Should I biopsy a suspicious skin lesion if I'm unsure about it?

Should You Biopsy a Suspicious Skin Lesion If You're Unsure?

Yes, you should biopsy any suspicious skin lesion when you are uncertain about the diagnosis—clinical uncertainty is itself an indication for tissue sampling to establish a definitive diagnosis and guide appropriate treatment. 1, 2

When Clinical Suspicion Warrants Biopsy

The threshold for biopsy should be low when malignancy cannot be confidently excluded clinically. The fundamental principle is that tissue diagnosis is required when:

• The lesion has any features concerning for melanoma or other skin cancer 1, 2
• Clinical examination alone cannot definitively establish a benign diagnosis 1
• The lesion is changing, symptomatic, or atypical in appearance 2

For suspected melanoma specifically, any diagnostic uncertainty mandates biopsy rather than observation, as delayed diagnosis directly impacts mortality and requires more extensive surgery. 1, 2

Choosing the Correct Biopsy Technique

For Suspected Melanoma

Perform a narrow excisional/complete biopsy with 1-3 mm margins as the gold standard approach. 1, 2 This can be accomplished through:

• Fusiform/elliptical excision 1
• Deep shave/saucerization extending below the anticipated plane of the lesion 1
• Punch excision (only if it can encompass the entire lesion) 1

The biopsy must extend to sufficient depth—into the deep papillary or superficial reticular dermis—to prevent transection at the base and ensure accurate Breslow thickness measurement. 1

When Partial Biopsy Is Acceptable

Incisional or punch biopsy may be used only in highly specific circumstances: 1, 2

• Facial location (especially lentigo maligna) 1, 2
• Acral sites (palms, soles, nail apparatus) 1
• Very large lesions where complete excision is not initially feasible 1, 2
• Low clinical suspicion with diagnostic uncertainty 1

Critical caveat: Partial biopsies should only be performed by specialists within a skin cancer multidisciplinary team, never in primary care settings. 3, 2 If a punch biopsy is performed, it must be full-thickness and target the clinically thickest portion of the lesion. 3

For Suspected Non-Melanoma Skin Lesions

For dermatofibrosarcoma protuberans or other deep dermal/subcutaneous lesions, punch or incisional biopsy must include the deeper subcutaneous layer for accurate diagnosis. 1 Superficial sampling frequently leads to misdiagnosis. 1

If initial biopsy is indeterminate or clinical suspicion persists despite benign pathology, rebiopsy is mandatory. 1

Critical Pitfalls to Avoid

Superficial Sampling

Never perform superficial shave biopsies for suspected invasive melanoma—they systematically underestimate Breslow thickness and clinical stage, leading to inadequate treatment. 1, 2 The exception is broad shave biopsy for suspected melanoma in situ (lentigo maligna type), which should extend into deep papillary or superficial reticular dermis. 1

Delayed Diagnosis

Do not observe suspicious lesions with short-interval follow-up when biopsy is indicated. 1 For melanoma, observation delays diagnosis and worsens prognosis. Clinical uncertainty itself justifies immediate tissue sampling rather than watchful waiting.

Inadequate Tissue Sampling

If the initial biopsy is inadequate for diagnosis or microstaging, perform rebiopsy with narrow margin excision before proceeding to definitive wide excision. 3 This two-step approach ensures accurate pathological staging and appropriate treatment planning based on correct Breslow thickness. 3

Geographic Correlation

Always ensure the biopsy samples the clinically suspicious area. 1 For dermatofibrosarcoma protuberans specifically, this tumor is frequently misdiagnosed due to inadequate tissue sampling, as the superficial aspect may not be distinct from benign lesions. 1

Practical Algorithm for Decision-Making

1. Assess clinical suspicion: Any features concerning for melanoma (asymmetry, border irregularity, color variation, diameter >6mm, evolution) or other malignancy warrant biopsy 1, 2

2. Choose biopsy technique based on lesion characteristics:

   • Preferred: Narrow excisional biopsy with 1-3mm margins for suspected melanoma 1, 2
   • Alternative: Incisional/punch biopsy only for facial, acral, or very large lesions, performed by specialist 1, 3, 2
   • Deep lesions: Ensure sampling includes subcutaneous layer 1

3. If pathology is discordant with clinical suspicion: Rebiopsy or proceed to excision 1, 3

4. If initial biopsy inadequate for staging: Perform narrow margin excision before definitive wide excision 3

The overarching principle: When in doubt, biopsy. The risks of delayed diagnosis for melanoma and other skin cancers far outweigh the minimal risks of the biopsy procedure itself. Clinical uncertainty is not a reason to observe—it is an indication for tissue diagnosis. 1, 2