Pityriasis lichenoides chronica

Definition

Pityriasis lichenoides chronica (PLC) is a skin disease that causes the development of small, scaling, raised spots (papules) on the skin. PLC is the relatively mild form of the disease pityriasis lichenoides.

Cause

• The exact cause of pityriasis lichenoides chronica (PLC) is not well-understood.
• In some cases, people with PLC have also had infections including Epstein-Barr virus (EBV), toxoplasmosis, cytomegalovirus, and human immunodeficiency virus (HIV).
• It is thought that these infections may increase the risk of developing PLC.
• In some cases, people have developed PLC after taking medications such as chemotherapy or hormone replacement therapy.
• These medications may also increase the risk of developing PLC.
• There is some evidence that PLC could be caused by the overgrowth of cells of the lymphatic system (lymphoproliferative disorder).
• PLC could also be caused by a reaction of the immune system against the body’s own tissues (autoimmune response).
• However, the cause of PLC may be different for different people with the disease, and the exact cause of the disease may not be determined for each person. PLC is not contagious, so it cannot be spread by coming in contact with a person who has the skin papules.

Inheritance

• Pityriasis lichenoides chronica (PLC) is not thought to be passed directly from parents to children.
• This is because there is not one specific gene in which changes are thought to cause PLC.
• The development of PLC may be associated with having certain kinds of infections, or it may be caused by the immune system attacking the tissues of the body (autoimmune response).
• In general, autoimmune responses are thought to be caused by a combination of genetic and environmental factors.
• If the cause of PLC can be determined for a specific person and family members have similar risk factors, they may have an increased risk to develop PLC as well.

Signs and symptoms

• The signs and symptoms of pityriasis lichenoides chronica (PLC) include the development of papules on the skin.
• The papules typically begin as small, firm, pink spots, and they may have a scaly layer on the top.
• Over time, the papules typically turn brown in color and eventually fade. This process may occur over a few weeks.
• The most common locations for the papules are the trunk, buttocks, arms, and legs.
• Rarely, the papules may also occur on the hands, feet, face, and scalp.
• The papules typically are located in groups, and are generally not painful or itchy.
• The papules can resemble those associated with psoriasis, chicken pox, or insect bites.
• PLC is a chronic disease, meaning that some people experience the development of new papules after old papules have faded.
• This can last for several months to several years.
• PLC most commonly affects adolescents and young adults.
• The disease may be slightly more common in males.

Diagnosis

• Pityriasis lichenoides chronica (PLC) may be suspected when a doctor, most often a dermatologist, observes papules on the skin that look like those associated with PLC.
• These papules can also look like those that are caused by other diseases including psoriasis, chicken pox, or insect bites.
• Therefore, a skin biopsy may be recommended to confirm the diagnosis.

Treatment

In some cases, pityriasis lichenoides chronica (PLC) may fade over time without requiring any treatment. In other cases, people with PLC may want treatment because there are many papules that are taking a long time to fade.

Possible therapies that may be used to treat PLC include:

• Exposure to sunlight while carefully avoiding sunburn
• Steroid creams
• Oral antibiotics
• Phototherapy
• Photochemotherapy: a treatment that uses a combination of psoralens and ultraviolet radiation
• If these therapies do not help treat PLC, other treatments may be used including oral steroids and immunosuppressants.
• In some cases, PLC may not respond to treatment, and relapses may occur. If the papules do return, close follow-up with a dermatologist is recommended.

Prognosis

• Most people with pityriasis lichenoides chronica (PLC) notice that their symptoms improve over time.
• The exact amount of time that people have symptoms of the disease can vary, but typically the papules are present for several months to a few years. In some cases, the papules may disappear and reappear (relapse) over time.
• For some people, treatment helps to shorten the duration of the disease.
• Some treatments, such as steroids or antibiotics, may cause side-effects.
• Some people may need to try a combination of treatments to find what works best in relieving the symptoms.
• In some cases, treatment may not relieve the symptoms of PLC.
• Rarely, people with PLC may develop a specific type of lymphoma of the skin (cutaneous lymphoma).

NIH genetic and rare disease info

• NIH info on Pityriasis lichenoides chronica

Pityriasis lichenoides chronica is a rare disease.

Pityriasis lichenoides chronica Resources
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