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
- Skin cancer is broadly divided into melanoma and nonmelanoma types as shown in the following table:[1]
| Skin cancer type | Characteristics | |
|---|---|---|
| Malignant melanoma | Most common type | |
| Nonmelanoma skin cancers | ||
| Basal cell carcinoma (BCC) | Most common types | |
| Squamous cell carcinoma (SCC) |
| |
| Dermatofibrosarcoma protuberans | Rare types | |
| Merkel cell carcinoma | ||
| Kaposi's sarcoma | ||
| Angiosarcoma | ||
| Cutaneous B-cell lymphoma | ||
| Cutaneous T-cell lymphoma | ||
| Sebaceous gland carcinoma | ||
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.
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. [2]
Risk factors
Common risk factors for skin cancer include:[3]
| Risk factors | Associated features |
|---|---|
| Excessive sun exposure |
|
| Artificial UV exposure | |
| Fair skin |
|
| Genetic predisposition | |
| Chronic non-healing wounds |
|
| Prior history of sunburns | |
| High altitude or sunny climate | |
| Prior chemotherapy | |
| Moles | |
| Advanced age | |
| Precancerous skin lesions | |
| Radiation exposure |
|
| Personal history of skin cancer | |
| Exposure to certain substances | |
| Family history of skin cancer | |
| Weakened immune system | Due to:
|
| Male gender |
Screening
Natural History, Complications, and Prognosis
Diagnosis
History and 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. The following image is an example of how skin cancer can affect the nails. Image shown below is courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology
Laboratory Tests
Biopsy
Other Diagnostic Studies
Treatment
For low-risk disease, radiation therapy 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.[1]
Prevention
Although it is impossible to completely eliminate the possibility of skin cancer, the risk of developing such a cancer can be reduced significantly with the following steps: • Reducing exposure to ultraviolet (UV) radiation, especially in early years • Avoiding sunburns • Avoiding sun exposure during the day (usually from 10 AM to 3 PM), when the sun is highest in the sky • Wearing protective clothing (long sleeves and hats) when outdoors • Using a broad-spectrum sunscreen that blocks both UVA and UVB radiation • Use SPF sun block of at least 50 • Reapply sun block every 2 hours and after swimming Although it is generally accepted that UV exposure is the greatest risk factor in melanoma development, some skeptics say that there is no proven data that links moderate sun exposure with the appearance of melanoma.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.
Related Chapters
References
- ↑ "Nonmelanoma skin cancer - Symptoms and causes - Mayo Clinic".
- ↑ "Common Cancer Types - National Cancer Institute".
- ↑ Ishdorj G, Beiggi S, Nugent Z, Streu E, Banerji V, Dhaliwal D; et al. (2019). "Risk factors for skin cancer and solid tumors in newly diagnosed patients with chronic lymphocytic leukemia and the impact of skin surveillance on survival". Leuk Lymphoma: 1–10. doi:10.1080/10428194.2019.1620941. PMID 31237469.