Skin cancer

Skin cancer Microchapters
Patient Information
Overview
Historical Perspective
Classification Melanoma Basal cell carcinoma Squamous cell carcinoma of the skin Actinic keratosis Bowen's disease Keratoacanthoma Dermatofibrosarcoma protuberans Merkel cell carcinoma Kaposi's sarcoma Angiosarcoma Cutaneous B cell lymphoma Cutaneous T-cell lymphoma Sebaceous gland carcinoma
Pathophysiology
Causes
Epidemiology & Demographics
Risk factors
Screening
Diagnosis
Treatment
Prevention

Skin cancer
ICD-10	C43-C44
ICD-9	172, 173
ICD-O:	8010-8720
MeSH	D012878

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Sara Mohsin, M.D.[2]Faizan Sheraz, M.D. [3]

Overview

Skin cancer is the malignant growth on the skin which can have many causes. Skin cancer generally develops in the epidermis (the outermost layer of skin), so a tumor is usually clearly visible. This makes most skin cancers detectable in the early stages. There are three common types of skin cancer, each of which is named after the type of skin cell from which it arises. Cancers caused by UV exposure may be prevented by avoiding exposure to sunlight or other UV sources, wearing sun-protective clothes, and using a broad-spectrum sun screen. Skin cancers are the fastest growing type of cancer in the United States. Skin cancer represents the most commonly diagnosed malignancy, surpassing lung, breast, colorectal and prostate cancer. More than 1 million Americans will be diagnosed with skin cancer in 2007.

Historical Perspective

• The 1992-1994 free AAD programs disseminated broad skin cancer educational messages, enabled thousands to obtain a free expert skin cancer examination, and found mostly thin, localized stage 1 melanomas (usually associated with a high projected 5-year survival rate). Because biases impose possible limitations, future studies with long-term follow-up and formal control groups should determine the impact of early detection programs on melanoma mortality.
• American Academy of Dermatology National Melanoma/Skin Cancer Screening Program experience 2001-2005.A higher-risk subgroup of the skin cancer screening population can be identified through assessment of MM risk factors using the HARMM criteria. Refocusing efforts to provide a total skin examination to those individuals with multiple risk factors has the potential to both reduce costs and increase yields for suspected MM in future mass screening initiatives.

Classification

• Skin cancer is broadly divided into melanoma and nonmelanoma types as shown in the following table:

Classification of skin cancer

Skin cancer type	Characteristics
Malignant melanoma	Can occur anywhere in the body involving either even normal skin or any existing mole becoming cancerous later on Signs suspicious for melanoma include: Mole changing in size, color, feel or bleeding Large brownish spot having darker speckles Itchy or burning painful lesion Darker lesions involving fingertips, toes, palms, soles, or mucous membrane lining of nose, mouth, anus or vagina Small lesion having irregular borders & portions with multiple colors such as white, pink, red, blue or blue-black Most dangerous type of skin cancer Fatal if not treated early Comprises only a small portion of all skin cancers	Most common type
Nonmelanoma skin cancers
Basal cell carcinoma (BCC)	Mostly occurs on the sun-exposed areas such as: Face Neck May appear as any of the following: Waxy or a pearly bump Brown scar-like or flesh-colored flat lesion Scabbing or a bleeding sore (heals and returns)	Most common types
Squamous cell carcinoma (SCC)	Mostly involves sun-exposed skin areas such as: Face Ears Hands Unexposed areas to sun are also involved in darker-skinned individuals May appear as any of the following: Red, firm nodule Flat lesion having a crusted, scaly surface Local disfiguration Unlikely to metastasize
Dermatofibrosarcoma protuberans		Rare types
Merkel cell carcinoma	Most commonly involves: Head Neck Trunk Appear as shiny, firm nodules just beneath or on the skin & in hair follicles
Kaposi's sarcoma	Involves the blood vessels of skin Forms purple or red patches on skin or mucous membrane Involves individuals: Having weak immune system such as: AIDS patients Patients on immunosuppressant therapy (after an organ transplant) Young African men Eastern European jewish or Italian older men
Angiosarcoma
Cutaneous B-cell lymphoma
Cutaneous T-cell lymphoma
Sebaceous gland carcinoma	Uncommon Aggressive tumor of sebaceous glands Can occur anywhere but most commonly involves eyelids

Pathophysiology

• Skin cancer is most closely associated with chronic inflammation of the skin
• UVA & UVB have both been implicated in causing DNA damage resulting in cancer
• Macroscopically, the tumor is often elevated, fungating, or may be ulcerated with irregular borders
• Microscopically, tumor cells destroy the basement membraneand form sheets or compact masses which invade the subjacent connective tissue (dermis)
• In well differentiated carcinomas, tumor cells are pleomorphic/atypical, but resembling normal keratinocytes from prickle layer (large, polygonal, with abundant eosinophilic (pink) cytoplasm and central nucleus)
• Their disposal tends to be similar to that of normal epidermis: immature/basal cells at the periphery, becoming more mature to the centre of the tumor masses
• Tumor cells transform into keratinized squamous cells and form round nodules with concentric, laminated layers, called "cell nests" or "epithelial/keratinous pearls"
• The surrounding stroma is reduced and contains inflammatory infiltrate (lymphocytes)
• Poorly differentiated squamous carcinomas contain more pleomorphic cells and no keratinization

Epidemiology & Demographics

• Skin cancer is a common condition because of the increased exposure to UV radiation (caused by increasing popularity of sun tanning/sun bathing)
• Individuals with lighter-skin are more vulnerable to get it
• One out of every three new cancers arises from skin in United States

Risk factors

Common risk factors for skin cancer include:

Risk factors for the development of skin cancer

Risk factors	Associated features
Excessive sun exposure	Sun bathing Especially early in life can lead to skin damage and even sunburn if skin isn't protected by: Clothing Sunscreen Sun exposure between 10AM and 4PM is considered to be most harmful
Artificial UV exposure	Tanning is the response of skin to excessive UV radiations: Tanning salons Tanning lamps Tanning beds
Fair skin	Less melanin pigment in the skin means less protection from damaging UV radiation
Genetic predisposition	Congenital Melanocytic Nevi Syndrome is characterized by: Presence of varying sized "nevi" or moles Appear at or within 6 months of birth Nevi larger than 20 mm (3/4") in size are at higher risk for becoming cancerous
Chronic non-healing wounds	Especially burns, known as Marjolin's ulcers (can transform into squamous cell carcinoma)
Prior history of sunburns	History of one or more of the blistering sunburns during childhood or teenage years increases the risk of skin cancer as an adult Sunburns in adult life
High altitude or sunny climate	Increased sunlight exposure occurs to the people living in the areas having: High altitude (i.e. closer to the sun) Warm, and sunny climate (as compared to a colder climate)
Prior chemotherapy	Previous history of chemotherapy puts a person at an increased risk for developing a skin cancer
Moles	Having large number of moles increases the chances of having skin cancer in future Dysplastic nevi which are multiple abnormal irregular moles, have increased tendency to become cancerous
Advanced age	Age >70 years
Precancerous skin lesions	Actinic keratoses increases the risk of having skin cancer and has the following characteristics: Dark pink to brown, scaly, rough patches Involves head, face, and hands Fair-skinned individuals are most commonly affected as their skin is more prone to sun damage
Radiation exposure	There's an increased risk for development of skin cancer (especially basal cell carcinoma) in individuals with a prior history of radiation therapy for skin conditions such as: Acne Eczema
Personal history of skin cancer	Individuals who have developed skin cancer once are at increased risk for developing it again anytime later in their lives
Exposure to certain substances	Arsenic
Family history of skin cancer	Individuals having a family history of skin cancer especially in parents and siblings are at elevated risk of developing skin cancer themselves
Weakened immune system	Due to: HIV infection (AIDS) Taking immunosuppressant therapy after organ transplantation
Male gender	Being a male is also one of the risk factors for developing skin cancer as compared to the female population

Screening

• The Melanoma Genetics Program, which works to identify the genetic causes of skin cancer, and which provides genetic counseling for those with a strong family history of melanoma.
• The 1992-1994 free AAD programs disseminated broad skin cancer educational messages, enabled thousands to obtain a free expert skin cancer examination, and found mostly thin, localized stage 1 melanomas (usually associated with a high projected 5-year survival rate). Because biases impose possible limitations, future studies with long-term follow-up and formal control groups should determine the impact of early detection programs on melanoma mortality.
• American Academy of Dermatology National Melanoma/Skin Cancer Screening Program experience 2001-2005.A higher-risk subgroup of the skin cancer screening population can be identified through assessment of MM risk factors using the HARMM criteria. Refocusing efforts to provide a total skin examination to those individuals with multiple risk factors has the potential to both reduce costs and increase yields for suspected MM in future mass screening initiatives.
• The use of dermoscopy improves the ability of PCPs to triage lesions suggestive of skin cancer without increasing the number of unnecessary expert consultations.
• In a primary care setting the combination of dermoscopy and short-term sequential digital dermoscopy imaging (SDDI) reduces the excision or referral of benign pigmented lesions by more than half while nearly doubling the sensitivity for the diagnosis of melanoma

Diagnosis

History and Symptoms

Common sites of involvement

• Primarily involves the sun-exposed areas of skin such as:
  • Scalp
  • Face
  • Lips
  • Ears
  • Neck
  • Chest
  • Arms
  • Hands
  • Legs (especially in women)
  • Eyelids (sebaceous gland carcinoma)
• Can also involve the skin areas very rarely exposed to sun such as:
  • Underneath fingernails or toenails
  • Palm of the hand
  • Sole of the foot
  • Genital region

Common symptoms

• There are a variety of different skin cancer symptoms
• These include crabs or changes in the skin that do not heal, ulcers in the skin, discoloration, and changes in existing moles.

Physical Examination

• Basal cell carcinoma usually looks like a raised, smooth, pearly bump on the sun-exposed skin of the head, neck or shoulders
• Sometimes small blood vesselscan be seen within the tumor
• Crusting and bleeding in the center of the tumor frequently develops
• It is often mistaken for a sore that does not heal
• Squamous cell carcinoma is commonly a red, scaling, thickened patch on sun-exposed skin
• Ulceration and bleeding may occur
• When SCC is not treated, it may develop into a large mass
• Most melanomas are brown to black looking lesions
• Signs that might indicate a malignant melanoma include change in size, shape, color or elevation of a mole
• The appearance of a new mole during adulthood, or new pain, itching, ulceration or bleeding of an existing mole should be checked

Treatment

• For low-risk disease, radiation therapy, electrotherapy, and cryotherapy (freezing the cancer off) can provide adequate control of the disease; both, however, have lower overall cure rates than surgery
• Moh's Microsurgery is a technique used to remove the cancer with the least amount of surrounding tissue and the edges are checked immediately to see if tumor is found
• This provides the opportunity to remove the least amount of tissue and provide the best cosmetically favorable results
• This is especially important for areas where excess skin is limited, such as the face
• Cure rates are equivalent to wide excision
• Special training is required to perform this technique
• In the case of disease that has spread (metastasized) further surgical or chemotherapy may be required

Prevention

Although the possibility of skin cancer can't be eliminated completely, but the risk for developing skin cancer can be significantly reduced by acting on the following preventive measures in the first place to decrease the excessive exposure to UV rays:

Primary preventive measures for skin cancer

Preventive method	Details
Avoiding sunburns and suntans	Avoid sun exposure: During the middle of the day, usually from 10 AM to 4 PM, especially in North America Even during cloudy days or winters
Wearing protective clothing	Wear the following while being in the outdoor environment: Tightly woven, dark clothing Shirts with long sleeves Broad-brimmed hats Pants that fully cover the legs (avoid shorts) Photoprotective clothing Sunglasses (the ones which block both types of UV radiation i.e. UVA & UVB)
Wearing SPF sunscreen	Wear a sunscreen generously year-round, even during winters & cloudy days It should be at least SPF 30 It should be broad-spectrum blocking both UVA and UVB rays Cover all the exposed areas including the back of hands, neck, lips, tip of ears Reapply it every 2 hours & more often after swimming or if perspiring a lot
Avoiding tanning beds	Tanning beds use the lights that emit UV rays which can increase the risk for skin cancer
Being aware of sun-sensitizing medications	Over-the-counter drugs and common prescriptions including antibiotics may have tendency to increase the sensitivity of skin Always ask the doctor or pharmacist about the possible side effects of any medications before taking them Take extra precautions to protect the skin by staying away from the sun,in case if the medications being used have tendency to increase the skin sensitivity to sunlight
Checking skin regularly and reporting any new or unusual skin changes to the doctor	Examine the skin often for any new skin growths or changes in existing moles, bumps, birthmarks, & freckles Check face, ears, neck, and scalp by using the mirror Examine the chest, trunk, top & underside of arms and hands Examine both the front and back of legs, and feet, including soles and spaces between the toes Also check the genital area and area between the buttocks
Watching dysplastic nevi (abnormal irregular multiple moles) regularly	Watch dysplastic nevi (abnormal irregular multiple moles) regularly as they have increased tendency to become malignant
Reducing the exposure to ultraviolet (UV) radiation, especially during the early years of life	Prior history of radiation exposure (both UV or artifical radiation therapy for acne or eczema) leads to increased chance for development of basal cell carcinoma

Related Chapters

• Cancer
• Mohs surgery

References

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