What diagnostic tests and imaging are recommended for a lump behind the ear causing jaw and neck pain?

Diagnostic Approach for a Lump Behind the Ear with Jaw and Neck Pain

For a lump behind the ear causing pain in the jaw and down the neck, computed tomography (CT) with contrast or magnetic resonance imaging (MRI) with contrast should be ordered as the primary diagnostic test, followed by fine-needle aspiration (FNA) if the mass appears suspicious for malignancy. 1

Initial Assessment to Determine Risk of Malignancy

When evaluating a post-auricular mass with associated jaw and neck pain, first determine if the patient is at increased risk for malignancy by assessing:

Physical Examination Characteristics

• Fixation to adjacent tissues
• Firm consistency
• Size >1.5 cm
• Ulceration of overlying skin
• Nontender mass (tender masses are less concerning for malignancy)
• Location and extent of the mass 1, 2

History Features

• Duration ≥2 weeks without significant fluctuation
• Absence of infectious etiology
• Uncertain duration of the mass
• Associated symptoms (hearing changes, voice changes, dysphagia) 1

Targeted Physical Examination

• Complete head and neck examination including:
  • Visualization of mucosa of the larynx, base of tongue, and pharynx
  • Otoscopic examination
  • Evaluation of cranial nerve function
  • Assessment of cervical lymph nodes 2

Diagnostic Testing Algorithm

Step 1: Imaging

• First-line imaging: High-resolution CT of the temporal bone without contrast as initial imaging study 2
• For suspected malignancy: Contrast-enhanced neck CT or MRI 1, 2
• For suspected vascular lesion: Consider CT angiography (CTA) 2
• For better soft tissue characterization: MRI with and without contrast if CT findings are inconclusive 2
• For suspected vestibular schwannoma: MRI with gadolinium-enhanced T1-weighted sequences, T2-weighted sequences, and diffusion-weighted imaging 2

Step 2: Tissue Sampling

• Fine-needle aspiration (FNA) should be performed instead of open biopsy for masses deemed at increased risk for malignancy 1, 2
• Continue evaluation of cystic masses until a definitive diagnosis is obtained (do not assume benignity) 1

Step 3: Additional Testing Based on Initial Findings

• If diagnosis remains uncertain after FNA and imaging:
  • Consider additional ancillary tests based on clinical presentation 1
  • Consider examination under anesthesia of the upper aerodigestive tract before open biopsy 1

Important Differential Diagnoses to Consider

The combination of a post-auricular mass with jaw and neck pain raises several important considerations:

1. Metastatic squamous cell carcinoma - most common malignant cause of hard neck masses 3
2. Primary tumors of the external ear - rare but important to identify early 4, 5
3. Referred otalgia from head and neck cancer - pain radiating to ear from primary tumor elsewhere 6
4. Temporomandibular joint (TMJ) syndrome - common cause of referred otalgia with pain radiating to periauricular area, temple, or neck 1
5. Upper aerodigestive tract cancer - may present with otalgia as the only symptom, particularly in older patients with tobacco and alcohol use history or younger patients with HPV infection 1

Common Pitfalls to Avoid

• Do not routinely prescribe antibiotics unless there are clear signs of bacterial infection 1, 2
• Do not assume cystic masses are benign - continue evaluation until a definitive diagnosis is obtained 1, 2
• Do not perform open biopsy before complete evaluation - this can complicate subsequent management 1, 2
• Do not rely on a single imaging modality when diagnosis remains uncertain 2
• Do not overlook the possibility of referred pain - a normal-appearing ear with pain may indicate pathology elsewhere in the head and neck 1, 6

By following this systematic diagnostic approach, you can efficiently evaluate a post-auricular mass with associated jaw and neck pain while minimizing the risk of missing a potentially serious diagnosis.