{"id":5869,"date":"2011-10-29T14:26:30","date_gmt":"2011-10-29T13:26:30","guid":{"rendered":"http:\/\/www.ilmelanoma.com\/"},"modified":"2026-10-18T10:14:06","modified_gmt":"2026-10-18T09:14:06","slug":"breslow-index","status":"publish","type":"page","link":"https:\/\/www.ilmelanoma.com\/en\/melanoma\/staging-of-melanoma\/breslow-index\/","title":{"rendered":"Breslow thickness: meaning and melanoma staging"},"content":{"rendered":"<div class=\"im26-diagnosis-guide\">\n<nav class=\"im26-dg-toc\" aria-label=\"On this page\"><strong>On this page<\/strong><\/p>\n<ol>\n<li><a href=\"#guide-section-1\">Thickness, not diameter<\/a><\/li>\n<li><a href=\"#guide-section-2\">How it is measured<\/a><\/li>\n<li><a href=\"#guide-section-3\">Why it matters<\/a><\/li>\n<li><a href=\"#guide-section-4\">Questions about your report<\/a><\/li>\n<li><a href=\"#understanding-the-report\">Understanding Breslow thickness in your report<\/a><\/li>\n<\/ol>\n<\/nav>\n<section id=\"guide-section-1\" class=\"im26-dg-section\">\n<h2>Thickness, not diameter<\/h2>\n<p>Diameter is the visible width of a spot on the skin. Breslow thickness is a vertical microscopic measurement; it cannot be determined from a photograph or measured at home with a ruler.<\/p>\n<\/section>\n<section id=\"guide-section-2\" class=\"im26-dg-section\">\n<h2>How it is measured<\/h2>\n<p>The pathologist measures from the reference surface layer of the epidermis to the deepest invasive tumour cell. With ulceration, measurement starts at the base of the ulcer. An incomplete specimen can limit the measurement, so the report must be interpreted as a whole.<\/p>\n<\/section>\n<section id=\"guide-section-3\" class=\"im26-dg-section\">\n<h2>Why it matters<\/h2>\n<p>Thickness contributes to the melanoma T category and clinical decisions, alongside ulceration and other findings. It does not determine the overall stage by itself. Older \u201clevel\u201d groupings with survival percentages are not an appropriate way to estimate an individual\u2019s risk.<\/p>\n<\/section>\n<section id=\"guide-section-4\" class=\"im26-dg-section\">\n<h2>Questions about your report<\/h2>\n<ul>\n<li>What is the thickness, and is the measurement complete?<\/li>\n<li>Is ulceration present?<\/li>\n<li>What does this mean for my care?<\/li>\n<\/ul>\n<\/section>\n<section id=\"understanding-the-report\" class=\"im26-dg-section\">\n<h2>Understanding Breslow thickness in your report<\/h2>\n<p><strong>Breslow thickness<\/strong>, also called Breslow depth or Breslow index, describes how deeply an invasive melanoma extends into the skin. The result is reported in millimetres after a pathologist examines tissue removed by biopsy or surgery. It is one part of the report, not a diagnosis that can be made from the appearance of a mole.<\/p>\n<h3>Breslow thickness versus Clark level<\/h3>\n<p>Breslow gives a numerical depth; <a href=\"https:\/\/www.ilmelanoma.com\/en\/melanoma\/staging-of-melanoma\/clarks-level\/\">Clark level<\/a> names the anatomical skin layer reached. A result in millimetres cannot be converted directly into a Clark level. Neither measurement alone tells you whether melanoma has reached lymph nodes or distant organs.<\/p>\n<h3>Does a thickness measurement tell me my stage?<\/h3>\n<p>No. In the TNM system, thickness helps describe the primary tumour (T). Ulceration is also relevant, while N and M describe regional and distant spread. Read more about <a href=\"https:\/\/www.ilmelanoma.com\/en\/melanoma\/staging-of-melanoma\/\">melanoma staging and prognosis<\/a> before interpreting a number in isolation.<\/p>\n<h3>A practical way to discuss the result<\/h3>\n<p>For example, \u201cBreslow thickness 0.7 mm\u201d describes a tissue measurement; it is not \u201cstage 0.7\u201d or a personal survival prediction. This is an illustrative example, not a treatment recommendation. Ask whether the report includes ulceration and whether the entire depth could be assessed. Your team uses the complete findings to explain further surgery, possible staging tests and follow-up.<\/p>\n<\/section>\n<aside class=\"im26-dg-related\">\n<h2>Continue reading<\/h2>\n<ul>\n<li><a href=\"https:\/\/www.ilmelanoma.com\/en\/melanoma\/istopatologia-del-melanoma\/\">Histopathology of melanoma<\/a><\/li>\n<li><a href=\"https:\/\/www.ilmelanoma.com\/en\/melanoma\/staging-of-melanoma\/clarks-level\/\">Clark staging system<\/a><\/li>\n<li><a href=\"https:\/\/www.ilmelanoma.com\/en\/melanoma\/staging-of-melanoma\/\">Staging and prognosis<\/a><\/li>\n<\/ul>\n<\/aside>\n<section class=\"im26-dg-sources\">\n<h2>Sources and update<\/h2>\n<ul>\n<li><a href=\"https:\/\/www.cancerresearchuk.org\/about-cancer\/melanoma\/stages-types\/breslow-thickness\" rel=\"noopener\">Cancer Research UK \u2014 Breslow thickness<\/a><\/li>\n<li><a href=\"https:\/\/www.cancer.gov\/types\/skin\/hp\/melanoma-treatment-pdq\" rel=\"noopener\">National Cancer Institute \u2014 Melanoma, health professional PDQ<\/a><\/li>\n<\/ul>\n<p>Editorial update: 18 October 2026. This information provides guidance and does not replace a medical assessment.<\/p>\n<\/section>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>What does Breslow thickness mean? Understand the measurement in millimetres, its role in melanoma staging and how it differs from Clark levels.<\/p>\n","protected":false},"author":13,"featured_media":0,"parent":5660,"menu_order":3,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-5869","page","type-page","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Breslow thickness: meaning and melanoma staging<\/title>\n<meta name=\"description\" content=\"What does Breslow thickness mean? 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