What is the evaluation and management of a parotid mass?

Evaluation and Management of Parotid Masses

The definitive evaluation and management of a parotid mass requires MRI with and without IV contrast as the initial imaging modality, followed by fine needle aspiration biopsy (FNAB) for tissue diagnosis, and surgical excision as the standard treatment for confirmed malignancies. 1

Initial Diagnostic Approach

Clinical Evaluation

• Symptoms such as pain, facial nerve palsy, and trismus suggest malignancy and should guide the diagnostic workup 1
• Careful examination of the mass and surrounding structures is essential to determine the extent and characteristics of the lesion 1

Imaging Workup

• MRI with and without IV contrast is the preferred initial imaging modality for comprehensive evaluation of parotid masses 1, 2

  • Provides detailed information about mass extent, local invasion, perineural spread, and extension into surrounding structures 1
  • Features suggesting malignancy include T2-hypointensity, intratumoral cystic components, abnormal diffusion coefficient values, and ill-defined margins 2, 1

• Ultrasound is useful for initial assessment to:

  • Distinguish parotid versus extraparotid masses 2
  • Identify features suspicious for malignancy 2
  • Limited in visualizing deep lobe lesions 2, 1

• CT with IV contrast can be used when MRI is contraindicated 1

  • Particularly useful for evaluating bony details and sialoliths 1

Diagnostic Confirmation

• Tissue biopsy is essential to distinguish salivary gland cancers from non-malignant lesions 1
• Fine needle aspiration biopsy (FNAB) is the primary method with high sensitivity (90%) and specificity (95%) 1, 3
• Core needle biopsy may be performed if FNAB is inadequate or for deep minor salivary glands 1
• Pathologists should report risk of malignancy using a risk stratification scheme 1

Treatment Approach

Surgical Management

• Open surgical excision is the standard for histologically confirmed salivary gland malignancies 1
• The extent of surgery depends on tumor characteristics:
  • For low-grade, early-stage tumors: partial superficial parotidectomy may be sufficient 1, 4
  • For high-grade or advanced tumors: at least superficial parotidectomy with consideration of total/subtotal parotidectomy 1

Facial Nerve Management

• Preserve the facial nerve when preoperative function is intact and a dissection plane can be created between tumor and nerve 1
• Resect involved facial nerve branches when:
  • Preoperative facial nerve movement is impaired 1
  • Branches are encased or grossly involved by confirmed malignancy 1

Management of Inflammatory Conditions

• For parotid masses related to inflammatory conditions (e.g., granulomatosis with polyangiitis):
  • Immunosuppressive therapy is the initial treatment of choice 5
  • Glucocorticoids are the primary agent 5
  • Surgical intervention should be reserved for cases requiring urgent decompression 5

Special Considerations

• For recurrent locoregional disease without distant metastases, revision resection with appropriate reconstruction and rehabilitation is recommended 1
• FDG-PET/CT has established value for staging and surveillance of confirmed parotid malignancy but is not recommended as an initial imaging study 1, 2
• For parotitis associated with duct obstruction, MRI sialography may provide complementary assessment of the parotid ducts 2, 5

Common Pitfalls to Avoid

• Relying solely on imaging to determine benign versus malignant nature - histologic confirmation is required 2, 1
• Underestimating deep lobe involvement when using ultrasound alone 2, 1
• Making decisions about facial nerve sacrifice based on indeterminate diagnoses 1
• Failing to consider intraparotid nodal metastases in high-grade or advanced parotid cancers 1
• Initiating surgical intervention before appropriate medical therapy has been attempted for inflammatory conditions 5