Skin cancer
|
Skin cancer Microchapters |
| 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 a 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.[1]
Historical Perspective
Classification
The most common types of skin cancer are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) which may be locally disfiguring but are unlikely to metastasize (spread to other parts of the body). The most dangerous type of skin cancer is malignant melanoma. This form of skin cancer can be fatal if not treated early but comprises only a small proportion of all skin cancers. More rare types of skin cancer include: • Dermatofibrosarcoma protuberans • Merkel cell carcinoma • Kaposi's sarcoma
Pathophysiology
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.[1]
Causes
Differentiating Skin cancer from other Disorders
Epidemiology & Demographics
• Skin cancer is an increasingly common condition. This is in part attributed to increased exposure to ultraviolet radiation, which in turn is thought to be caused by the increased popularity of sun tanning (sun bathing). Lighter-skinned individuals are more vulnerable. In the United States, about one out of every three new cancers arises from the skin.
Risk factors
Skin cancer is most closely associated with chronic inflammation of the skin. This includes: 1. Sunburn or excessive sun damage, especially early in life. UVA & UVB have both been implicated in causing DNA damage resulting in cancer. Sun exposure between 10AM and 4PM is thought to be most harmful. Natural (sun) & artificial UV exposure (tanning salons) are associated with skin cancer. 2. Chronic non-healing wounds, especially burns. These are called Marjolin's ulcers based on their appearance and can develop into squamous cell carcinomaand. 3. Genetic predisposition, including "Congenital Melanocytic Nevi Syndrome". CMNS is characterized by the presence of "nevi" or moles of varying size that either appear at or within 6 months of birth. Nevi larger than 20 mm (3/4") in size are at higher risk for becoming cancerous. Skin can be protected by avoiding sunlight entirely, or wearing protective clothing while outdoors. Skin cancer is usually caused by exposing skin to UV rays excessively. 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.
Screening
Natural History, Complications, and Prognosis
Diagnosis
Staging | History and Symptoms | Physical Examination | Laboratory Tests | Biopsy | Chest X Ray | MRI | CT | Echocardiography or Ultrasound | Other Imaging Findings | Other Diagnostic Studies
Treatment
Medical Therapy | Surgery | Primary Prevention | Secondary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies