What are the guidelines for performing a posterolateral neck dissection?

Posterolateral Neck Dissection: Guidelines and Technique

Posterolateral neck dissection is a specialized selective neck dissection that targets the retroauricular, suboccipital, and posterior triangle lymph nodes (levels II-V posteriorly), primarily indicated for malignant epithelial tumors of the posterior scalp and skin posterior to a coronal plane through the ear canals. 1, 2

Primary Indications

• Melanoma and squamous cell carcinoma of the posterior scalp represent the most common indications, with regional disease control achieved in 89-93% of patients 2
• Occult nodal disease (N0) in posterior scalp lesions warrants elective posterolateral dissection, as approximately 38% (5 of 13 patients) demonstrate transformation from cN0 to pN+ disease 3
• Well-differentiated thyroid carcinoma with lateral neck involvement at levels II-V may require posterolateral dissection, though this should be performed only when clinical or radiographic evidence of disease exists 4

Surgical Technique and Anatomic Boundaries

The procedure removes lymph nodes from the retroauricular and suboccipital regions in continuity with the upper posterior triangle and jugular chain, while preserving the spinal accessory nerve, splenius capitis, and sternocleidomastoid muscles. 1

Key Technical Points:

• Levels dissected: Retroauricular, suboccipital, and levels II-V of the posterior triangle 1, 2
• Nerve preservation: The spinal accessory nerve must be preserved to maintain shoulder function 1
• Muscle handling: The sternocleidomastoid can be split longitudinally rather than sacrificed, improving functional outcomes 5
• Bilateral approach: Can be performed bilaterally when indicated for midline or bilateral disease 1

Integration with Standard Neck Dissection Principles

While posterolateral dissection is not explicitly detailed in NCCN guidelines (which focus on anterior and lateral neck levels I-VI), it follows the same staging-based principles:

• For N0 disease: Selective dissection of at-risk nodal basins is appropriate 6, 7
• For N1-N2 disease: Either selective or comprehensive dissection may be performed based on tumor burden 6, 7
• For N3 disease: Comprehensive dissection including all at-risk levels is recommended 6, 7

Expected Outcomes and Morbidity

Regional disease control is achieved in 93% of patients overall (89% for melanoma specifically), with minimal surgical morbidity and excellent functional and cosmetic results. 2

• Local control: 100% in properly selected patients 3
• Regional recurrence: Occurs in only 7% of patients, with most recurrences outside the dissected field 2
• Functional outcomes: Preservation of the spinal accessory nerve maintains shoulder function 1

Critical Pitfalls to Avoid

• Do not perform posterolateral dissection alone for tumors anterior to the ear canal—these require standard lateral neck dissection of levels I-IV 1
• Do not omit elective dissection in posterior scalp melanoma, as occult disease is present in 38% of clinically N0 necks 3
• Do not sacrifice the spinal accessory nerve unless directly invaded by tumor, as preservation maintains quality of life 1
• Ensure adequate lymph node yield: Mean yield should be 18-20 nodes for adequate staging 2, 5

Adjuvant Therapy Considerations

Following posterolateral neck dissection, adjuvant therapy decisions follow standard head and neck cancer principles:

• Extracapsular extension or positive margins mandate postoperative chemoradiation 6
• Multiple positive nodes without extracapsular spread warrant postoperative radiation 6
• High-grade tumors or perineural invasion require adjuvant radiation 6