What is a skin infection?
Your skin is the largest organ of your body. Its function is to protect your body from infection. Sometimes the skin itself becomes infected. Skin infections are caused by a wide variety of germs, and symptoms can vary from mild to serious. Mild infections may be treatable with over-the-counter medications and home remedies, whereas other infections may require medical attention. Read on to learn more about skin infections and what to do if you have one.
What are the types of skin infections?
The following are four different types of skin infections:
1. Bacterial skin infections
Bacterial skin infections often begin as small, red bumps that slowly increase in size. Some bacterial infections are mild and easily treated with topical antibiotics, but other infections require an oral antibiotic. Different types of bacterial skin infections include:
2. Viral skin infections
Viral skin infections are caused by a virus. These infections range from mild to severe. Different types of viral infections include:
shingles (herpes zoster)
hand, foot, and mouth disease
3. Fungal skin infections
These types of skin infections are caused by a fungus and are most likely to develop in damp areas of the body, such as the feet or armpit. Some fungal infections aren’t contagious, and these infections are typically non-life-threatening.
Different types of fungal infections:
4. Parasitic skin infection
These types of skin infections are caused by a parasite. These infections can spread beyond the skin to the bloodstream and organs. A parasitic infection isn’t life-threatening but can be uncomfortable.
Different types of parasitic skin infections include:
cutaneous larva migrans
Pictures of types of skin infections
What are the symptoms of skin infection?
The symptoms of a skin infection also vary depending on the type. Common symptoms include redness of the skin and a rash. You may also experience other symptoms, such as itching, pain, and tenderness.
See a doctor if you have pus-filled blisters or a skin infection that doesn’t improve or gets progressively worse. Skin infections can spread beyond the skin and into the bloodstream. When this happens it can become life-threatening.
Signs of a severe infection include:
skin sloughing, breakdown
dark, necrotic-appearing skin, or skin that becomes discolored and painful
What are causes and risk factors for a skin infection?
The cause of a skin infection depends on the type of infection.
Bacterial skin infection: This occurs when bacteria enter the body through a break in the skin, such as a cut or a scratch. Getting a cut or scratch doesn’t necessarily mean you’ll develop a skin infection, but it does increase your risk if you have a weakened immune system.
A decreased immune system can be the result of an illness or the side effect of medication.
Viral skin infection: The most common viruses come from one of three groups of viruses: poxvirus, human papillomavirus, and herpes virus.
Fungal infection: Body chemistry and lifestyle can increase the risk of a fungal infection. For example, you may experience multiple bouts of athlete’s foot if you’re a runner or if you sweat a lot. Fungi often grow in warm, moist environments. Wearing sweaty or wet clothes is a risk factor for skin infections. A break or cut in the skin may allow bacteria to get into the deeper layers of the skin.
Parasitic skin infection: Tiny insects or organisms burrowing underneath your skin and laying eggs can cause a parasitic skin infection.
Skin cancer is the most common type of cancer diagnosed in the United States and can be broken down into squamous cell cancers, basal cell cancers, and melanomas, as well as some less common cancers. Symptoms may include a sore that doesn't heal, a new spot on the skin, or a mole that is changing. When doctors suspect skin cancer during an exam, a biopsy is needed to make the diagnosis. Treatment options depend on the type and stage, with surgery to remove cancer being the most common approach. With melanomas and advanced squamous cell carcinomas, other treatments such as immunotherapy, chemotherapy, or radiation may be needed. Luckily, there are many simple things you can do to lower your risk.
At the current time, skin cancer is considered an epidemic in the United States, accounting for 50 percent of all cancers. Roughly 80 percent of skin cancer-related deaths are due to melanoma.
Many people do not think of the skin as an organ, but like other organs, it has a discrete structure and many important functions. Since treatment options for skin cancer often depend on the depth of cancer, it's helpful to understand the three basic layers of the skin.
The epidermis is the top layer of skin and serves several functions, including protecting the interior of your body from the environment. Cells in this layer include the following, which give rise to the most common skin cancers—squamous cell carcinoma, basal cell carcinoma, and melanoma:
Squamous cells lie just below the outer surface of the skin.
Basal cells lie beneath the squamous layer and produce new skin cells.
Melanocytes are located in the basal cell layer of the skin and produce melanin, the pigment that gives skin its color.
The dermis is the middle layer of skin made up of collagen and elastin. It contains hair follicles, oil-producing glands (sebaceous glands), nerves, and blood vessels.
The subcutaneous tissue contains fat, connective tissue, and larger blood vessels; the amount of this tissue varies depending on a person's weight.
There are three common types of skin cancer and more than 100 less common types. Together, basal cell carcinoma, and squamous cell carcinoma are referred to as non-melanoma skin cancers.
Basal Cell Carcinoma
Basal cell carcinoma (BCC) is the most common form of skin cancer, accounting for 75 percent to 80 percent of these cancers. The lifetime risk of developing a basal cell carcinoma is around 30 percent. It was once found mostly in middle-aged or older people, but is increasingly being found in younger people. It is the most common skin cancer among Hispanics.
Basal cell carcinoma usually begins on areas exposed to the sun, such as the face, neck, and hands. It is slow-growing cancer that rarely spreads to other parts of the body, but people with a history of BCC are at higher risk for getting a second case.
Cancer originates in the basal cell layer of the epidermis (the stratum basale). The basal cells there mutate and begin to replicate uncontrollably. As the cancerous cells grow, they can spread into the dermis, nearby lymph nodes, and may eventually invade bones. If not treated, they can damage the surrounding tissue, causing disfigurement.
Treatments are very effective when these cancers are found and treated promptly.
Squamous Cell Carcinoma
Squamous cell carcinoma (SCC) accounts for 16 percent to 20 percent of skin cancers and occurs twice as often in men as in women. These are the most common type of skin cancers found in blacks.
Unlike basal cell carcinomas, these cancers may spread (metastasize) if they become large. It usually occurs on the face, ear, neck, lips, and backs of the hands. SCC can also begin within scars or skin ulcers on other places on the body. As with basal cell carcinoma, the available treatments are very effective if the tumor is detected while it is small and thin.
Squamous cell carcinomas have the strongest association with sun exposure.
Melanoma is the most feared type of skin cancer. Though less common than basal cell and squamous cell cancer, it is responsible for the majority of deaths from the disease as a whole. Melanoma may arise in normal skin but often begins in an existing mole. It is found most frequently on the back in men, on the legs in women, and on the palms of the hands, soles of the feet, and under the fingernails or toenails of people of both sexes with darker skin colors. That said, these cancers may occur anywhere, including areas of the skin that have never been exposed to the sun.
The incidence of melanoma has been rising dramatically in the United States for the last three decades. While melanoma in general is 20 times more common in whites, the incidence of cases that occur under the nails is similar for people of all skin color. In addition, the survival rate in those diagnosed is lower in blacks.
The prognosis of melanoma is good when found early, but drops precipitously when it spreads to distant lymph nodes or organs, such as the bones, the lungs, the liver, and the brain. Newer treatments, however, are making a difference in survival, and even some advanced melanomas can now be controlled with these options.
The other types of cancer that can arise in the skin or skin-related structures are far less common. A few of these include:
Merkel cell carcinoma: Merkel cell carcinomas are rare skin cancers most often found around the eye in middle-aged people. For unknown reasons, these cancers are increasing. They tend to be aggressive and spread rapidly to other parts of the body.
Kaposi's sarcoma: This cancer is caused by the Kaposi sarcoma herpesvirus, and is usually found in people with HIV/AIDS or who are immunosuppressed for other reasons, such as an organ transplant. It presents as large red, blue, or brown splotches around the body along with swelling that can be severe. Fortunately, it often responds well to HIV medications.
Sebaceous gland carcinoma: These cancers originate in sebaceous glands and occur most often in older women, around the eye.
Dermatofibrosarcoma protuberance: These cancers begin as a hard nodule that originates in the dermis and spreads rapidly. They are related to a gene mutation that results in overproduction of a protein known as a platelet-derived growth factor.
Skin Metastases and Other Cancers That Occur in the Skin
Sometimes, cancers that arise in other areas of the body may spread (metastasize) to the skin. Cancers most commonly associated with skin metastases include breast cancer, colon cancer, and lung cancer. When other cancers spread to the skin they are not classified as skin cancer. In fact, though cancer may now be affecting the skin, its cells are clearly identifiable as belonging to instigating cancer when examined under a microscope. Treatment for cancer at play, rather than skin cancer, is needed.
Some examples of this include inflammatory breast cancer, which often begins with redness and a rash on the breast); Paget's disease, a form of breast cancer that begins on the skin of the nipples; and cutaneous T cell lymphomas (including mycosis fungoides and Sezary syndrome), which often begin as flat, red patches of skin that are extremely itchy.
Signs and symptoms of skin cancer may include any change that is noted on the skin, such as:
A sore that doesn't heal
A mole that is changing
Scaly, crusty appearing lesions
Pink, white, or flesh-colored lumps that appear dome-like
Some refer to the ABCDE (and F) mnemonic to help them recognize when a skin change could be skin cancer:
A stands for asymmetry: A mole or sore that is asymmetric.
B stands for borders. The borders of a melanoma may be irregular, notched, or blurry.
C stands for color. Melanomas often have more than one color or hue.
D stands for diameter. A mole that is larger than a pencil eraser is more likely to be a melanoma.
E stands for either elevation or evolution. The mole may be elevated (often irregularly) and is often evolving (changing) over time.
F: Though an unofficial qualifier, many add this to represent a skin change that is "funny" looking.
What Are the Most Common Skin Cancer Symptoms?
Causes and Risk Factors
We don't know exactly what causes skin cancer, though we have identified several risk factors. Some of these include:
Sun exposure (especially extensive and/or unprotected)
Red or blonde hair
Light eyes (green or blue eyes)
Skin that rarely tans and burns easily
Family and/or personal history of skin cancer
Having one of several genetic syndromes, such as xeroderma pigmentosum
Having many moles (more than 50) or having atypical moles (nevi)
Scars from burns or previous skin infections
A weakened immune system
Use of some medical treatments and medications, such as radiation therapy for cancer and ultraviolet light for psoriasis
Frequent exposure to chemicals such as tar and vinyl chloride
Exposure to arsenic in drinking water
Smoking (increases the risk of squamous cell carcinoma)
Causes and Risk Factors of Skin Cancer
Diagnosing skin cancer begins with a careful history (paying attention to symptoms and risk factors) and a physical exam. Based on the appearance of the skin lesion, a doctor may recommend a biopsy, as it can sometimes be difficult to know whether an abnormality is cancer or not based on its visible appearance. This can be even more challenging in non-white populations.
A biopsy can be done in one of several ways, including:
Shave biopsy: The most common if a basal cell or squamous cell carcinoma is suspected), this procedure involves numbing the skin and shaving off a piece of the lesion. A punch biopsy may also be done.
Incisional biopsy: An incision is made and part of an abnormality is removed to be viewed by a pathologist.
Excisional biopsy: In this case, the entire abnormality is removed, along with an area of surrounding tissue, for a pathologist's evaluation. This is done if a melanoma is suspected.
If a skin cancer (melanoma and sometimes squamous cell carcinoma) is advanced, further tests are done to stage the disease and search for the presence of metastases. These may include a sentinel node biopsy, CT scans, a PET scan, or other tests depending on the location of the skin cancer.
How Skin Cancer Is Diagnosed
The treatments for skin cancer will depend on many factors, such as the type of cancer, the size and depth, and more.
Surgically removing the tumor is the most common treatment. A special surgery called Mohs surgery involves removing successive pieces of tissue and checking the margins for any evidence of cancer so that the least amount of surgery to completely remove the tumor is done. With melanomas, a large area of surrounding tissue is removed.
For more advanced tumors that have spread to lymph nodes or other regions of the body, treatments such as immunotherapy, chemotherapy, targeted therapy, and radiation therapy may be needed.
What Are Your Skin Cancer Treatment Options?
Prevention and Early Detection
There are many things you can do to prevent skin cancer or at least reduce your risk. Being careful in the sun is important, but includes more than just wearing sunscreen; using other methods of protection (such as wearing clothing and hats, and avoiding mid-day sun) should be practiced as well. Some occupational exposures may increase risk, and gloves are recommended when working with many different chemicals and substances.
Not all skin cancers can be prevented, and early detection then becomes the goal. Self-skin checks should be considered, especially for those who have any risk factors for the disease. Some people who have significant risk factors or genetic syndromes associated with a higher risk may want to consider regular visits with their dermatologist.
Seborrheic keratosis (seb-o-REE-ik ker-uh-TOE-sis) is one of the most common noncancerous skin growths in older adults.
A seborrheic keratosis usually appears as a brown, black or light tan growth on the face, chest, shoulders or back. The growth has a waxy, scaly, slightly elevated appearance. Seborrheic keratoses don't become cancerous and aren't thought to be related to sun exposure, but they can look like skin cancer.
Seborrheic keratoses are normally painless and require no treatment. You may decide to have them removed if they become irritated by clothing or for cosmetic reasons.
A seborrheic keratosis usually looks like a waxy or wart-like growth. It typically appears on the face, chest, shoulders or back of the body. You may develop a single growth or cluster of them. A seborrheic keratosis:
Varies in color, usually from light tan to brown or black
Is round or oval-shaped
Has a characteristic "pasted on" look
Is flat or slightly elevated with a scaly surface
Ranges in size from very small to more than 1 inch (2.5 centimeters) across
Seborrheic keratoses aren't usually painful, but they can be bothersome depending on their size and location. Be careful not to rub, scratch or pick at them. This can lead to bleeding, swelling and, in rare cases, infection.
When to see a doctor
See your doctor if:
Many growths develop over a short time.
The growths get irritated or bleed when your clothing rubs against them. You may want the growths removed.
You notice suspicious changes in your skin, such as sores or growths that grow rapidly, bleed and don't heal. These could be signs of skin cancer.
The exact cause of seborrheic keratoses isn't known. They are very common and generally increase in number with age. The lesions aren't contagious. They tend to run in some families, so inheritance may play a role.
You can develop seborrheic keratoses at any age, but you're generally more likely to develop them if you're over age 50. You're also more likely to have them if you have a family history of the condition.