A form of cancer that begins in melanocytes (cells that make the pigment melanin). It may begin in a mole (skin melanoma), but can also begin in other pigmented tissues, such as in the eye or in the intestines.


The outer layer of the two main layers of the skin. Most epidermal skin is composed of 4 sub-layers, but thicker skin like that of the palms and soles are composed of 5 sub-layers. The outermost skin in the epidermis is called the cornified layer (stratum corneum).


The inner layer of the two main layers of the skin which has connective tissue, blood vessels, oil and sweat glands, nerves, hair follicles, and other structures. It is made up of a thin upper layer called the papillary dermis, and a thick lower layer called the reticular dermis.

UV Radiation

A non-visible form of radiation emitted by the sun and absorbed by the ozone layer of our atmosphere. UV radiation damages DNA chain links in melanocytes, causing uncontrolled cell proliferation (cancer).

Sentinel Lymph Node Biopsy

A sentinel lymph node biopsy is prompted by a melanoma Breslow Thickness of at least 1mm. This procedure is used to determine lymph node involvement, an important part of the melanoma staging process. Sentinel lymph node biopsies are performed by injecting lymphazurin (Isosulfan blue) dye and radioactive sulfur colloid into the primary melanoma. Using a gamma sensor probe, doctors can determine to which lymph node the sulfur colloid travelled, and pinpoint its exact location by observing which node is stained blue. This node is most likely to contain metastatic disease, and is therefore dissected and biopsied. The result of the sentinel lymph node biopsy is used for pathological staging which informs proper course of treatment.

Radial Growth

The early pattern of growth of cutaneous malignant melanoma in which tumor cells spread laterally along the epidermis. This is observable growth, as the lesion grows across the skin, instead of growing deeper into the skin.

Vertical Growth

The late pattern of growth of cutaneous malignant melanoma in which tumor cells penetrate and spread to deeper skin tissues.

Papillary (Superficial) Dermis

The thin top layer of the dermis (the inner layer of the skin). The papillary dermis has connective tissue and blood vessels that give nutrients to the epidermis (the outer layer of the skin) and that help control the temperature of the skin. Source

Reticular Dermis

The thick bottom layer of the dermis (the inner layer of the skin). The reticular dermis has blood vessels and connective tissue that supports the skin. Hair follicles, oil and sweat glands, and other structures are also found in the reticular dermis. Source

Subcutaneous Fat

 at that is stored directly under the skin. Women have a higher percentage of this fat than men. Source