What is the preferred biopsy method, shave biopsy or excisional biopsy, for a patient with a suspected melanoma?

Preferred Biopsy Method for Suspected Melanoma

For suspected melanoma, perform a narrow excisional (complete) biopsy with 1-3 mm margins as the preferred diagnostic approach, which can be accomplished through elliptical excision, punch excision, or deep shave/saucerization technique that extends below the anticipated depth of the lesion. 1

Primary Recommendation: Excisional Biopsy

The American Academy of Dermatology establishes narrow excisional biopsy as the gold standard because it:

• Provides complete tissue sampling of the entire breadth of the lesion 1
• Prevents transection at the base, ensuring accurate Breslow thickness measurement 1, 2
• Allows for proper pathological staging without risk of understaging 1
• Eliminates the need for re-excision in most cases 1

The excisional approach should encompass the entire lesion with 1-3 mm margins and sufficient depth to capture tissue below the anticipated plane of the tumor. 1 This can be achieved through fusiform/elliptical excision, punch excision (when removing the entire lesion), or deep shave/saucerization removal. 1

When Shave Biopsy is Acceptable

Deep shave biopsy (saucerization technique) is acceptable when performed to adequate depth below the lesion, particularly in these scenarios:

• Low clinical suspicion for melanoma 1
• Melanoma in situ, especially lentigo maligna type, where broad shave biopsy optimizes diagnostic sampling 1
• Anatomically challenging locations where complete excision is difficult 1

Critical Distinction: Deep vs Superficial Shave

The depth of shave biopsy is paramount. Superficial shave biopsies should be avoided for suspected invasive melanoma because they underestimate Breslow thickness and clinical stage. 2 However, deep shave biopsies extending into subcutaneous fat are more accurate than punch biopsies for melanomas less than 2 mm thick. 3

Research demonstrates that when performed appropriately by experienced practitioners, shave biopsies are accurate in 97% of cases, with only 3% requiring upstaging after wide excision. 4 Deep shave biopsies showed 88% accuracy in capturing true Breslow depth. 3

When Partial Biopsy is Acceptable

Incisional or partial sampling is acceptable only in highly select circumstances and should be performed by specialists within a skin cancer multidisciplinary team, not in primary care settings: 1, 2, 5

• Facial location (especially lentigo maligna) 1
• Acral locations (palms, soles, subungual) 1
• Very large lesions where complete excision is not initially feasible 1
• Anatomically sensitive areas requiring tissue preservation 1

Critical Pitfalls to Avoid

Do not perform superficial shave biopsies when invasive melanoma is suspected, as they compromise accurate Breslow thickness measurement and lead to understaging. 2

Avoid punch biopsies as the primary diagnostic method for suspected melanoma except in the specific circumstances listed above, because they:

• Have high upstaging rates when residual tumor is found at wide excision 6
• Result in larger mean wide excision areas compared to other biopsy types 6
• Risk missing the thickest portion of the lesion through partial sampling 7
• Prevent accurate pathological staging 7

Research shows that both shave and punch biopsies demonstrate significantly more positive margins (peripheral and deep) compared to excisional biopsy, with higher rates of finding residual tumor at wide excision. 6

Algorithm for Biopsy Selection

Step 1: Assess lesion characteristics and location

• If feasible for complete removal → Perform narrow excisional biopsy with 1-3 mm margins 1, 2
• If complete removal not feasible → Proceed to Step 2 1

Step 2: Determine if special circumstances apply

• Facial lentigo maligna → Broad shave biopsy or incisional biopsy by specialist 1
• Acral location → Incisional biopsy by specialist experienced in nail/acral anatomy 1, 7
• Very large lesion → Incisional biopsy of thickest portion by specialist 1
• Low suspicion → Deep shave biopsy acceptable 1

Step 3: If initial biopsy is inadequate for microstaging

• Perform narrow margin re-excision before proceeding to definitive wide local excision 1, 5
• Do not perform wide excision if initial specimen already meets criteria for sentinel lymph node biopsy consideration 1

Essential Pathology Requirements

Regardless of biopsy technique, ensure the pathologist receives and reports: 1

• Breslow thickness to nearest 0.1 mm 1
• Presence or absence of ulceration 1
• Mitotic rate per mm² 1
• Peripheral and deep margin status 1
• Clark level (optional for Breslow >1 mm) 1

Impact on Clinical Outcomes

Importantly, biopsy type does not impact sentinel lymph node biopsy accuracy (98.5%), tumor recurrence rates, or disease-specific survival when performed appropriately. 6 The finding of residual tumor at wide excision may impact survival on univariate analysis but not on multivariate analysis. 6 Historical data confirms that wide excision as the initial diagnostic procedure does not improve survival compared to other biopsy methods followed by definitive surgery. 8