What is the diagnosis and management for a young male with a painful lateral neck swelling that moves with swallowing and has increased in size, with potential diagnoses including hemorrhage into a thyroid cyst, infected branchial cyst, or infected thyroglossal cyst?

Diagnosis: Infected Thyroglossal Cyst

The most likely diagnosis is an infected thyroglossal cyst, given the midline location (moves with swallowing), young male patient, painful presentation, and recent size increase. 1, 2

Clinical Reasoning

Key Diagnostic Features

The clinical presentation points strongly toward thyroglossal cyst pathology:

• Movement with swallowing is the pathognomonic feature of thyroglossal duct cysts, as they are attached to the hyoid bone and thyroid cartilage 1
• Lateral neck location makes branchial cleft cyst possible, but the swallowing movement argues against this diagnosis 3, 2
• Pain and rapid size increase suggest either infection or hemorrhage into a pre-existing cyst 1, 4

Why Not the Other Diagnoses?

Infected branchial cyst is less likely because:

• Branchial cleft cysts are typically lateral neck masses that do not move with swallowing 2, 5
• They occur along the anterior border of the sternocleidomastoid muscle 3
• The question states "lateral" but also "moves with swallowing" - this combination favors thyroglossal pathology

Hemorrhage into thyroid cyst is possible but:

• Hemorrhagic thyroid cysts typically present with sudden, severe pain and rapid progression over hours, not gradual increase 4
• They often cause airway compromise quickly 4
• The clinical course described (painful, increased size) is more consistent with infection than hemorrhage 3

Immediate Diagnostic Workup

Imaging Priority

Obtain contrast-enhanced CT or MRI immediately for any neck mass in adults at risk for malignancy 3, 1:

• CT with contrast is the first-line imaging modality for suspected infected cysts, as it identifies abscesses and inflammatory changes 3, 2
• MRI provides superior soft tissue characterization if malignancy needs to be excluded 1, 2
• Imaging characteristics suggesting infection include: enhanced wall thickening, perilesional inflammation, and debris within the cyst 3, 2

Critical Malignancy Considerations

Do not assume any midline cystic mass is benign without thorough evaluation 1:

• Thyroglossal duct carcinoma, though rare, occurs in adults 1
• Cystic metastases from papillary thyroid carcinoma can mimic benign cysts 5
• In adults over 40 years, up to 80% of cystic neck masses are malignant 3, 2

Tissue Diagnosis

Fine needle aspiration (FNA) should be performed as first-line histologic assessment 1, 2:

• FNA has moderate sensitivity (62%) for thyroglossal duct cyst diagnosis 6
• Cytomorphologic features include colloid (thick/fragmented or watery), macrophages, lymphocytes, and ciliated columnar epithelium 6
• If FNA is non-diagnostic or malignancy is suspected, repeat FNA with image guidance or proceed to excisional biopsy 3, 2

Management Algorithm

If Infection Confirmed

1. Initiate broad-spectrum antibiotics covering oral flora and skin organisms 2
2. Consider aspiration if abscess is present on imaging 2
3. Definitive surgical excision (Sistrunk procedure) should be performed after infection resolves 1

If Airway Compromise Develops

Immediate intervention is required if signs of airway obstruction appear 3:

• Administer supplemental oxygen and position patient head-up 3
• Call for senior surgical and anesthetic support immediately 3
• Consider IV dexamethasone and tranexamic acid 3
• Prepare for emergency intubation or surgical airway 3

Common Pitfalls to Avoid

• Do not dismiss lateral neck masses in young adults as benign without imaging and tissue diagnosis - cystic metastases from occult thyroid carcinoma can present this way 5
• Do not rely solely on clinical examination - imaging is essential to characterize the mass and rule out malignancy 3, 1
• Do not delay diagnosis - timely evaluation directly affects tumor stage and prognosis if malignancy is present 3, 5
• Do not assume FNA is definitive - sensitivity is only 62% for thyroglossal duct cysts, and repeat sampling may be needed 6