What is the appropriate workup for a pediatric patient with a cyst on the neck?

Workup for Pediatric Neck Cysts

Ultrasound should be the initial imaging modality for evaluation of a pediatric neck cyst, followed by targeted additional studies based on ultrasound findings and clinical characteristics. 1

Initial Assessment

Clinical Evaluation

• Duration of mass: persistent (>2 weeks) vs recent onset
• Associated symptoms: pain, fever, dysphagia, respiratory symptoms
• Location: midline vs lateral, supraclavicular vs other regions
• Physical characteristics:
  • Size (>1.5-2 cm raises concern)
  • Consistency (firm/hard vs soft)
  • Fixation to adjacent tissues
  • Overlying skin changes (erythema, ulceration)
  • Fluctuation

Red Flags Requiring Urgent Evaluation

• Fixed mass
• Firm/hard consistency
• Size >2 cm
• Ulceration of overlying skin
• Persistent enlargement >2 weeks
• Supraclavicular location
• Absence of inflammatory signs
• Failure to respond to appropriate antibiotics

Imaging Algorithm

1. Ultrasound (First-line imaging) 2, 1

   • Advantages: No radiation, no sedation required, differentiates solid from cystic lesions
   • Can identify congenital abnormalities and discriminate between high-flow and low-flow vascular malformations
   • Helps characterize vascular flow in solid lesions with color Doppler

2. Based on ultrasound findings:

   a. If suggestive of simple congenital cyst (thyroglossal duct cyst, branchial cleft cyst, dermoid cyst):

   • May proceed directly to surgical consultation if diagnosis is clear

   b. If suggestive of malignancy or deep neck infection requiring surgery:

   • CT neck with IV contrast 2, 1

     • Advantages: Shorter examination time, reduced sedation requirements
     • Better for evaluating bony involvement and airway assessment

   • OR MRI neck without and with IV contrast 2, 1

     • Preferred for suspected malignancy requiring detailed soft tissue evaluation
     • No radiation exposure
     • Disadvantage: May require sedation in young children

   c. If vascular malformation is suspected:

   • MRI with contrast for further characterization
   • Time-resolved post-contrast MRA may be useful for evaluating venous malformations 2

Management Based on Suspected Etiology

Congenital Cysts

• Common types: thyroglossal duct cysts, branchial cleft cysts, dermoid cysts 3, 4
• Management: Surgical excision to prevent potential growth and secondary infection 3

Inflammatory/Infectious Cysts

• If clinical features suggest infection:
  • Consider empiric antibiotic therapy targeting S. aureus and Group A Streptococcus 3
  • Reassess within 2 weeks
  • Lack of response should prompt consideration of:
    • IV antibiotics
    • Surgical drainage
    • Further diagnostic workup

Suspected Malignancy

• Cystic neck masses in children should not be assumed benign even if imaging suggests a cystic nature 2
• Referral to pediatric head and neck surgeon for evaluation and possible biopsy if:
  • Concerning features on imaging
  • Persistent enlargement
  • No response to appropriate therapy
  • Supraclavicular location

Special Considerations

• Thyroglossal duct cysts: Typically midline, move with swallowing or tongue protrusion
• Branchial cleft cysts: Usually lateral, anterior to sternocleidomastoid
• Vascular malformations: May change size with Valsalva maneuver or position changes
• Infected cysts: May require aspiration or drainage before definitive treatment

Ancillary Testing (When Indicated)

• Complete blood count if infection or malignancy suspected
• Purified protein derivative test if tuberculosis is a concern
• Serologic testing (EBV, CMV, toxoplasmosis) if clinically indicated 3

Remember that while most pediatric neck cysts are benign, thorough evaluation is essential to rule out malignancy and guide appropriate management.