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 the 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 a 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

Skin Cancer Pictures

The pictures below are of the three most common skin cancers. It is important to note that other skin lesions like warts, solar purpura and fungal infections such as tinea nigra, can have a similar presentation. Therefore the skin lesion needs to be investigated by a dermatologist to confirm whether it is a cancer or not. As a general rule, always suspect that a suspicious looking lesion is cancer until proven otherwise.

Basal Cell Carcinoma

Characteristics:

  • Basal cell carcinoma arises from the basal cells in the bottom layer of the 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 the sun for long periods during childhood are at most risk.

Skin cancer - basal cell carcinomaPicture 1. Basal cell carcinoma: a pearl-like tumor with the tinny vessels underneath the surface
(source: Samuel Freire da Silva, M.D., atlasdermatologico)

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Basal cell carcinomaPicture 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 check in a dermatologic atlas (search for ‘basal cell carcinoma’).

Treatment

Treatment of basal cell carcinoma is by a surgery, radiotherapy or chemotherapy. Small cancers can be treated with simple excision or with one of several “small-surgery” techniques, like freezing, electrocautering or laser.

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 a 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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Skin cancer - squamous cell carcinoma on the facePicture 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 check in a dermatologic atlas (search for ‘squamous cell carcinoma’).

Treatment

Treatment of squamous cell carcinoma is like in basal cell carcinoma.

Melanoma

Characteristics:

  • Melanoma arises from melanocytes (skin pigment melanin 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.

Skin cancer: melanomaPicture 5. Melanoma – partly appearing as a nodular growth, and partly as a flat nevus
(source: visualsonline.cancer.gov)

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Skin cancer: melanoma on the backPicture 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) as a patch, over 1-3 cm in size. It does not spread to other organs.

Treatment

Treatment of melanoma is by surgical removal.
Skin Cancer – Treatment Methods

Rare Types of Skin Cancer

The following skin cancers are rare:

  • Sebaceus gland carcinoma mostly appears on the eyelids in old people. It spreads early, so it is life dangerous. Treatment is by surgery. Picture of sebaceus gland carcinoma.
  • Kaposi’s sarcoma (KS) arises from the cells that line the blood or lymph vessels. It is caused by a 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 of Kaposi’s sarcoma.
  • 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 of Merkel cell carcinoma.
  • Cutaneous lymphomaarises from lymphocites in the skin. Several types exist, and they may appear as red patches, plaques or tumors. Picture of cutaneus lymphoma.
  • Dermatofibrosarcoma protuberansis an aggressive skin tumor arising from the dermis, and appearing as irregular red to violaceus plaque of various size. Treatment is with surgical removal. Pictures of dermatofibrosarcoma.
  • Spindle cell tumors
  • Microcystic adnexal carcinoma is a locally aggressive skin tumor arising from the sweat glands. It may appear in people from 10 to 80 years of age, usually as a yellow or red plaque on the head or neck. Picture of microcystic adnexal carcinoma.
  • 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 by surgical removal of the breast and lymph nodes in the related armpit. Picture of Paget’s disease of the breast.
  • Atypical fibroxanthoma usually appears on the head or neck in people whose skin was severely exposed to the sun. Rapidly growing, dome shaped, red nodules may become ulcerated. Treatment is by complete surgical removal, prognosis is good. Picture of atypical fibroxanthoma.
  • 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 the 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 a cancer with time are called pre-canceroses. Skin pre-canceroses include:

Non-cancerous Skin Growths

The following skin growths are not cancers and they do not 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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Article reviewed by Dr. Greg. Last updated on August 3, 2013