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Breslow & Clark Microstaging

Breslow Thickness: The primary factor determining T-stage and surgical margins.

Melanoma Type

Stage 0 - Confined to epidermis

Breslow Depth (mm)

Ulceration

Stage Derivation

Enter the Breslow thickness and ulceration status to derive the AJCC T-category and recommended excision margins.

Guidelines & Evidence

Verified

Last Review: 2026

When to Use

Breslow thickness and Clark level are the two primary histopathological measurements obtained from melanoma biopsy specimens. Breslow thickness is the dominant prognostic variable in all modern staging systems and directly determines surgical margins and sentinel lymph node biopsy (SLNB) eligibility. Clark level is a secondary anatomical descriptor that retains limited utility in specific circumstances.

Indications

All confirmed primary cutaneous melanoma biopsy specimens — mandatory measurement

Determining T-category in AJCC 8th edition melanoma staging

Guiding excision margin width (thickness-based)

Determining eligibility and urgency for sentinel lymph node biopsy

Prognostic counseling following pathological diagnosis

When NOT to Use

Shave biopsies that transect the base — Breslow thickness will be artificially underestimated; re-excision biopsy required

Melanoma in situ (Tis) — no Breslow depth applicable; excision with 0.5–1 cm margins

Clark level alone for AJCC staging — replaced by Breslow thickness in 8th edition

Uveal or mucosal melanoma — different staging systems apply

Related Scores in Practice

In clinical practice, this assessment is frequently evaluated alongside other validated measures. Depending on the patient's presentation and specific diagnostic requirements, you may also need to utilize the AJCC Melanoma Staging, Seven Point Dermoscopy, Melanoma Risk Screening or the MSK Melanoma Nomogram to formulate a comprehensive care plan.

Last Comprehensive Review: 2026