Psoriasis is a skin disorder that causes areas of scaly or thickened skin. While it can occur anywhere on the body, certain types of psoriasis, such as plaque psoriasis, are more likely to affect the back of the knees.
More than 3% of adults in the United States live with psoriasis. This skin disorder occurs when new skin cells grow faster than the body can shed old cells.
There are multiple types of psoriasis, each presenting uniquely in various parts of the body. Psoriasis behind the knees, for example, can be a common experience for people living with plaque psoriasis or inverse psoriasis.
This article looks at which types of psoriasis are most likely to cause skin challenges behind the knees and reviews psoriasis treatment and management strategies.
Psoriasis behind the knees can vary in appearance. It may range from smooth, discolored skin to thickened, scaly plaque patches, depending on which type of psoriasis occurs.
It may also vary in appearance depending on skin color. According to the American Academy of Dermatology Association (AAD), psoriasis may appear in the following colors and forms depending on a person’s skin color:
- pink or red with white or silvery scales
- salmon-colored with silvery or white scales
- violet with gray scales
- dark brown
This type of psoriasis commonly occurs on the torso, knees, elbows, and scalp. The skin patches, known as plaques, can vary in size and often cause itching.
Plaque psoriasis can occur on the front or the back of the knee.
Unlike plaque psoriasis, inverse psoriasis tends to be smooth. It can range in color from red to brown, appearing darker than the skin around it and sometimes shiny.
It exclusively occurs in places with skin folds or skin-on-skin contact, though it may include a wide area of surrounding skin.
Symptoms include a sudden onset of tiny, sometimes scaly, bumps. These bumps can appear clustered together and typically affect large areas of the arms, torso, or legs — including the back of the knee.
Pustular psoriasis causes inflamed patches of skin that develop pus-filled bumps.
While most cases are limited to the hands or the feet, acrodermatitis continua of Hallopeau is a rare form of pustular psoriasis that can slowly spread from the foot up the leg, potentially to the knee.
Another serious form of psoriasis is erythrodermic psoriasis. Most people who develop erythrodermic psoriasis already have another type of psoriasis.
Before developing erythrodermic psoriasis, they often notice that their psoriasis is worsening or not improving with treatment.
As it progresses, erythrodermic psoriasis causes the skin over most of the body, potentially including the backs of the knees, to appear burnt. According to the National Psoriasis Foundation, other symptoms may include:
- rapid pulse
- severe itching
- fluid retention
- poor body temperature regulation
Immediate medical care may be necessary when psoriasis symptoms suddenly worsen or occur alongside signs of illness, since erythrodermic psoriasis can be life threatening.
This condition can cause inflammation, pain, and swelling in one or more joints. A person with this condition may experience symptoms in the knee joints.
The exact causes of psoriasis are unknown. It is an immune-mediated condition, meaning it stems from underlying immune system dysfunction. What causes that immune dysfunction, however, is still unknown.
Despite having unknown origins, psoriasis behind the knee can flare up or worsen due to certain triggers. According to the American Academy of Dermatology Association, common psoriasis triggers include the following:
- alcohol consumption
- skin injury
- weather extremes
- tattoos and piercings
Sweating and skin-on-skin friction
There is no cure for psoriasis, but treatment can relieve symptoms and improve quality of life.
Doctors tailor treatment plans to each person’s psoriasis experience. Doctors will consider the type of psoriasis, its severity, and the areas of the body it affects.
Medications, phototherapy, and mental health care are possible aspects of psoriasis treatment. Not everyone will require every available treatment, and people may see different levels of success using the same therapies.
Some medications help by directly alleviating symptoms such as itching and irritation, while others work systemically, altering immune responses or suppressing cell turnover.
Medications for psoriasis behind the knee
- corticosteroid creams, ointments, or solutions
- vitamin D topicals
- coal tar
- antimetabolites, such as Methotrexate
- biologic response modifiers
- phosphodiesterase 4 (PDE4) inhibitors, which target inflammation and skin cell turnover
Ultraviolet light therapy, also called phototherapy, is an option for psoriasis affecting large areas, such as the legs. It can be done at a care facility or at home under a healthcare professional’s guidance.
However, doctors may not recommend phototherapy for everyone living with psoriasis, including those already using other treatment types. For instance, certain topical medications may increase the risk of sunburn.
Mental health support
As a condition that affects a person’s appearance, psoriasis can cause psychological and physical challenges.
Implementing daily habits and making lifestyle modifications can make a difference when living with psoriasis.
In addition to following treatment plans and visiting a doctor regularly, the
- reducing excess body weight
- limiting alcohol consumption
- quitting smoking
- identifying and avoiding triggers
- bathing or showering in lukewarm water
- keeping skin moisturized with gentle products
- exposing affected skin to small amounts of sunlight
- reducing stress
- joining a support group
Learn more tips for living with psoriasis.
Speaking with a doctor at the first signs of psoriasis may help improve long-term outcomes.
In rare cases, psoriasis can be a medical emergency. Erythrodermic psoriasis can be life threatening, as it disrupts the body’s temperature and fluid balance. Immediate medical attention may be necessary to regulate these disruptions.
Pustular psoriasis that develops over large portions of the body can also be life threatening. Warning signs include:
- sudden onset of body-wide dry, tender skin
- pus-filled lumps covering most of the body
- body-wide oozing pustules that eventually dry and shed to smooth, glazed skin
- muscle weakness
Psoriasis behind the knees is not a unique symptom of one specific type of psoriasis. While the knees are typical locations for plaque psoriasis and inverse psoriasis, other forms of psoriasis can potentially affect the skin on the leg, too.
Receiving a correct diagnosis and creating a treatment plan involves assessing psoriasis symptoms, their severity, and how much of the body is affected.
Keeping skin moisturized and avoiding psoriasis triggers may help a person manage psoriasis behind the knees.