What is Breslow thickness?

Breslow thickness is the vertical distance from the top of the granular layer of the epidermis (or the base of the ulcer) to the deepest point of tumor invasion, measured in millimeters on histopathologic sections. It is the single most important prognostic factor for primary melanoma.

When is sentinel lymph node biopsy recommended?

Current guidelines (NCCN, SSO) recommend SLNB discussion for T1b melanomas (≥0.8 mm or ulcerated) and routinely recommend it for T2 and above (>1.0 mm). Individual cases may differ based on co-morbidities and clinical context.

How does ulceration affect staging?

Ulceration upgrades the T-sub-stage from "a" to "b" at every thickness category. For example, a 0.6 mm ulcerated melanoma is staged T1b rather than T1a, which has different SLNB and follow-up implications.

How does mitotic rate factor in?

AJCC 8th edition removed mitotic rate from the T1 subcategory criteria. It remains an important prognostic feature to report, but it does not change the T-stage calculated by this tool.

Are the survival estimates from this tool definitive?

No. The estimates reflect population-level AJCC 8th edition survival data and do not account for N or M stage, patient age, anatomic site, or other individual factors. Always refer to a multidisciplinary oncology team for clinical decisions.

What edition of AJCC does this use?

This tool uses the AJCC 8th edition (2017) staging criteria, which is current as of 2025 for most institutions.

Melanoma Breslow Thickness Helper

Enter Breslow thickness and ulceration status to get AJCC 8th edition T-stage, SLNB recommendation, and survival estimates.

Tumor Parameters

Breslow Thickness (mm)

From pathology report, measured in millimeters

Ulceration

Absent Present

Mitotic Rate (mitoses/mm²) — optional

Prognostic context only; not an AJCC 8th edition T-stage criterion

AJCC 8th Ed. T-Stage Reference

StageBreslow / Feature

T1a<0.8 mm, no ulc.

T1b0.8–1.0 mm, or ulc.

T2a>1.0–2.0 mm, no ulc.

T2b>1.0–2.0 mm, ulc.

T3a>2.0–4.0 mm, no ulc.

T3b>2.0–4.0 mm, ulc.

T4a>4.0 mm, no ulc.

T4b>4.0 mm, ulc.

Enter tumor parameters and click Calculate Stage

Results will appear here

Summary

This tool classifies primary cutaneous melanoma by Breslow thickness per the AJCC 8th edition staging system. Enter the pathology-reported depth in millimeters, ulceration status, and mitotic rate to receive the T-stage designation, sentinel lymph node biopsy threshold guidance, and population-level 5-year melanoma-specific survival estimates. For educational and clinical reference only — always confirm staging with a treating oncologist.

How it works

Enter the Breslow thickness in millimeters from the pathology report.
Select whether ulceration is present or absent.
Optionally enter the mitotic rate (mitoses per mm²) if reported.
The tool computes the AJCC 8th edition T-stage (T1a through T4b).
SLNB eligibility threshold and 5-year survival estimates are displayed.

Use cases

Quickly cross-check pathology T-stage from Breslow depth during case review.
Determine whether a patient crosses the SLNB eligibility threshold.
Understand how ulceration upgrades T-stage (e.g., T1a → T1b).
Look up population-level 5-year survival data for patient counseling.
Educate medical students on AJCC melanoma staging criteria.
Compare staging across multiple hypothetical thickness values.

Frequently Asked Questions

Last updated: 2026-06-15 · Reviewed by Nham Vu