In a 65-year-old man with a soft, mobile left parotid mass behind the angle of the jaw and no other symptoms, what is the most likely diagnosis and recommended work‑up?

Parotid Mass in 65-Year-Old Male: Likely Benign Neoplasm Requiring Imaging and FNA

In a 65-year-old man with a soft, mobile left parotid mass and no other symptoms, the most likely diagnosis is a benign salivary gland tumor (particularly pleomorphic adenoma), and you should immediately order contrast-enhanced CT or MRI of the neck followed by fine-needle aspiration (FNA) for tissue diagnosis.

Clinical Assessment and Risk Stratification

The clinical features here suggest lower malignancy risk but do not exclude it:

Reassuring features:

• Soft, mobile consistency
• No facial nerve dysfunction (no facial weakness/paralysis)
• No overlying skin changes
• No associated symptoms (pain, trismus, dysphagia)

However, key considerations:

• Age >60 years increases malignancy risk
• Any parotid mass requires definitive workup regardless of benign features 1
• Clinical examination alone cannot reliably distinguish benign from malignant lesions 2

Immediate Diagnostic Workup

1. Imaging (First-Line)

Order contrast-enhanced CT neck or MRI neck immediately 1:

• CT with IV contrast: Provides excellent anatomic detail, evaluates deep lobe involvement, assesses for bony erosion, and identifies lymphadenopathy 3
• MRI with and without contrast: Superior for soft tissue characterization, perineural spread detection, and defining tumor extent relative to facial nerve 3

MRI is preferred when available as it better delineates the relationship to the facial nerve and detects perineural invasion—critical for surgical planning 3.

2. Tissue Diagnosis

Fine-needle aspiration (FNA) is the standard preoperative diagnostic tool 1:

• Sensitivity 80%, specificity 97% for distinguishing benign from malignant 4
• Critical caveat: FNA has up to 20% false-negative rate 2
• Cannot always determine exact tumor type but guides surgical planning
• Should be ultrasound-guided for accuracy

Do not rely on FNA alone for surgical decision-making—combine with imaging and clinical features 2.

Most Likely Diagnoses (in Order of Probability)

1. Pleomorphic adenoma (most common benign parotid tumor, 60-70% of parotid neoplasms)
2. Warthin tumor (second most common benign, typically in older males, often bilateral)
3. Lipoma (rare but presents as soft, mobile mass) 5, 6
4. Low-grade malignancy (mucoepidermoid carcinoma, acinic cell carcinoma—cannot exclude without tissue diagnosis)

Red Flags That Would Change Management

Watch for features suggesting higher malignancy risk 1, 7:

• Facial nerve weakness or paralysis
• Fixation to adjacent tissues
• Firm or hard consistency
• Size >1.5 cm (this patient likely meets this)
• Rapid growth
• Skin ulceration
• Cervical lymphadenopathy
• Pain or trismus

If any red flags present: Expedite workup and early referral to head and neck surgery.

Surgical Planning Considerations

Once imaging and FNA confirm a neoplasm:

For presumed benign lesions:

• Superficial parotidectomy with facial nerve preservation is standard 2
• Intraoperative frozen section can guide extent of resection 2
• Goal is complete excision with facial nerve preservation

For confirmed or suspected malignancy:

• At minimum superficial parotidectomy, possibly total parotidectomy depending on grade/stage 2
• Facial nerve preserved if not directly invaded 2
• Consider neck dissection for high-grade or advanced tumors

Common Pitfalls to Avoid

1. Assuming soft/mobile = benign: 30% of lipomas present as indurated masses 5; some malignancies can be mobile
2. Delaying imaging: Do not observe and wait—proceed directly to imaging 1
3. Over-relying on FNA: False-negative rate up to 20%; negative FNA does not exclude malignancy if clinical suspicion remains 2
4. Inadequate imaging: Ensure contrast is used unless contraindicated; non-contrast studies miss critical details 3

Timeline for Action

• Imaging: Order within 1-2 weeks
• FNA: Perform after imaging review (within 2-4 weeks of presentation)
• Surgical referral: Once tissue diagnosis obtained, refer to head and neck surgery for definitive management
• Surgery: Typically scheduled within 4-8 weeks of diagnosis for benign lesions; expedited for malignancy

The combination of imaging characteristics (well-circumscribed, homogeneous enhancement) and FNA cytology showing benign features would support observation or elective surgery, while concerning imaging features or indeterminate/malignant cytology mandate prompt surgical intervention 1, 3.