{"id":541,"date":"2021-07-14T18:12:34","date_gmt":"2021-07-14T22:12:34","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/pathology\/?post_type=chapter&#038;p=541"},"modified":"2025-08-19T14:45:52","modified_gmt":"2025-08-19T18:45:52","slug":"pathophysiology-of-melanoma","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/pathology\/chapter\/pathophysiology-of-melanoma\/","title":{"raw":"Pathophysiology of Melanoma","rendered":"Pathophysiology of Melanoma"},"content":{"raw":"<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\r\n<p class=\"textbox__title\">Learning Objectives<\/p>\r\n\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nAt the end of this section, you will be able to:\r\n<ul>\r\n \t<li>Describe how melanoma on the skin would appear upon visual inspection.<\/li>\r\n \t<li>Briefly explain histologically how melanoma originating in the skin can spread via metastasis.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\nMelanoma is a type of cancer arising from damage to the DNA in melanocytes - most commonly in the skin. As such, there is uncontrolled growth (and function) of melanocytes. Initially, the melanocytes, which normally reside near the basement membrane, will grow towards the skin surface ([pb_glossary id=\"2372\"]pagetoid[\/pb_glossary] spread) - thus keeping the basement membrane in tact. To the naked eye, melanoma will look like a dark, irregular looking mole (see later section on early detection), which indicates the increased amount of melanocytes and\/or melanin. However, eventually, the tumour will grow past the basement membrane and invade the dermal layer (papillary layer). Once into the papillary layer of the dermis there are no barriers to moving into the deeper layers of the dermis. The reticular dermal layer contains larger blood and lymphatics vessels - sites where melanoma cells can can enter and spread via metastasis.\r\n\r\nWhen melanoma spreads to distant organs, the cancer, with all of its properties, continue their growth and production of melanin. Signs and symptoms of melanoma will be more recognizable as the growth of the tumour may compress delicate structures (e.g. brain, pulmonary airways and vessels) and\/or the presence of melanin is visibly noticed or found to interfere with the organ's function (e.g. brain, kidney).\r\n\r\n&nbsp;\r\n\r\n[h5p id=\"49\"]\r\n<p style=\"text-align: center;background-color: #f0f0f0;padding: 5px\"><sup>Progression of Melanoma by Lyz Boyd, licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC-BY-NC<\/a><\/sup><\/p>\r\n\r\n<h2>Section Review<\/h2>\r\n<ul>\r\n \t<li>Melanoma appears as an abnormal collection of melanocytes which is visibly noted by a localized darkening of skin (i.e. abnormal mole) of abnormal size, shape, and variety of colours - all of which is indicative of the uncontrolled growth and localized spread of melanocytes.<\/li>\r\n \t<li>If the uncontrolled growth of melanocytes break through the basement membrane of the epidermis, these abnormal melanocytes can be in close proximity to blood and lymphatic vessels that reside in the dermis &amp; hypodermis. Upon entering these vessels, melanoma can spread (metastasize) to distant organs.<\/li>\r\n<\/ul>\r\n<h1>Review Questions<\/h1>\r\n<div class=\"h5p\">[h5p id=\"169\"]<\/div>\r\n<div class=\"h5p\">[h5p id=\"357\"]<\/div>\r\n<div class=\"pdf\">\r\n\r\n<strong>1. Finish the following sentence. Melanocytes normally reside in the:<\/strong>\r\n<ul>\r\n \t<li>Hypodermis<\/li>\r\n \t<li>Dermis<\/li>\r\n \t<li>Stratum corneum<\/li>\r\n \t<li>Basement membrane<\/li>\r\n<\/ul>\r\n<strong>2. Fill in the blanks.<\/strong>\r\n\r\nAs melanocytes develop cancerous change, the rate of melanocyte reproduction increases with melanocytes migrating to the most exposed layer of the skin, the stratum _____. To the naked eye, this could appear as an abnormal skin colouring with moles looking _____ or variable in colour.\r\n\r\n<strong>3. What is the consequence if the rapid growth of melanocytes breaks through the basement membrane? What is below the basement membrane?<\/strong>\r\n\r\n&nbsp;\r\n<div class=\"textbox\">\r\n<h2>Answer Key<\/h2>\r\n<ol>\r\n \t<li>Basement membrane<\/li>\r\n \t<li>Corneum, darker<\/li>\r\n \t<li>Cancerous melanoyctes will break through the basement membrane, entering the dermal layer which has blood vessels and lymphatics. Cancerous melanocytes will enter the lymphatics and thus leave the original site. This is metastasis.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>","rendered":"<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<p class=\"textbox__title\">Learning Objectives<\/p>\n<\/header>\n<div class=\"textbox__content\">\n<p>At the end of this section, you will be able to:<\/p>\n<ul>\n<li>Describe how melanoma on the skin would appear upon visual inspection.<\/li>\n<li>Briefly explain histologically how melanoma originating in the skin can spread via metastasis.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p>Melanoma is a type of cancer arising from damage to the DNA in melanocytes &#8211; most commonly in the skin. As such, there is uncontrolled growth (and function) of melanocytes. Initially, the melanocytes, which normally reside near the basement membrane, will grow towards the skin surface (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_541_2372\">pagetoid<\/a> spread) &#8211; thus keeping the basement membrane in tact. To the naked eye, melanoma will look like a dark, irregular looking mole (see later section on early detection), which indicates the increased amount of melanocytes and\/or melanin. However, eventually, the tumour will grow past the basement membrane and invade the dermal layer (papillary layer). Once into the papillary layer of the dermis there are no barriers to moving into the deeper layers of the dermis. The reticular dermal layer contains larger blood and lymphatics vessels &#8211; sites where melanoma cells can can enter and spread via metastasis.<\/p>\n<p>When melanoma spreads to distant organs, the cancer, with all of its properties, continue their growth and production of melanin. Signs and symptoms of melanoma will be more recognizable as the growth of the tumour may compress delicate structures (e.g. brain, pulmonary airways and vessels) and\/or the presence of melanin is visibly noticed or found to interfere with the organ&#8217;s function (e.g. brain, kidney).<\/p>\n<p>&nbsp;<\/p>\n<div id=\"h5p-49\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-49\" class=\"h5p-iframe\" data-content-id=\"49\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Progression of melanoma\"><\/iframe><\/div>\n<\/div>\n<p style=\"text-align: center;background-color: #f0f0f0;padding: 5px\"><sup>Progression of Melanoma by Lyz Boyd, licensed under <a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC-BY-NC<\/a><\/sup><\/p>\n<h2>Section Review<\/h2>\n<ul>\n<li>Melanoma appears as an abnormal collection of melanocytes which is visibly noted by a localized darkening of skin (i.e. abnormal mole) of abnormal size, shape, and variety of colours &#8211; all of which is indicative of the uncontrolled growth and localized spread of melanocytes.<\/li>\n<li>If the uncontrolled growth of melanocytes break through the basement membrane of the epidermis, these abnormal melanocytes can be in close proximity to blood and lymphatic vessels that reside in the dermis &amp; hypodermis. Upon entering these vessels, melanoma can spread (metastasize) to distant organs.<\/li>\n<\/ul>\n<h1>Review Questions<\/h1>\n<div class=\"h5p\">\n<div id=\"h5p-169\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-169\" class=\"h5p-iframe\" data-content-id=\"169\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Patho of melanoma questions\"><\/iframe><\/div>\n<\/div>\n<\/div>\n<div class=\"h5p\">\n<div id=\"h5p-357\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-357\" class=\"h5p-iframe\" data-content-id=\"357\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Metastatic Melonoma: Pathophysiology\"><\/iframe><\/div>\n<\/div>\n<\/div>\n<div class=\"pdf\">\n<p><strong>1. Finish the following sentence. Melanocytes normally reside in the:<\/strong><\/p>\n<ul>\n<li>Hypodermis<\/li>\n<li>Dermis<\/li>\n<li>Stratum corneum<\/li>\n<li>Basement membrane<\/li>\n<\/ul>\n<p><strong>2. Fill in the blanks.<\/strong><\/p>\n<p>As melanocytes develop cancerous change, the rate of melanocyte reproduction increases with melanocytes migrating to the most exposed layer of the skin, the stratum _____. To the naked eye, this could appear as an abnormal skin colouring with moles looking _____ or variable in colour.<\/p>\n<p><strong>3. What is the consequence if the rapid growth of melanocytes breaks through the basement membrane? What is below the basement membrane?<\/strong><\/p>\n<p>&nbsp;<\/p>\n<div class=\"textbox\">\n<h2>Answer Key<\/h2>\n<ol>\n<li>Basement membrane<\/li>\n<li>Corneum, darker<\/li>\n<li>Cancerous melanoyctes will break through the basement membrane, entering the dermal layer which has blood vessels and lymphatics. Cancerous melanocytes will enter the lymphatics and thus leave the original site. This is metastasis.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_541_2372\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_541_2372\"><div tabindex=\"-1\"><p>\"upward\" direction.  Growth towards the outer, epidermal surface<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":1232,"menu_order":10,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":["lyz-boyd","helen-dyck","jen-2"],"pb_section_license":""},"chapter-type":[],"contributor":[63,59,64],"license":[],"class_list":["post-541","chapter","type-chapter","status-publish","hentry","contributor-helen-dyck","contributor-jen-2","contributor-lyz-boyd"],"part":326,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapters\/541","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/wp\/v2\/users\/1232"}],"version-history":[{"count":26,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapters\/541\/revisions"}],"predecessor-version":[{"id":9343,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapters\/541\/revisions\/9343"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/parts\/326"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapters\/541\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/wp\/v2\/media?parent=541"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/pressbooks\/v2\/chapter-type?post=541"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/wp\/v2\/contributor?post=541"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathology\/wp-json\/wp\/v2\/license?post=541"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}