NMSC, also know as “white skin cancer”, has its origin in the epidermis and occurs mainly in older people. A distinction is made between different variants, the most common being basal cell carcinoma and squamous cell carcinoma, both of which are mainly caused by UV-radiation from the sun. However, they can also be preceded by other skin conditions such as actinic keratosis.
Long wave UV-A radiation penetrates deeper in the skin and reaches the lower layer of the epidermis. The DNA of the basal cells that are arranged in this layer get damaged by the radiation. If the natural repairing mechanism does not avoid the propagation of damaged cells, tumor cells develop, which can reproduce uncontrollably.
In addition to exposure by intensive UV-A radiation, a basalioma can develop from benign alterations of the skin (e.g. liver spots, angiomas, keratodermas) or from scars. Additionally some genetic diseases such as xeroderma pigmentosum and Gorlin Goltz syndrome, or arsenic intoxication pose individuals at high risk for developing basal cell carcinoma.
Basal cell carcinoma, at 75-80% of skin cancers found, is the most frequent form of non-melanoma skin cancer. However, metastases arise extremely rarely. About 80% of these tumours appear on the head, face or neck (these areas are considered sun terraces). In only 5% of cases, patients have affected arms and legs.
Generally, the growth of these tumors is rather slow. Yet, basaliomas can grow into lower tissue layers, such as bones.
Both genders are affected equally. The highest frequency of these tumors is found in individuals between ages 65-69 years.
Basal cell carcinomas can be distinguished into 3 different types, according their characteristics.
Nodular cell carcinoma
Solid basaliomas are formed from skin accentuated nodes. The surface of these nodes may appear white and shiny, with small blood vessels often visible. Additionally, it is possible that these lesions become ulcerated, which eventually burst and bleed. With nodular basaliomas, the affected tissue is well delimited from surrounding healthy tissue.
Infiltrative Basal Cell Carcinoma
These basaliomas can be easily confused with scars. Small blood vessels may be visible within these tumors. Different from nodular cell carcinomas, it is difficult to identify the delimitation from the surrounding healthy tissue. This is because these lesions may expand several centimeters into the surrounding healthy tissue. However, this expansion is not visible to the naked eye.
Nodular basal cell carcinomas can also grow deeply into the skin, eroding it (loss of skin tissue). This erosion (“gnawing”) of the skin is commonly known as Ulcus Rodens.
These large lesions often develop from nodes which go untreated. This results in lesions which grow deeply into the skin and eventually scar.
These lesions develop when short-wave UV-B radiation does not penetrate deeply in the skin, but rather, damages the outer cell layer of the epidermis, the squamous epithelium.
Squamous cell carcinomas can develop from scars or long-lasting inflamed wounds. In the buccal cavity (inner mouth region), toxins from alcohol and tobacco often contribute to the development of these lesions.
In addition to UV-B radiation exposure, individuals with weak immune systems (e.g. AIDS) or those experiencing immunosuppression (e.g. organ transplantation) are at risk for this type of non-melanoma skin cancer. “Moon child” disease (Xeroderma pigmentosa) is a possible genetic cause for developing squamous cell carcinoma.
- Squamous cell carcinoma is the second most common malignant skin cancer, making up 22% of all skin cancer cases.
- Metastasis can be spread through blood or lymph vessels; however, this is seen in only about 5% of cases.
- 80% of these tumors appear in the “sun terraces” (bald head, face, nose bridge, cheeks, ears, neck).
- Men are more frequently affected than women.
- Men between 70 and 74 years and women between 75 and 79 years of age are most frequently affected by SCC.
Two different skin disorders may precede mature squamous cell carcinoma formation: Actinic Keratosis and Bowen’s Disease.
In Actinic Keratosis, only a reddish and scaly spot is seen. The growth of the tumor begins with this spot and expands gradually into the surrounding tissue.
These tumors easily damage and bleed. Therefore, blood scabs often appear and cover the lesions.
Doctors can easily recognize these tumors. However, further studies must be completed to define the expansion of the tumor. Some possible tests to determine lesion characteristics include lymphatic drainage area studies and lymph node sonography. Eventually, X-ray, CT and MRI studies may be done.
The word melanoma comes from the Greek word for “black,” signifying that these tumors develop from melanocytes. Melanocytes are skin cells which contain the pigment melanin, responsible for the browning of our skin when exposed to sunlight. In medicine, the term “malignant” is used for tumors which are highly lethal, damaging surrounding healthy tissue and capable of producing secondary growths (metastases).
Severe sunburns, with pronounced redness, pain and vesicle formation, are a risk factor for developing malignant melanomas. Children who experience these burns are strongly at risk for these tumors later in life. Those with fair skin and light hair color (blond or red hair) are particularly vulnerable. Skin with freckles and moles is particularly vulnerable to sun damage.
Nevi (single = nevus), also known as birthmarks or moles, are benign cells that are closely related to melanocytes. These cell clusters appear either round or oval, with clearly formed borders. They are often uniformly brown in color.
It is important to recognize malignant melanomas as early as possible, when there are higher chances for recovery. Good chances of recovery exist for lesions which are flat or thin, and for those without infiltration into deeper skin layers (>97% recovery during initial stages).
Detecting Suspicious Moles
To determine how “suspicious” a mole may be, doctors use the “ABCDE-Rule” to describe malignant tumors
A = Asymmetry
The shape of the skin alteration is asymmetrical or uneven.
B = Border
The skin alteration has no sharp or clearly defined borders, but instead uneven, scalloped edges.
C = Color
The skin alteration has an uneven pigmentation, with different colors like brown, black, white, grey and red or parts which are lighter or darker.
D = Diameter
The skin alteration has increased in size.
E = Evolving
The skin alteration is raised or lowered from the surrounding skin.