How to approach a patient with neck swelling and a single nodule with a differential diagnosis of hemorrhagic cyst and how frequently to repeat ultrasound of the neck?

Approach to Neck Swelling with TIRADS 1 Nodule and Hemorrhagic Cyst Differential

For patients with a neck swelling and a TIRADS 1 nodule with a differential diagnosis of hemorrhagic cyst, clinicians should continue evaluation until a definitive diagnosis is obtained and should not assume the mass is benign, with follow-up ultrasound recommended at 6-12 month intervals initially. 1

Initial Diagnostic Approach

• Fine needle aspiration (FNA) should be used as the first-line modality for histologic assessment for any adult with a cystic neck mass, as it is minimally invasive and provides valuable diagnostic information 1
• Ultrasound-guided FNA is recommended over conventional FNA, especially for cystic masses, as it increases specimen adequacy by facilitating directed biopsy of solid components 1
• If initial FNA results are inadequate or indeterminate, repeat FNA should be attempted before resorting to an open biopsy 1
• On-site evaluation by a cytopathologist, when available, can reduce the inadequacy rate of FNA and improve diagnostic yield 1

Risk Assessment for Malignancy

• Clinicians should be aware that cystic neck masses in adults over 40 years have up to 80% risk of malignancy, compared to 4-24% overall incidence of malignancy in cystic neck masses 1
• Imaging characteristics suggestive of malignancy in cystic masses include large size, central necrosis with rim enhancement, multiple enlarged lymph nodes, extracapsular spread, asymmetric wall thickness, nodularity, and nonconforming cystic wall 1
• A single cervical cystic lymph node metastasis can mimic a branchial cleft cyst clinically, radiologically, and even histologically if not examined thoroughly 1
• Malignant cystic neck lesions are often difficult to differentiate from benign cysts on imaging due to similar appearance 1

Imaging Recommendations

• Neck computed tomography (CT) with contrast or magnetic resonance imaging (MRI) should be ordered for patients with a neck mass deemed at increased risk for malignancy 1
• Ultrasound is valuable for characterizing cystic masses and should be performed prior to needle aspiration or open excisional biopsy 2
• Ultrasound can help differentiate simple cysts from complex cysts, with hemorrhagic cysts typically showing internal echoes and irregular borders 3
• For TIRADS 1 nodules specifically, which are considered benign, follow-up ultrasound is still recommended to monitor for changes 1

Follow-up Recommendations

• For TIRADS 1 nodules with hemorrhagic features:
  • Initial follow-up ultrasound at 6-12 months 1
  • If stable after initial follow-up, subsequent ultrasounds every 12-24 months for at least 5 years 1
  • Any significant change in size, appearance, or symptoms should prompt immediate re-evaluation 1

Special Considerations for Hemorrhagic Cysts

• Hemorrhagic cysts typically show internal echoes and irregular borders on ultrasound, which can make them difficult to distinguish from malignant lesions 3
• Serial ultrasounds are typically recommended for hemorrhagic cysts when malignancy is unlikely 3
• If there are concerning features or changes over time, further evaluation with CT or MRI may be necessary to distinguish hemorrhagic cysts from malignant tumors 3

When to Consider More Invasive Diagnostic Procedures

• If repeated FNA or image-guided FNA are inadequate or benign but malignancy is still suspected, an expedient open excisional biopsy is recommended 1
• Core needle biopsy may be considered after an initial inadequate or indeterminate FNA, with ultrasound guidance showing high rates of adequacy (95%) and accuracy (94-96%) 1
• Excisional biopsy is preferred for cystic masses to reduce the risk of tumor spillage into the wound if malignancy is present 1

Pitfalls to Avoid

• Do not assume that a cystic neck mass is benign, even if initial evaluation suggests a benign etiology 1
• The sensitivity of FNA is lower in cystic cervical metastases (73%) versus solid masses (90%), which may lead to false-negative results 1
• Papillary thyroid carcinoma, lymphoma, and oropharyngeal carcinoma can all present as cystic neck masses that mimic benign lesions 1
• With increasing incidence of HPV-positive oropharyngeal head and neck squamous cell carcinoma, the proportion of cystic neck masses that are malignant continues to rise 1