Skin Cancer – General Characteristics
Skin cancers are malignant growths on the skin. They mostly arise from the upper layer of the skin – epidermis. Skin cancers may develop anywhere on the skin, including scalp, lips, or under-nail skin.
Skin cancers are most common after 50 years of age, but they may occur at any time.
Any chronic skin growth or discoloration that increases in size with time is suspicious for skin cancer.
Skin Cancer Causes and Risk Factors
Common Types of Skin Cancer
There are three common types of skin cancer:
- Basal cell carcinoma
- Squamous cell carcinoma
- Melanoma
Basal Cell Carcinoma
Characteristics:
- Basal cell carcinoma arises from the basal cells in the bottom layer of epiderrmis – stratum basale.
- A pearl-like greyish nodule, few milimmeters in size, appears mostly on the sun exposed areas of the face (including the lips), scalp, neck, upper area of the chest or back, or on the back side of forearms or hands. Several nodules may merge together. A nodule may ulcerate, crust over, or ooze fluid.
- It grows slowly, and rarely spreads to other organs, so it is rarely dangerous.
- Outdoor workers, and those who were exposed to sun for long periods during childhood, are at most risk.
Picture 1. Basal cell carcinoma: a pearl-like tumor with tinny vessels underneath the surface
(source: Samuel Freire da Silva, M.D., atlasdermatologico)
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Picture 2. Basal cell carcinoma under the eye
(source: Samuel Freire da Silva, M.D., atlasdermatologico)
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Additional photos of basal cell carcinoma: Photo 1 , Photo 2 , Photo 3 , Photo 4 , Photo 5 , or visit dermatologic atlas and search for “basal cell carcinoma”.
Treatment
Treatment of basal cell carcinoma is with surgery, radiotherapy, or chemotherapy. Small cancers can be treated with simple excision, or with one of several “small-surgery” techniques like freezing, electrocautering, laser, etc.
Squamous Cell Carcinoma
Characteristics:
- Squamous cell carcinoma arises from squamous cells in the uppermost layer of epidermis – stratum corneum.
- It appears as a scaly, reddish, dome-shaped, fleshy nodule, from 5 mm to few cm (if left untreated) in size, often with central ulcer. It mostly appears on sun exposed areas of the skin or lips.
- It grows slowly, but it can spread to other organs.
Picture 3. Squamous cell carcinoma
(source: Samuel Freire da Silva, M.D., atlasdermatologico)
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Picture 4. Squamous cell carcinoma
(source: Samuel Freire da Silva, M.D., atlasdermatologico)
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Additional photos of squamous cell carcinoma:
Photo 1 , Photo 2 , Photo 3 , Photo 4 , or visit dermatologic atlas and search for “squamous cell carcinoma”.
Treatment
Treatment of squamous cell carcinoma is like in basal cell carcinoma.
Melanoma
Characteristics:
- Melanoma arises from melanocytes (melanin (skin pigment) producing cells) in the epidermis. It may arise from a mole or intact skin.
- A flat or raised growth of black or brown color, often mixed with blue, red, or white parts, from 6 mm to few cm in size, may appear anywhere on the skin, in men mostly on the trunk(Picture 6), in women on the back and legs, and parts of the skin that are usually hidden from the sun, but were exposed to intense sunlight for short periods.
- Melanoma may show one or more of typical ABCDE characteristics: Asymmetry: one part of the tumor differs from other parts; Border of the tumor is irregular; Color: tumor may be of different colors, often several colors are present in one tumor; Diameter above 6 mm (in most cases), Evolving: lesion growths and changes color and appearance with time (Picture).
- It grows slowly or rapidly, and may spread to other organs early (especially nodular type) via lymph vessels and nodes, or via blood, so it can be life dangerous.
Picture 5. Melanoma – partly appearing as nodular growth, and partly as flat nevus
(source: visualsonline.cancer.gov)
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Picture 6. Melanoma on the back
(source: Samuel Freire da Silva, M.D., atlasdermatologico)
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Additional photos of melanoma: Photo 1 ,Photo 2 , Photo 3 , Photo 4 , Photo 5
Melanoma Subtypes
Various subtypes of melanoma have different characteristics (Pictures):
- Superficially spreading melanoma grows relatively slowly.
- Nodular melanoma grows rapidly – weeks to months. It tends to ulcerate and bleed.
- Acral lentiginous melanoma appears in dark skinned people (Afro-American, Asian, and Hispanic), mostly on their palms, soles, and under nails.
- Lentigo maligna melanoma. A macule grows slowly (years) in a patch, over 1-3 cm in size. It doesn’t spread to other organs.
Treatment
Treatment of melanoma is with surgical removal.
Skin Cancer – Treatment Methods
Rare Types of Skin Cancer
The following skin cancers are rare:
- Sebaceus gland carcinoma mostly appears on eyelids in old people. It spreads early, so it is life dangerous. Treatment is with surgical removal. Picture.
- Kaposi’s sarcoma (KS) arises from the cells that line blood or lymph vessels. It is caused by virus HHV-8. Red, purple or brown blotches or nodules appear under different parts of the skin at the same time. KS may be related with organ transplantation, AIDS, Mediterranean heritage, or regions of equatorial Africa. Surgery, chemotherapy, radiotherapy and biologic therapy are available. Prognosis varies a lot from case to case. Picture.
- Anogenital carcinoma includes carcinoma of penis, scrotum, vulva, peri-anal skin, and anus. Multiple wart-like tumors may appear several years after organ transplantation.
- Merkel cell carcinoma arises from neuroendocrine Merkel cells of the skin. It appears as a fleshy red or violet bump on the sun exposed skin. Pictures.
- Cutaneous lymphoma arise from lymphocites in the skin. Several types exist, and they may appear as red patches, plaques or tumors. Picture.
- Dermatofibrosarcoma protuberans is aggressive skin tumor arising from the dermis, and appearing as irregular red to violaceus plaque of various size. Treatment is with surgical removal. Pictures.
- Spindle cell tumors
- Microcystic adnexal carcinoma is a locally aggressive skin tumor arising from sweat glands. It may appear from 10-80 years of age, usually as a yellow or red plaque on the head or neck. Picture.
- Pagets’s disease of the breast is a cancer appearing around the breast nipple, mostly in women, and rarely in men. The skin of the nipple is red and scaly and may itch. In most cases an underlying breast cancer is also present (and felt as a lump). Treatment is with the surgical removal of the breast and lymph nodes in the related armpit. Picture.
- Atypical fibroxanthoma usually appears on the head or neck of the persons whose skin was severely exposed to the sun. Rapidly growing, dome shaped, red nodules may become ulcerated. Treatment is with complete surgical removal, prognosis is good. Picture.
- Leimyosarcoma is a rare tumor arising from smooth muscle cells (that are also present in the skin).
- Angiosarcoma (pictures included) of the skin arises from skin blood vessels. It usually appears on the scalp as a bluish or violaceus nodule or plaque. These are aggressive tumors with poor prognosis. Treatment is with combination of surgery and radiotherapy.
Pre-cancerous Skin Growths
Skin changes that tend to develop into cancer with time are called pre-canceroses. Skin pre-canceroses include:
- Actinic keratosis
- Actinic cheilitis
Non-cancerous Skin Growths
The following skin growths are not cancers and they don’t develop into cancer:
- Warts, including anal and genital warts
- Moluscum contagiousum
- Most of moles (skin tags), but every mole, increasing in size, or changing its appearance is suspicious for skin cancer)
- Most of birthmarks
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