Skin plaques are solid, raised skin lesions that can occur due to various reasons, including inflammatory skin conditions like psoriasis, rashes, infections, or chronic irritation.
The appearance of the plaques can vary, and, in some cases, this can help in identifying the underlying cause. However, in some cases, your doctor may need additional testing to know the cause. Every skin plaque is treated based on what is causing it.
What is a skin plaque?
A skin plaque is a type of skin lesion that is solid, raised, palpable, flat-topped, and more than 1 cm in size. These may have well-defined or ill-defined borders.
Sometimes, plaques are formed when small papules (palpable skin lesions less than 1 cm) come together.
The term “plaque” is acquired from a French word for a plate, and it seems appropriate based on the appearance of plaques.
Plaque vs patch
Both patch and plaque are two terms used in Dermatology for primary skin lesions. A skin plaque is a raised skin lesion that is more than 1 cm, while a patch is a flat lesion that is also more than 1 cm.
For example, psoriasis usually presents with plaques, while melasma presents with patches.
Types
The appearance of skin plaques can vary depending on the cause. It can be of various shapes and may or may not have well-defined borders.
- Annular: Ring shaped like a ringworm.
- Arcuate: The shape of a half-moon.
- Polygonal: Varied non-geometric shapes (non-geometric are natural shapes).
- Polymorphic: Varied shapes.
- Serpiginous: Shape of the snake.
- Poikilodermatous: Variegated appearance (different colors like yellow, red, or dark pigment).
In addition to shapes, the color of the skin plaque may vary too. Most skin rashes present with red plaques (also known as erythematous plaques in medical terminology).
However, some rashes, like tinea versicolor and pityriasis alba, may present with thin hypopigmented or white plaques on the skin.
Symptoms
Plaques can appear anywhere on the body. The underlying cause primarily influences the distribution; for example, psoriasis plaques are often seen on elbows, knees, and scalp.
Plaques may also be associated with other symptoms, which will differ depending on the underlying cause. Some related symptoms may be itching, burning, or tenderness; for example, ringworm rash plaques are associated with intense itching.
Causes
Plaques on the skin can appear due to various skin rashes and conditions. Below you will find 11 causes that can lead to skin plaques, along with their pictures.
1. Psoriasis
Skin plaques which are covered with silvery white scales are often due to psoriasis.
Psoriasis is a chronic inflammatory skin condition. It is of different types, and the appearance of each type can vary.
The most common type is plaque psoriasis. It starts as small red bumps or papules that come together to form large raised areas called plaques. In darker skin tones, the color of the plaque is often darker, gray, or purple.
The red plaques are covered with silvery-white scales and may be associated with itching. The commonly involved areas are elbows, knees, scalp, chest, and back.
The formation of plaques is thought to be due to an immune response. The immune system attacks healthy skin cells, resulting in the overproduction of skin cells. These excess cells do not shed quickly, so they keep accumulating on the skin surface, leading to scaly plaques on the skin.
Cause
The exact cause behind psoriasis is not known. However, it is related to several factors like genetics, the immune system, and environmental factors.
Treatment
The treatment of psoriasis usually includes topicals containing coal tar or salicylic acid. In some cases, topical steroids, immunosuppressants, retinoids, or vitamin D derivatives are prescribed. Phototherapy may also be beneficial.
2. Eczema
Eczema is an inflammatory skin condition that can lead to itching, burning, dry skin, red patches, and plaques. There are various types of eczemas.
Atopic dermatitis is the most common type and is often seen in children (although it can be seen at any age). It may present with red patches on flexural aspects like the front of the elbow or the back of the knee. With chronic itching, one can see thickened skin or plaques.
The exact cause is not known. The associated factors include genetics, skin barrier defect, or altered skin microbiome.
Another type of eczema called discoid or nummular eczema presents with round coin-like spots or plaques. The surface of these lesions may be scaly or crusty. It usually involves legs, arms, or trunk. The scalp and face are usually not involved.
The exact cause behind nummular eczema is not known. It may be associated with factors like injury, allergies, poor circulation, rough fabrics, or certain medications.
Treatment
The treatment includes gentle skincare, skin barrier repair with thick, nourishing moisturizer, and avoiding further skin irritation.
Your doctor may prescribe topical or oral steroids, antihistamines, immunomodulators, other topicals, or light therapy.
3. Seborrheic dermatitis
Seborrheic dermatitis is an inflammatory skin condition that can present with flat red patches or plaques on the skin.
Seborrheic dermatitis plaques are often covered with thick yellow scales and commonly occur in areas rich in sebaceous or oil glands, such as the face, chest, and scalp.
In individuals with darker skin tones, seborrheic dermatitis may lead to hypopigmented areas. Additionally, petaloid seborrheic dermatitis can be seen, which results in arcuate-shaped plaques or patches.
Seborrheic dermatitis is frequently associated with itching.
Cause
The exact cause is not clear; however, the main associated factors include Malassezia (a fungus that is part of the normal flora of our skin), excessive oiliness, and skin barrier dysfunction. It is also associated with certain neurological disorders and medications.
Treatment
The symptoms of seborrheic dermatitis may be controlled with over-the-counter anti-dandruff shampoos containing ingredients like zinc pyrithione, salicylic acid, ketoconazole, etc.
Your doctor may prescribe topical antifungals, steroids, or oral medications in severe cases.
Read more articles on seborrheic dermatitis here.
4. Pityriasis rosea
Pityriasis rosea is a skin rash that may be preceded by flu-like symptoms. It can lead to red patches or plaques on the skin.
The first red patch that appears is called the “Herald patch.” This skin plaque or patch is scaly, oval, or circular and can be up to 10 cm. It usually appears on the chest, back, or abdomen.
Up to 2 weeks later, smaller red spots, which are more widespread, can appear in the form of a Christmas tree.
Pityriasis rosea may be associated with itching.
Cause
The exact cause is not known. There are some theories that include association with certain viruses (like herpesvirus type 6) or medications.
Treatment
Pityriasis rosea is self-limiting, and the rash usually clears on its own in 6-10 weeks. Your doctor may prescribe antihistamines or steroids if the itching is severe.
5. Lichen planus
Lichen planus is a chronic inflammatory condition that can affect the skin, nails, and mucous membranes.
Lichen planus may present with shiny red or purple polygonal plaques that are firm and may be crossed by fine white lines called Wickham striae. One may also see scaly patches.
Cutaneous lichen planus may be associated with itching. The commonly involved areas are the wrist, ankles, and lower back.
Cause
The exact cause is not clear; however, it is thought to occur due to an autoimmune process where our immune cells attack the skin.
The associated factors include genetics, injury, certain medications, viral infections like hepatitis C, or stress.
Treatment
The plaques and patches may disappear on their own. To manage the symptoms, your doctor may prescribe medications like steroids, antihistamines, or immunosuppressants.
6. Ringworm
Ringworm is a fungal infection that can result in red, annular skin plaques, which often form a ring-like pattern, accompanied by scaling. Depending on the part of the body involved, ringworm can have different names; the ringworm of the hands is called tinea manuum, the ringworm of the scalp is called tinea capitis, and so on.
Cause
Ringworm occurs due to infection by fungus dermatophytes. It is very contagious and can spread by direct contact with skin lesions, contaminated surfaces, or soil.
Treatment
The treatment of ringworm includes over-the-counter antifungal ointments with miconazole, terbinafine, or clotrimazole.
In some cases (depending on the severity of the rash and the area involved), prescription topical or oral antifungals may be needed.
Read more articles about ringworm here.
7. Granuloma annulare
Skin plaques with a smooth surface can be due to granuloma annulare. Granuloma annulare is of various types, and the most common type is localized.
This form can lead to red or purple skin plaques, which have smooth surfaces. The center may be slightly depressed. This type commonly involves feet, hands, or fingers. It is not itchy or painful.
It is usually seen in children and young adults.
Cause
The exact cause is not known. The associated factors include sun exposure, injury, insect bites, infection, or certain medications.
Treatment
These red plaques usually resolve over time. Treatments like topical steroids or calcineurin inhibitors, oral medications like steroids or antimalarials, steroid injection, freezing, and laser may help in clearing them faster.
8. Lupus
Cutaneous lupus is a group of disorders that affect the skin. It is commonly seen in females between the ages of 20-50 years.
The three main types are:
- Acute cutaneous lupus: It presents with a red rash in a butterfly pattern (involves cheeks and nose).
- Subacute cutaneous lupus: It presents with scaly red plaques, which may resemble psoriasis. It is commonly seen on sun-exposed areas like the upper arms or trunk.
- Chronic cutaneous lupus: The most common type of this form is discoid lupus. This presents with scaly round red plaques, which can lead to scarring and hair loss. It commonly involves the scalp, ears, cheeks, nose, and lips.
Cause
Lupus is associated with multiple factors like the immune system, genetics, and environment (smoking, sun exposure, certain medications).
Treatment
The treatment may include topical and/or oral steroids, antimalarials, or immunomodulators. One should avoid smoking and protect the skin from the sun.
9. Pityriasis alba
Pityriasis alba is a type of eczema mainly seen in children. It often affects the face (usually cheeks and chin). It may also involve the neck, shoulders, and upper arms.
It leads to round, oval, or irregular patches or sometimes thin plaques. These first appear as pink lesions, then form hypopigmented areas with scales, and finally leave behind smooth hyperpigmented areas.
Cause
The exact cause is not clear. It often coexists with atopic dermatitis.
Treatment
Pityriasis alba usually doesn’t require treatment. The hypopigmented areas regain their color in a few months or years.
Moisturizers and emollients can help with dryness. If needed, steroids may be given for redness and itchiness.
10. Tinea versicolor
Tinea versicolor can lead to scaly white, dark brown, or pink patches or thin plaques. White patches are often seen in darker skin tones. It usually involves the trunk – back, and chest. It may be associated with itching in some people.
Cause
Tinea versicolor occurs due to the overgrowth of the fungus Malassezia. Malassezia is part of the normal flora of our skin. The precipitating factors include excessive sweating, hot & humid climate, pregnancy, stress, and immunosuppression.
Treatment
Mild cases of tinea versicolor are treated with topicals containing antifungal ingredients like miconazole, clotrimazole, ketoconazole, and selenium sulfide.
Oral antifungals may be prescribed if topicals fail to resolve it.
Read more: White spots on skin from fungus.
11. Mycosis fungoides
Rarely, plaques on the skin can be due to mycosis fungoides, a type of skin lymphoma. In this lymphoma, cells in our blood called T-lymphocytes become cancerous and affect our skin.
The symptoms will depend on the progression of the disease. Initially, it may lead to red spots and itching.
As the disease progresses, it can lead to the formation of red or reddish-brown plaques and nodules.
Cause
The exact cause is not clear. Genetics and environmental factors may play a role.
Treatment
Treatment of mycosis fungoides will depend on the stage of the disease. It may include topical or oral medications or radiotherapy.
Diagnosis
Skin plaques may be diagnosed clinically based on their appearance, distribution, and associated symptoms.
However, in some cases, your doctor may recommend additional tests to confirm the diagnosis. These may include:
- Wood lamp examination
- KOH test
- Fungal culture
- Skin biopsy
Key points
Skin plaques are raised thickened areas of skin that can appear due to psoriasis, seborrheic dermatitis, eczema, pityriasis rosea, ringworm, lichen planus, lupus, tinea versicolor, pityriasis alba, and rarely mycosis fungoides (a type of skin lymphoma). The treatment of each will differ depending on the cause.
If you are not sure what is causing the plaques on your skin, it is best to see a doctor for diagnosis and treatment.
References
- Elgash M, Dlova N, Ogunleye T, Taylor SC. Seborrheic Dermatitis in Skin of Color: Clinical Considerations. J Drugs Dermatol. 2019 Jan 1;18(1):24-27. PMID: 30681789.
- Terminology in dermatology. Oakley A. 1997. DermNet.
- Vaidya T, Badri T. Mycosis Fungoides. [Updated 2022 Aug 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan.
Disclaimer: This article is for information purposes only and does not replace medical advice.