procedures may be performed to achieve symptomatic relief. Sclerotherapy using various compounds has also been reported as effective in treating macrocystic lymphatic malformations.

Acquired Neck Masses

The treatment of infectious neck masses depends on the causative pathogen. Hodgkin's disease is treated with either chemotherapy or radiotherapy, depending on the histopathologic classification, whereas non-Hodgkin's lymphoma is treated with chemotherapy.

Complications, Prognosis & Follow-Up:

Untreated, branchial cleft anomalies may cause recurrent infections requiring antibiotic therapy or incision and drainage. In a patient who has not previously undergone any neck surgery, branchial cleft cyst excision has a high success rate, with only 3% of patients requiring reoperation. The recurrence rate may be as high as 20% in patients with prior surgical history or history of multiple infections. Complications of branchial cleft cyst excision include incomplete excision and injury to nerves or vascular structures.

Thyroglossal duct cysts may also be prone to recurrent infection if left untreated. A correctly performed Sistrunk procedure in which a sufficient cuff of tissue (that includes the entire tract and middle one-third of the hyoid bone) has been excised has a reported recurrence rate of 3-10%. The recurrence rate is as high as 50% if only a simple cyst excision is performed. Complications of the Sistrunk procedure include incomplete excision, injury to surrounding nerves, and wound infection.

Cervical teratoma is associated with high mortality if not treated emergently. Although excision is typically curative, the prognosis for these patients is often complicated by associated conditions, such as pulmonary hypoplasia and fetal hydrops. Prognosis for patients with teratomas without respiratory compromise is significantly better.

Prognosis for cervical lymphatic malformations depends on a number of factors, such as the size and extent of the malformation and whether it is macrocystic or microcystic. Negative prognostic indicators include microcystic disease, multiple lesions, and extensive or complex lesions. Recurrence rates are high after resection (particularly if the lesion is microcystic), and the risk of injury to local structures is high due to the infiltrative nature of the lesion.