OFFICIAL ABP TOPIC:

Understand the differential diagnosis and evaluation of a neck mass

BACKGROUND

Pediatric neck masses are a common clinical finding that can cause significant anxiety for patients and families. While most of these masses are benign, timely recognition of red flags is critical for identifying serious conditions, such as malignancy or infection, and providing appropriate management.

DIFFERENTIAL DIAGNOSIS OF NECK MASSES

CONGENITAL NECK MASSES

• Branchial cleft cysts: The most common congenital neck masses, accounting for 20-30% of pediatric neck masses. Usually present in late childhood or adolescence when infected.
• Thyroglossal duct cysts: Midline masses, often presenting after an upper respiratory infection. Move with swallowing or tongue protrusion, reflecting their connection to embryologic thyroid migration.
• Cystic hygromas: Soft, compressible, nontender masses in the posterior triangle of the neck. These lymphatic malformations often transilluminate and can compromise the airway when rapidly enlarging due to infection or hemorrhage.
• Other rare masses: Dermoid cysts (midline, arise from trapped epithelial elements), thymic cysts (persistent thymic remnants), laryngoceles (herniation of the laryngeal saccule), and teratomas (contain all three germ layers, potentially causing airway compromise).

ACQUIRED NECK MASSES

• Inflammatory: Reactive lymphadenopathy due to recent infections or local inflammation.
• Infectious: Viral causes (EBV, CMV) may lead to generalized lymphadenopathy. Bacterial causes (e.g., Staphylococcus, Streptococcus) often present with unilateral tender, erythematous nodes. Bartonella (cat-scratch disease) may cause regional lymphadenitis after exposure to cats or fleas.
• Neoplastic: Lymphoma is the most common cause of malignant head and neck masses, often characterized by painless, firm, fixed, and rapidly enlarging nodes. Rhabdomyosarcoma, neuroblastoma, leukemia, and thyroid carcinoma are other common malignancies that can cause neck masses.

EVALUATION OF NECK MASSES

HISTORY

• Recent URI or infections suggest an infectious or reactive cause, such as lymphadenitis. Repeated history of similar swelling after URI infections suggests a congenital mass.
• Constitutional symptoms (e.g., fever, night sweats, weight loss, bone pain) raise suspicion for malignancy like lymphoma or leukemia.
• Airway symptoms (stridor, vocal changes, dysphagia, drooling) may indicate airway compression from rapidly expanding masses like cystic hygromas or mediastinal tumors.
• Exposures to animals (e.g., cats for Bartonella) or travel history (e.g., TB-endemic areas) guide the infectious differential diagnosis.
• History of irradiation to the neck raises the risk of malignancy.

PHYSICAL EXAM

Exam should include a complete ENT exam, evaluation of all lymph nodes, cardiorespiratory exam, abdominal exam (including assessment for hepatosplenomegaly), skin exam, and cranial nerve exam.

• Determine anatomic location: Midline masses that move with swallowing are more likely to involve the thyroid (e.g. thyroglossal duct cysts), while lateral or supraclavicular masses are more likely to be enlarged lymph nodes.
• Consistency and mobility: Fixed masses suggest malignancy or deep infection. Tender, erythematous, and fluctuant nodes are likely due to bacterial infection.
• Transilluminating masses suggest cystic hygroma or fluid-filled masses.

DIAGNOSTIC EVALUATION

The evaluation of neck masses should be based on history and physical:

• If a thyroid mass is suspected, obtain TSH/T4 and thyroid ultrasound. Use fine needle aspiration to evaluate concerning masses on thyroid ultrasound.
• If malignancy is suspected, obtain CBC with differential, CMP, ESR/CRP, LDH, uric acid, CXR and refer for possible excisional biopsy.
• If mass is infected and draining, send fluid for Gram stain and culture.
• If bacteremia is suspected due to fever, obtain CBC and blood culture.
• If mass is suspected to be a single enlarged lymph node with low suspicion for malignancy or infection, consider observation for 3-4 weeks. If mass is persistent or enlarges, consider further evaluation such as ultrasound or biopsy (avoid fine needle aspiration for neck masses not associated with the thyroid).
• For persistent lymphadenopathy, consider PPD.

IMAGING OPTIONS

• Consider CXR if neck mass is of uncertain etiology.
• Ultrasound is usually the first-line modality to differentiate cystic vs. solid masses, assess vascularity, and guide fine needle aspirations.
• CT with contrast provides anatomic detail for deep lesions but involves radiation exposure.
• MRI offers superior soft-tissue resolution and avoids radiation but often requires sedation.

REFERENCES

https://publications.aap.org/pediatricsinreview/article/34/3/115/34791/Pediatric-Neck-Masses