Psoriasis differential diagnosis

Acne is a common skin condition that causes spots, clogged pores, and inflammation. It can appear on the face, chest, shoulders, or back, and may come and go over time. Acne is not contagious, and many people find their symptoms improve with supportive skincare and the right guidance.

Acne develops when hair follicles become clogged with oil and dead skin cells. This can lead to different types of spots, ranging from small blocked pores to inflamed bumps.

Common signs include:

• Blackheads (open clogged pores)
• Whiteheads (closed clogged pores)
• Red, inflamed bumps
• Tender spots that may feel sore
• Occasional cysts or deeper lumps

Acne can vary from mild to more noticeable and may flare with hormones, stress, or certain skincare products.

Why acne matters in psoriatic disease

Acne is important to recognise because:

• It can be mistaken for folliculitis, keratosis pilaris, or small psoriasis bumps, especially on the chest or back.
• People with psoriasis may worry that new spots mean their condition is worsening.
• Some treatments used for psoriasis or arthritis may affect the skin, making acne more noticeable.
• Acne can overlap with other inflammatory skin conditions, making diagnosis less straightforward.
• Understanding acne helps people feel more confident about what’s happening with their skin and when to seek advice.

What can I do about it?

Acne is manageable, and many people find their symptoms improve with supportive strategies. A healthcare professional can help confirm the cause of spots and discuss suitable options.

General approaches often include:

• Gentle skincare, avoiding harsh scrubbing
• Non‑comedogenic products, if advised
• Avoiding picking or squeezing, which can irritate the skin
• Monitoring flare patterns, such as stress or hormonal changes

Where can I get help?

If you’re unsure whether your spots are acne, folliculitis, psoriasis‑related, or something else or if breakouts are persistent or affecting daily life support is available.

You can:

• Speak to your GP
• Ask for a referral to dermatology if symptoms are persistent or unclear
• Request a review of your psoriasis care plan if you’re concerned about overlapping skin changes.

Contact dermatitis is a skin reaction that happens when the skin comes into contact with something that irritates it or triggers an allergic response. It causes redness, itching, dryness, and sometimes small blisters or cracking. Contact dermatitis is not contagious, and many people find their symptoms improve once the trigger is identified and avoided.

Contact dermatitis occurs when the skin becomes inflamed after touching a particular substance. There are two main types:

• Irritant contact dermatitis caused by things that physically irritate the skin (like soaps, detergents, or friction).
• Allergic contact dermatitis caused by the skin reacting to something it is sensitive to (like nickel, fragrances, or certain plants).

Common signs include:

• Red, itchy patches
• Dry or cracked skin
• Small bumps or blisters
• Burning or stinging
• A clear link to something that touched the skin, though this is not always obvious

Symptoms may appear quickly or develop over several hours.

Why contact dermatitis matters in psoriatic disease

Contact dermatitis is important to recognise because:

• It can be mistaken for psoriasis, especially when patches are red and scaly.
• People with psoriasis may worry that new irritated areas mean their condition is worsening.
• Some treatments or skincare products used for psoriasis may occasionally irritate sensitive skin, leading to contact dermatitis.
• Contact dermatitis behaves differently from psoriasis it is often itchier, more irritated, and linked to a specific trigger.
• Understanding contact dermatitis helps people feel more confident about what’s happening with their skin and when to seek advice.

What can I do about it?

Contact dermatitis is manageable, and many people find their symptoms improve with supportive strategies. A healthcare professional can help confirm the cause of skin changes and discuss suitable options.

General approaches often include:

• Gentle skincare, avoiding harsh soaps or scrubbing
• Moisturising to support the skin barrier
• Avoiding known triggers, if identified
• Protecting the skin, such as using gloves for irritants

Where can I get help?

If you’re unsure whether your skin changes are contact dermatitis, psoriasis, eczema, or something else — or if patches are persistent, itchy, or affecting daily life — support is available.

You can:

• Speak to your GP
• Ask for a referral to dermatology if symptoms are unclear or persistent
• Request a review of your psoriasis care plan if you’re concerned about overlapping skin changes.

Cutaneous T‑cell lymphoma (CTCL) is a rare condition where certain immune cells (T‑cells) behave abnormally and affect the skin. It often causes dry, scaly patches, thin plaques, or itchy areas that can look similar to eczema or psoriasis. CTCL is not contagious, and many people live well with the

CTCL begins in the skin rather than in the blood or lymph nodes. The affected T‑cells gather in the skin and cause persistent patches or plaques that may slowly change over time.

Common signs include:

• Dry, scaly patches that may resemble eczema or psoriasis
• Thin plaques that can be pink, red, or brown
• Itching, sometimes significant
• Areas that persist for months or years
• Skin that may feel sensitive or irritated

CTCL often develops gradually, and symptoms can vary widely from person to person.

Why CTCL matters in psoriatic disease

CTCL is important to recognise because:

• Early CTCL can look very similar to psoriasis, eczema, or parapsoriasis, making diagnosis challenging.
• People with psoriasis may worry that new or persistent patches mean their condition is worsening.
• Treatments for psoriasis or eczema may not work in the same way for CTCL.
• CTCL requires specialist dermatology follow‑up, even when mild.
• Understanding CTCL helps people feel more confident about what’s happening with their skin and when to seek advice.

What can I do about it?

CTCL is manageable, and many people find their symptoms improve with supportive care. A healthcare professional can help confirm the diagnosis and discuss suitable options.

General approaches often include:

• Gentle skincare, such as regular moisturising
• Avoiding irritation, like harsh soaps or friction
• Monitoring patches for any changes

Where can I get help?

If you’re unsure whether your skin patches are CTCL, psoriasis, eczema, or something else or if the areas are changing or persistent support is available.

You can:

• Speak to your GP
• Ask for a referral to dermatology for assessment and monitoring
• Request a review of your psoriasis care plan if you’re concerned about overlapping symptoms.

Eczema (also called atopic dermatitis) is a condition where the skin barrier doesn’t work as well as it should. This makes the skin dry, sensitive, and more reactive to everyday triggers like soaps, cold weather, or allergens.

Common signs include:

• Dry, cracked skin

• Intense itching  often the main symptom

• Red, inflamed patches

• Less sharply defined edges than psoriasis

• Common on the hands, face, elbows, and behind the knees

Eczema often starts in childhood but can appear at any age.

Why it is relevant to psoriatic disease

Eczema is especially important to understand if you live with psoriasis or psoriatic arthritis because:

• The two conditions can occur together.

• Eczema can mask psoriasis, especially in children.

• Scalp eczema may look like sebopsoriasis, making diagnosis harder.

• Treatments differ  what helps eczema may not help psoriasis.

• Misunderstanding the symptoms can delay the right care.

What can I do about it?

Both eczema and psoriasis are manageable, and many people find good control with the right approach. A healthcare professional can help you understand which condition is present and discuss suitable options.

• Moisturisers to repair the skin barrier

• Avoiding irritants such as harsh soaps

• Short courses of topical steroids

• Calcineurin inhibitors for sensitive areas

Where can I get help?

If you’re unsure whether your symptoms are eczema, psoriasis, or a mix of both, or if your skin isn’t responding to treatment, support is available.

You can:

• Speak to your GP or dermatology team

• Ask for a review of your psoriasis or psoriatic arthritis care plan

• Request a referral if symptoms are persistent or unclear

Hives also called urticaria are raised, itchy welts that appear suddenly on the skin. They may look red, pink, or skin‑coloured and often come and go within hours. Hives are not contagious, and many people find their symptoms settle with time and supportive care.

Hives happen when the skin releases natural chemicals that cause swelling and itch. They can appear anywhere on the body and may change shape, size, or location over a short period.

Common signs include:

• Raised, itchy welts
• Red or skin‑coloured patches
• Areas that come and go quickly
• Welts that may join together into larger patches
• Itching, sometimes intense

Some people also notice temporary swelling of the lips, eyelids, or hands.

Why hives matter in psoriatic disease

Hives are important to recognise because:

• They can be mistaken for psoriasis flares, eczema, or allergic rashes.
• People with psoriasis may worry that new itchy patches mean their condition is worsening.
• Certain medications used for psoriasis or arthritis may occasionally cause skin reactions, so recognising hives can help guide conversations with clinicians.
• Hives behave differently from psoriasis  they move around, appear suddenly, and fade quickly.
• Understanding hives helps people feel more confident about what’s happening with their skin and when to seek advice.

What can I do about it?

Hives are often short‑lived, and many people find their symptoms improve with supportive strategies. A healthcare professional can help confirm the cause and discuss suitable options.

General approaches often include:

• Gentle skincare, avoiding harsh soaps or friction
• Cool compresses to soothe itch
• Avoiding known triggers, if identified
• Monitoring patterns, such as foods, stress, or temperature changes

Where can I get help?

If you’re unsure whether your skin changes are hives, psoriasis, eczema, or something else  or if the welts are persistent, severe, or affecting daily life  support is available.

You can:

• Speak to your GP
• Ask for a referral to dermatology if symptoms are persistent or unclear
• Request a review of your psoriasis care plan if you’re concerned about overlapping skin changes.

Nummular eczema, also called discoid eczema is a skin condition that causes round or oval patches of dry, inflamed skin. These patches can be itchy, scaly, or cracked, and often appear on the arms, legs, or trunk. Nummular eczema is not contagious, and many people find their symptoms improve with supportive skincare and guidance.

Nummular eczema develops when the skin becomes very dry and inflamed, forming distinct coin‑shaped patches. These areas may be red, flaky, or sometimes weepy if the skin barrier is very irritated.

Common signs include:

• Round or oval patches of inflamed skin
• Dryness and flaking
• Itching, which may be mild or noticeable
• Cracked or rough skin
• Patches that may persist for weeks or months

The patches can vary in size and may appear singly or in clusters.

Why nummular eczema matters in psoriatic disease

Nummular eczema is important to recognise because:

• It can be mistaken for plaque psoriasis, especially when patches are scaly.
• People with psoriasis may worry that new round patches mean their condition is worsening.
• Nummular eczema behaves differently from psoriasis — it is often very dry, more itchy, and has softer edges.
• Treatments for psoriasis may not work in the same way for nummular eczema.
• Understanding nummular eczema helps people feel more confident about what’s happening with their skin and when to seek advice.

What can I do about it?

Nummular eczema is manageable, and many people find their symptoms improve with supportive strategies. A healthcare professional can help confirm the cause of skin changes and discuss suitable options.

General approaches often include:

• Gentle skincare, such as regular moisturising
• Avoiding harsh soaps, fragrances, or irritants
• Protecting the skin from dryness and cold weather
• Monitoring flare patterns, such as stress or winter dryness

Where can I get help?

If you’re unsure whether your skin patches are nummular eczema, psoriasis, or something else or if the areas are persistent, itchy, or affecting daily life support is available.

You can:

• Speak to your GP
• Ask for a referral to dermatology if patches are unclear or persistent
• Request a review of your psoriasis care plan if you’re concerned about overlapping symptoms.

Parapsoriasis is a group of long‑lasting skin conditions that cause flat, scaly patches or thin plaques on the skin. These patches are usually mildly itchy or not itchy at all, and tend to persist for months or years. Parapsoriasis is not contagious, and many people find their symptoms manageable with the right support.

Parapsoriasis refers to skin conditions that look similar to psoriasis but behave differently. The patches are often thin, dry, and lightly scaly, and may appear on the trunk, arms, or legs.

Common signs include:

• Flat or slightly raised patches
• Fine scale rather than thick scale
• Mild or no itch
• Persistent areas that don’t change quickly
• Patches that may be oval or map‑like in shape

There are two main types small‑plaque and large‑plaque parapsoriasis which differ mainly in the size of the patches.

Why parapsoriasis matters in psoriatic disease

Parapsoriasis is important to recognise because:

• It can be mistaken for psoriasis, especially when patches are scaly.
• People with psoriasis may worry that new patches mean their condition is worsening.
• Large‑plaque parapsoriasis can sometimes need closer monitoring, so recognising it early is helpful.
• Treatments for psoriasis may not work in the same way for parapsoriasis.
• Understanding parapsoriasis helps people feel more confident about what’s happening with their skin and when to seek advice.

What can I do about it?

Parapsoriasis is manageable, and many people find their symptoms improve with supportive strategies. A healthcare professional can help confirm the diagnosis and discuss suitable options.

General approaches often include:

• Gentle skincare, such as moisturising
• Avoiding irritation, like harsh soaps or friction
• Pacing sun exposure, if advised by a clinician
• Monitoring patches for any changes

A clinician may discuss additional options depending on individual needs.

Where can I get help?

If you’re unsure whether your skin patches are parapsoriasis, psoriasis, or something else or if the areas are changing or persistent support is available.

You can:

• Speak to your GP
• Ask for a referral to dermatology if patches are persistent or unclear
• Request a review of your psoriasis care plan if you’re concerned about overlapping symptoms.

Pityriasis rosea is a temporary skin condition that causes a distinctive rash, often beginning with a single larger patch followed by smaller ones. It can look worrying, but it is harmless, not contagious, and usually clears on its own within several weeks.

Pityriasis rosea typically starts with a “herald patch”, a single, round or oval area of pink or salmon‑coloured skin. A few days later, smaller patches appear on the chest, back, or upper arms, often forming a gentle “Christmas‑tree” pattern.

Common signs include:

• A single larger patch (the herald patch)

• Multiple smaller patches that follow

• Mild itching

• Pink, salmon, or slightly scaly areas

• A pattern that often spreads across the trunk

The rash usually lasts 6–12 weeks and then fades without treatment.

Pityriasis rosea is important to recognise because:

• It can look similar to guttate psoriasis, especially in the early stages.

• The herald patch can be mistaken for a psoriasis plaque.

• People with psoriatic disease may worry that the rash is a new flare or a sign of worsening inflammation.

• Misunderstanding the rash can lead to unnecessary concern or delayed reassurance.

What can I do about it?

Pityriasis rosea is self‑limiting, meaning it usually gets better on its own. Treatment focuses on easing symptoms while the rash settles.

Where can I get help?

If you’re unsure whether your rash is pityriasis rosea, psoriasis, or something else, or if the rash is spreading or causing discomfort, support is available.

You can:

• Speak to your GP or dermatology team

• Ask for a review of your psoriasis or psoriatic arthritis care plan if you’re concerned about a flare

• Request a referral if symptoms are persistent or unclear

Pityriasis rubra pilaris (PRP) is a rare inflammatory skin condition that causes redness, scaling, and thickened patches of skin. It can affect small areas or spread more widely across the body. Although PRP can look alarming, it is not contagious, and many people find their symptoms improve gradually over time.

PRP happens when the skin’s natural growth cycle becomes overactive, leading to inflammation and a build‑up of thick, scaly patches. The exact cause isn’t fully understood, but it is thought to involve immune system changes, genetic factors, and sometimes triggers such as infections.

Common signs include:

• Red‑orange patches on the body
• Thickened areas of skin, especially on the palms and soles
• Follicular bumps, small rough bumps around hair follicles
• Areas of normal skin appearing between patches (islands of sparing)
• Scaling that may be fine or coarse
• Nail changes, such as thickening or discolouration, in some people

PRP can vary widely from person to person. Some people have mild symptoms, while others may experience more widespread involvement.

Why it is relevant to psoriatic disease
PRP is important to recognise because:

• It can look very similar to psoriasis, especially when the skin becomes red and scaly.
• Severe PRP can resemble erythrodermic psoriasis, making diagnosis challenging.
• Nail changes in PRP may be mistaken for nail psoriasis.
• People with psoriatic disease may worry that widespread redness or thickening is a psoriasis flare.
• Treatments differ, what helps psoriasis may not help PRP, so getting the right diagnosis matters.

Understanding PRP helps people with psoriatic disease feel more confident about what’s happening on their skin and when to seek advice.

What can I do about it?

PRP is manageable, and many people find their symptoms improve with the right approach. A healthcare professional can help confirm the diagnosis and discuss suitable options.

General approaches often include:

• Topical treatments to reduce scaling and soothe the skin
• Topical steroids to calm inflammation
• Gentle skincare to reduce irritation
• Avoiding harsh soaps or fragranced products
• Moisturisers to support the skin barrier

Where can I get help?

If you’re unsure whether your symptoms are eczema, psoriasis, or a mix of both, or if your skin isn’t responding to treatment, support is available.

You can:

• Speak to your GP or dermatology team

• Ask for a review of your psoriasis or psoriatic arthritis care plan

• Request a referral if symptoms are persistent or unclear

Seborrhoeic dermatitis is a skin condition that sits between psoriasis and dermatitis and is called Sebopsoriasis. It causes redness, flaking, and thicker patches in oily areas of the skin especially the scalp, face, ears, and chest. Many people find it confusing because it looks like both conditions at once.

Sebopsoriasis happens when the skin shows features of psoriasis (thicker, more defined plaques) and seborrhoeic dermatitis (greasy, yellowish scale) at the same time. It is not a separate disease, it’s an overlap pattern that can appear in people with psoriasis or in those who have never had psoriasis before.

Common signs include:

• Scalp flaking that is thicker than dandruff

• Redness and irritation around the nose, eyebrows, ears or hairline

• Greasy or yellowish scale

• Itching that may come and go

• It is very common in people with psoriasis, especially those with scalp involvement.

• It can be the first sign of psoriasis for some people.

• It can make diagnosis harder, the skin may not look “typically psoriatic,” which can delay treatment.

• It often flares during times of stress, cold weather, or changes in immune activity, which are also common triggers in psoriatic disease.

What can I do about it?

Sebopsoriasis is manageable, and many people find good control with the right approach. Treatment usually combines strategies for both psoriasis and seborrhoeic dermatitis.

Where can I get help?

If you think you may have sebopsoriasis or your current treatment isn’t working well, support is available.

You can:

• Speak to your GP or dermatology team

• Ask for a review of your psoriasis or psoriatic arthritis care plan

• Request a referral if symptoms are persistent or unclear

Skin cancer is a condition where skin cells grow in an abnormal, uncontrolled way. It often appears as a new lump, patch, or sore that doesn’t heal. Most types of skin cancer develop slowly and can be treated effectively when found early. Skin cancer is not contagious, and many people do well with the right care and monitoring.

Skin cancer begins when certain skin cells start to grow differently from normal. There are several types, but the most common are basal cell carcinoma, squamous cell carcinoma, and melanoma.

Common signs include:

• A new lump or bump that slowly grows
• A patch that bleeds, crusts, or doesn’t heal
• A mole that changes in size, shape, or colour
• A sore that keeps coming back
• A rough or scaly area that feels different from surrounding skin

Changes may appear anywhere but are more common on sun‑exposed areas such as the face, ears, neck, arms, and hands.

Why skin cancer matters in psoriatic disease

Skin cancer is important to recognise because:

• Some skin cancers can look similar to psoriasis patches, eczema, or other inflammatory conditions.
• People with psoriasis may worry that new skin changes mean their condition is worsening.
• Treatments for psoriasis — especially long‑term phototherapy — may require routine skin checks.
• Persistent patches that don’t behave like psoriasis may need assessment.
• Understanding skin cancer helps people feel more confident about what’s happening with their skin and when to seek advice.

What can I do about it?

Skin cancer is treatable, especially when found early. A healthcare professional can help confirm the cause of any skin change and discuss suitable options.

General supportive approaches often include:

• Gentle skincare, avoiding irritation
• Monitoring patches or moles for changes
• Sun protection, such as clothing or shade
• Attending skin reviews, if recommended

Where can I get help?

If you’re unsure whether a skin change is psoriasis, eczema, CTCL, or something else — or if a patch, lump, or mole is new, changing, or persistent — support is available.

You can:

• Speak to your GP
• Ask for a referral to dermatology for assessment
• Request a review of your psoriasis care plan if you’re concerned about overlapping symptoms.

Tinea infections often called ringworm, athlete’s foot, or fungal skin infections are common, contagious fungal infections that cause red, scaly, itchy patches on the skin. Despite the name “ringworm,” there is no worm involved. These infections are usually mild and respond well to treatment.

Tinea infections happen when a group of fungi called dermatophytes grow on the skin, nails, or scalp. They thrive in warm, moist areas and can spread through skin‑to‑skin contact, shared towels, or contaminated surfaces.

Common signs include:

• Ring‑shaped patches with a raised, scaly edge
• Itching, which may be mild or bothersome
• Red or flaky skin
• Cracking or peeling between the toes (athlete’s foot)
• Thickened, discoloured nails in nail infections
• Scalp scaling that may cause patchy hair loss

Tinea can appear anywhere on the body and may affect one area or several.

Why it is relevant to psoriatic disease

Tinea infections are important to recognise because:

• They can look similar to psoriasis, especially when the patches are red and scaly.
• Ring‑shaped tinea can be mistaken for guttate or plaque psoriasis.
• Scalp tinea may resemble sebopsoriasis or scalp psoriasis.
• Nail tinea can be confused with nail psoriasis, making diagnosis harder.
• People with psoriatic disease may worry that a new rash is a psoriasis flare.
• Treatments differ, antifungal medicines are needed for tinea, while psoriasis treatments will not clear a fungal infection.

Understanding tinea helps people with psoriatic disease feel more confident about what’s happening on their skin and when to seek advice.

What can I do about it?

Tinea infections are treatable, and most people improve quickly with the right approach. A healthcare professional can help confirm the diagnosis and discuss suitable options.

General approaches often include:

• Antifungal creams for mild skin infections
• Keeping the skin clean and dry
• Avoiding shared towels or clothing
• Wearing breathable footwear for athlete’s foot
• Gentle skincare to reduce irritation

For scalp or nail infections, a clinician may discuss additional options depending on severity.

Where can I get help?

If you’re unsure whether your symptoms are tinea, psoriasis, or something else, or if your rash is spreading, painful, or not improving, support is available.

You can:

• Speak to your GP or dermatology team
• Ask for a review of your psoriasis or psoriatic arthritis care plan if you’re concerned about a flare
• Request a referral if symptoms are persistent or unclear