What are the recommended evaluation and diagnostic tests for a lump behind the ear?

Evaluation and Diagnostic Tests for a Lump Behind the Ear

For a lump behind the ear, clinicians should perform a targeted physical examination to identify risk factors for malignancy, followed by high-resolution CT of the temporal bone without contrast as the initial imaging modality, and fine-needle aspiration (FNA) if malignancy is suspected. 1, 2

Initial Assessment

Physical Examination

The physical examination should focus on identifying characteristics that increase risk for malignancy:

• Suspicious physical characteristics 1:

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

• Additional concerning features 1:

  • Nontender mass (tender masses are more likely inflammatory)
  • Duration ≥2 weeks without fluctuation
  • Absence of infectious etiology
  • Associated symptoms (hearing loss, voice changes, dysphagia)

Targeted Examination

A comprehensive examination should include 1:

• Complete head and neck examination
• Visualization of mucosa of the larynx, base of tongue, and pharynx
• Otoscopic examination to identify any retrotympanic lesions
• Evaluation of cranial nerve function
• Assessment of cervical lymph nodes (noting size, location, mobility)

Diagnostic Testing Algorithm

First-Line Imaging

High-resolution CT of the temporal bone without contrast is recommended as the initial imaging study 2:

• Provides excellent delineation of bony structures, air spaces, and soft tissue
• Helps identify inflammatory or neoplastic masses
• Shows potential erosion of ossicles or other structures
• Assists with surgical planning

Additional Imaging Based on Clinical Suspicion

1. If vascular lesion is suspected (pulsatile tinnitus or red retrotympanic mass) 2, 3:

   • CT angiography (CTA) should be considered
   • Can identify vascular variants or pathology like paragangliomas or vascular anomalies

2. If soft tissue characterization is needed 2:

   • MRI with and without contrast
   • Superior for soft tissue contrast
   • Helps differentiate between inflammatory changes, cholesteatoma, and tumors

3. For patients at high risk of malignancy 1:

   • Contrast-enhanced neck CT or MRI is strongly recommended
   • Evaluates extent of disease and potential nodal involvement

Tissue Sampling

Fine-needle aspiration (FNA) is strongly recommended over open biopsy for patients with neck masses at increased risk for malignancy 1:

• Less invasive
• Lower risk of complications
• Can provide definitive diagnosis in many cases

For cystic masses, continued evaluation is necessary until a diagnosis is obtained, as these may still represent malignancy 1.

Special Considerations

For Suspected Vestibular Schwannoma

If symptoms suggest vestibular schwannoma (hearing loss, tinnitus) 1:

• MRI with gadolinium-enhanced T1-weighted sequences
• Include T2-weighted sequences and diffusion-weighted imaging
• Thin slice imaging through internal auditory canal

For Pediatric Patients

Consider syndromic associations that may present with post-auricular masses 1:

• Renal ultrasound may be indicated
• Audiologic evaluation
• Referral to genetics if multiple anomalies are present

Common Pitfalls to Avoid

1. Inappropriate antibiotic use - Antibiotics should not be routinely prescribed unless there are clear signs of bacterial infection 1

2. Inadequate imaging technique - Standard head CT provides insufficient detail; ensure thin-section imaging is performed 2

3. Assuming cystic masses are benign - Continue evaluation of cystic masses until a definitive diagnosis is obtained 1

4. Performing open biopsy before complete evaluation - For patients at high risk of malignancy, examination under anesthesia of the upper aerodigestive tract should be performed before open biopsy if diagnosis remains uncertain after FNA and imaging 1

5. Relying on a single imaging modality - Consider both CT and MRI when diagnosis remains uncertain 2