What is the best course of action for a suspected inclusion cyst in the neck?

Management of a Suspected Inclusion Cyst in the Neck

For a suspected inclusion cyst in the neck, clinicians should perform fine-needle aspiration (FNA) instead of immediate open biopsy, after appropriate imaging with contrast-enhanced CT or MRI, and should not assume the mass is benign until a definitive diagnosis is obtained. 1

Initial Assessment and Risk Stratification

When evaluating a suspected inclusion cyst in the neck, first determine if the patient is at increased risk for malignancy based on:

History factors indicating increased risk:

• Mass present for ≥2 weeks without fluctuation
• Mass of uncertain duration
• No clear infectious etiology 1

Physical examination findings indicating increased risk:

• Fixation to adjacent tissues
• Firm consistency
• Size >1.5 cm
• Ulceration of overlying skin 1

Diagnostic Algorithm

1. Imaging (Strong Recommendation)

   • Order contrast-enhanced neck CT or MRI 1
   • Ultrasound may be used as initial imaging for superficial masses or to guide FNA 1
   • Imaging helps characterize the lesion and identify concerning features such as:
     • Large size
     • Central necrosis with rim enhancement
     • Multiple enlarged lymph nodes
     • Extracapsular spread
     • Asymmetric wall thickness
     • Nodularity
     • Non-conforming cystic wall 1

2. Fine-Needle Aspiration (Strong Recommendation)

   • Perform FNA instead of immediate open biopsy 1
   • May need to be repeated or image-guided if initial results are inconclusive
   • Target any solid components or the cyst wall 1

3. Further Evaluation for Cystic Masses

   • Critical caveat: Do not assume a cystic neck mass is benign 1
   • Up to 62% of neck metastases from Waldeyer ring sites (tonsils, nasopharynx, base of tongue) are cystic
   • 10% of malignant cystic neck masses present without an obvious primary tumor
   • The incidence of cancer in cystic neck masses increases to 80% in patients >40 years old 1, 2

4. Additional Steps if Diagnosis Remains Uncertain

   • Consider ancillary tests based on clinical suspicion 1
   • For suspected malignancy without a clear diagnosis after FNA and imaging, recommend examination of the upper aerodigestive tract under anesthesia before open biopsy 1

Management Based on Diagnosis

• Confirmed benign inclusion cyst: Complete surgical excision is typically recommended to prevent recurrence, infection, or continued growth 3
• Inconclusive diagnosis: Continue evaluation until definitive diagnosis is obtained 1
• Malignancy suspected: Refer to head and neck cancer specialist for comprehensive management 1

Important Considerations

• Sensitivity of FNA is lower in cystic cervical metastases (73%) versus solid masses (90%) 1
• Malignant cystic neck lesions in adults can mimic benign cysts (e.g., branchial cleft cysts) on imaging and FNA 1, 4
• If malignancy is suspected and repeated FNA yields inadequate or benign results, expedient open excisional biopsy is recommended 1
• Excisional biopsy is preferred for cystic masses to reduce the risk of tumor spillage 1

Special Populations

• Adults >40 years of age with cystic neck masses require particularly thorough evaluation due to high risk of malignancy 1, 2
• With increasing incidence of HPV-positive oropharyngeal cancers, vigilance for malignancy is warranted across all adult age groups 1

Remember that inclusion cysts can grow slowly over many years without symptoms, but proper diagnosis is essential to rule out malignancy, especially in adults 3.