What Conditions Can Be Mistaken For Psoriasis?

Psoriasis is challenging to diagnose. Healthcare providers primarily rely on the appearance of the lesions (plaques). These can resemble skin changes caused by other conditions, such as eczema, dermatitis, lupus, and skin cancer.

Also, different types of psoriasis have variations in their appearance, location, and severity. This is why it's common to misdiagnose psoriasis or incorrectly diagnose another condition as psoriasis.

Your symptoms may be due to psoriasis. But here are eight medical conditions your healthcare provider will likely consider before coming to that conclusion.

Doctor and patient at a medical consultation — BURGER / PHANIE / Getty Images

What Can Be Mistaken for Psoriasis

Conditions that may appear similar to psoriasis include:

Eczema
Seborrheic dermatitis
Pityriasis rosea
Lichen planus
Onychomycosis
Lupus
Squamous cell carcinoma
Mycosis fungoides

To avoid misdiagnosis, healthcare providers and dermatologists usually do a differential diagnosis to rule out conditions with symptoms similar to psoriasis. When in doubt, they can exclude other possible causes using blood tests, cultures, skin biopsies, and other tools. This allows them to accurately confirm the diagnosis and start the appropriate treatment.

Eczema

Eczema is the name for a group of conditions that cause red, itchy skin patches similar to psoriasis. As opposed to psoriasis, an autoimmune disorder, eczema is characterized by an overactive (rather than self-destructive) immune response.

Eczema tends to be itchier than psoriasis and can cause oozing and crusting when scratched. With psoriasis, the plaques can easily bleed when scratched, leaving behind a peppered pattern of blood spots known as the Auspitz's sign.

The differences are most apparent under the microscope:

With psoriasis, the skin cells will appear acanthotic (dense and compressed) due to the accelerated speed of skin growth.
With eczema, no such compression will be seen.

Eczema vs. Psoriasis

Eczema tends to be itchier than psoriasis and can cause oozing and crusting when scratched.

With psoriasis, the plaques can easily bleed when scratched, leaving behind a peppered pattern of blood spots known as the Auspitz's sign.

Eczema vs. Psoriasis

Seborrheic Dermatitis

Seborrheic dermatitis is a skin condition that mainly affects the scalp, causing scaly patches of red skin and stubborn dandruff. It's easily mistaken for scalp psoriasis and vice versa.

As with eczema, the conditions can be differentiated under the microscope by their acanthotic or non-acanthotic appearance.

Seborrheic Dermatitis vs. Psoriasis

With seborrheic dermatitis, dandruff flakes are fine and slightly yellowish, while the scalp is oily.

With psoriasis, the flakes are silvery-white with a lamellar (scale-like) appearance. Moreover, psoriatic skin will be dry.

Pityriasis Rosea

Pityriasis rosea is a benign skin condition. The name is Latin for "fine pink scale."

It generally starts with a large, slightly raised, scaly patch on the back, chest, or abdomen. This is called a herald patch. The herald patch is typically followed by the appearance of smaller patches that sweep outward like the boughs of a pine tree.

Pityriasis rosea usually resolves completely within six to eight weeks. Psoriasis is characterized by recurrent flares.

Pityriasis Rosea vs. Psoriasis

The characteristic rash pattern is usually enough to differentiate pityriasis rosea from psoriasis. Psoriasis plaques tend to be far more irregular in shape with a more pronounced scaling.

Lichen Planus

Lichen planus is a skin condition thought to be autoimmune. It causes swelling and irritation in the skin, hair, nails, and mucous membranes. Lichen planus can create lacy white patches when it appears in the mouth, vagina, or other mucosal tissues.

Lichen planus will typically manifest with psoriasis-like lesions on the wrists and limbs.

Under the microscope, psoriasis and lichen planus both have an acanthotic appearance. But with lichen planus, there will be a band-like area of damage between the upper layer of skin (epidermis) and the middle layer (dermis).

Lichen Planus vs. Psoriasis

Lichen planus can be differentiated by the appearance of the skin lesions. They are thick like in psoriasis but are more purple and lack the characteristic scales.

Lichen planus can also affect mucosal tissues, whereas psoriasis won't.

Onychomycosis

Onychomycosis, also known as tinea unguium, is a fungal infection of the nails.

Nail psoriasis is frequently mistaken for onychomycosis. They have similar symptoms, like the thickening, crumbling, and lifting of the nail plate, and the formation of abnormal ridges and dents.

Onychomycosis vs. Psoriasis

One of the first clues that a nail disorder is psoriatic is the appearance of skin plaques elsewhere on the body.

A healthcare provider or dermatologist will take a scraping from the nail and examine it under the microscope to confirm the diagnosis. If there are no fungal spores, it can reasonably be assumed that psoriasis is the cause.

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Lupus

Systemic lupus erythematosus, also known as lupus, is an autoimmune disease that affects multiple organ systems, including the skin.

One of the tell-tale signs of lupus is a rash formation on the cheeks and nose. This is called a butterfly rash.

Healthcare providers can usually confirm lupus with a series of blood tests, including the antinuclear antibody (ANA) test. Skin biopsy, including the use of direct and indirect immunofluorescent tests, can also confirm lupus as the cause.

Lupus vs. Psoriasis

When lupus affects the skin specifically—a condition known as discoid lupus erythematosus—the lesions will be far less scaly than psoriasis and lack the lamellar appearance.

Squamous Cell Carcinoma

Squamous cell carcinoma is the second most common type of skin cancer. It manifests with thick, flat, scaly nodules. It's usually found on areas of the body damaged by ultraviolet (UV) rays from the sun or tanning beds.

Squamous cell carcinoma can readily be diagnosed with a skin biopsy:

Psoriasis will demonstrate the proliferation of keratinocytes (a type of skin cell found in abundance throughout the epidermis).
Squamous cell carcinoma will have a proliferation of squamous cells (the type found mainly on the outer part of the epidermis).

Squamous Cell Carcinoma vs. Psoriasis

Squamous cell carcinoma can mimic psoriasis but tends to be less scaly and limited to areas of sun-damaged skin. Generally, there will only be a handful of cancerous lesions.

Mycosis Fungoides

Mycosis fungoides, also known as Alibert-Bazin syndrome, is the most common form of cutaneous T-cell lymphoma—a dermatological variation of blood cancer known as non-Hodgkin lymphoma.

Mycosis fungoides manifests with rash-like patches of skin.

The lesions will appear scaly and often be extremely itchy in the early stages. The buttocks are often the first part of the body affected. Over time, the lesions can develop elsewhere, causing widespread redness and itching but far less scaling.

A skin biopsy can help differentiate the diseases. With mycosis fungoides, the biopsied tissue will have microscopic pus-filled cavities in the epidermal layer, known as Pautrier abscesses.

Mycosis Fungoides vs. Psoriasis

Mycosis fungoides is easily confused with psoriasis in the early stages.

Unlike psoriasis, mycosis fungoides is often accompanied by persistently swollen lymph nodes. Pancreas and liver enlargement are also common.

See a Healthcare Provider

The problem with misdiagnosis is that it can expose you to unnecessary and unhelpful treatments. Worse, by assuming it's psoriasis without exploring other possible causes, you can miss the signs of a potentially more serious illness. This is why self-diagnosing psoriasis is never a good idea.

If you're worried about a skin condition, ask your healthcare provider for a referral to a dermatologist. Mention both skin-related and non-skin-related symptoms. Doing so increases your chance of reaching the correct diagnosis.

4 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Rendon A, Schäkel K. Psoriasis Pathogenesis and Treatment. Int J Mol Sci. 2019;20(6):1475. doi:10.3390/ijms20061475
Asz-sigall D, Tosti A, Arenas R. Tinea Unguium: Diagnosis and Treatment in Practice. Mycopathologia. 2017;182(1-2):95-100. doi:10.1007/s11046-016-0078-4
Haneke E. Nail psoriasis: clinical features, pathogenesis, differential diagnoses, and management. Psoriasis (Auckl). 2017;7:51–63. doi:10.2147/PTT.S126281
Maidhof W, Hilas O. Lupus: an overview of the disease and management options. P T. 2012;37(4):240–249.

Additional Reading

Kim, W.; Jerome, D.; and Yeung, J. Diagnosis and management of psoriasis. Can Fam Physician. 2017;63(4):278-85.
Young, M.; Aldredge, L.; and Parker, P. Psoriasis for the primary care practitioner. J Am Assn Nurse Pract. 2017;29(3):157-78. doi:10.1002/2327-6924.12443

By Dean Goodless, MD
Dean R. Goodless, MD, is a board-certified dermatologist specializing in psoriasis.

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