Key takeaways
- Psoriasis can be misdiagnosed because its symptoms are similar to those of other skin conditions, such as eczema, seborrheic dermatitis, and ringworm. A correct diagnosis is important for effective treatment.
- It is important to provide an accurate medical history when a doctor or dermatologist asks, as this can help ensure an accurate diagnosis. The more information a medical professional has, the more likely they will be able to diagnose the skin condition correctly.
- Key differentiators between psoriasis and similar conditions include the location and the appearance of the rash. Psoriasis often presents with a scaly rash that can be silvery white, purple, gray, or dark brown, depending on a person’s skin tone.
- If initial treatments fail or symptoms worsen, a dermatologist should be consulted for further tests, such as dermoscopy or a skin biopsy, to confirm the diagnosis.
Psoriasis is one of the most common autoimmune diseases in the United States. The World Psoriasis Day consortium reports the skin condition affects over 125 million people worldwide.
If treatment is not working, a second opinion, further diagnostic tests, or a skin biopsy can help determine whether symptoms are caused by psoriasis or another condition.
This article looks at the different types of psoriasis and other conditions with similar symptoms.
Doctors classify psoriasis and other conditions that have similar effects on the skin as psoriasiform dermatitis.
Even so, it can be difficult for a dermatologist (a doctor who specializes in skin conditions) to tell some of these skin conditions apart.
We discuss some of these conditions in more detail below and explain how they differ from psoriasis.
There are five main types of psoriasis, with a range of different symptoms:
- Plaque psoriasis involves patches of thick, scaly, silvery plaques on the skin. The National Psoriasis Foundation reports research estimates that around 80% to 90% of people with psoriasis have plaque psoriasis.
- Guttate psoriasis involves a large-scale rash consisting of small, reddish bumps.
- Inverse psoriasis involves dry, red, brown, or hyperpigmented (patches of darker skin) scaly patches of skin in the skin folds, such as the armpits and genitals. Inverse psoriasis causes thinner scales than plaque psoriasis.
- Pustular psoriasis involves pus-filled blisters forming on a person’s skin.
- Erythrodermic psoriasis is an aggressive form of psoriasis that causes widespread skin peeling, intense burning, fever, and inflammation.
Plaque psoriasis causes skin cells to multiply faster than usual. Symmetrical, well-defined areas of inflamed skin with flaking, silvery white scaly plaques that may itch characterize it. These patches usually develop on the outer elbows and knees, lower back, hands, and scalp.
People with psoriasis may notice the Koebner phenomenon, where areas of psoriasis develop in places where a skin injury has occurred.
Doctors may misdiagnose or confuse psoriasis with eczema and vice versa. This is because they have a similar appearance, and dermatologists often base their diagnosis on a visual exam.
They will usually discuss a person’s medical history, as well, which can often be the same for psoriasis and eczema.
However, a dermatologist can typically distinguish between eczema and plaque psoriasis by looking at the specific symptoms and their location.
Eczema is more likely to affect the insides of the arms and knees, while psoriasis often occurs on the outside of the elbows and knees, lower back, and scalp.
Compared with eczema, psoriasis tends to affect more well-defined areas of skin. Another distinguishing factor is the intensity of itch, which is typically more intense in eczema than in psoriasis.
Seborrheic dermatitis is a form of eczema that often affects the scalp. It causes rough, scaly skin to develop on the face and scalp.
Seborrheic dermatitis can cause similar symptoms to scalp psoriasis, such as:
- flaking skin on the scalp
- patches of itchy skin that can be inflamed
- areas of skin redness or hypopigmentation (loss of skin color)
While psoriasis tends to cause thick, white scales to develop, seborrheic dermatitis produces thinner, slightly greasy-looking yellowish skin flakes.
Pityriasis rubra pilaris refers to a group of skin conditions that cause inflammation and scaling.
Similarly to plaque psoriasis, symptoms of pityriasis rubra pilaris develop on the palms of the hands, the scalp, and the soles of the feet. People may also notice their nails become thickened and discolored.
A dermatologist may be able to tell these conditions apart by using dermoscopy. This procedure involves looking closely at the skin with a specialized handheld microscope without the need for a skin biopsy.
Ringworm (tinea corporis) is an infection caused by a group of fungi called dermatophytes, not an actual worm.
Ringworm and psoriasis both cause scaly patches of skin. When these patches are more circular and uniform, ringworm rather than psoriasis may be the cause.
Jock itch (tinea cruris) is a form of ringworm. It causes a scaly rash in places where the skin folds and sweat accumulates.
The areas that jock itch favors are the groin and the inner thighs. These are the same spots that inverse psoriasis affects.
Smooth, red, shiny patches on folds of the skin, such as under the arm, in the inner thighs, or around the groin, characterize inverse psoriasis.
Tinea versicolor is a fungal infection that causes small, red, sometimes scaly marks on the skin. People may confuse tinea versicolor with guttate psoriasis, which produces similar small red marks.
Tinea versicolor can also cause patches of light and dark skin, and people can confuse it with vitiligo.
Both pityriasis rosea and plaque psoriasis cause patches of scaly rash on the skin. Pityriasis rosea is characterized by one large, scaly patch, which doctors refer to as the mother patch, and smaller patches they call daughter patches.
Lupus and psoriasis are both autoimmune conditions. Both cause skin rashes, though lupus also affects the internal organs. Lupus is also less common and more severe than psoriasis.
Lupus can be confused with psoriatic arthritis, as both conditions can cause joint pain. Psoriatic arthritis is a type of arthritis.
It is not common for a doctor to misdiagnose skin cancer and psoriasis. If a doctor suspects skin cancer, diagnostic tests are performed to find out more.
Some types of skin cancer, such as basal cell carcinoma and squamous cell carcinoma, can cause scaly, rough, or raised areas of skin that may itch.
It is unlikely that a person would mistake melanoma for psoriasis, as the symptoms are different.
Depending on the specific symptoms, people can receive a misdiagnosis of different types of psoriasis.
Plaque psoriasis might be confused with one of the following conditions:
- lichenified dermatitis, where a person’s skin becomes thicker, hyperpigmented (darker than other skin), and takes on a leather-like appearance and feel
- secondary syphilis, which includes a skin rash plus swollen lymph nodes and fever
- mycosis fungoides, a rare type of skin cancer
- inflammatory linear verrucous epidermal nevus, a genetic skin condition.
Inverse psoriasis can also mimic:
- intertriginous cutaneous candidiasis
- dermatophytosis, a fungal infection
- benign familial chronic pemphigus (Hailey-Hailey disease), a genetic disorder that causes blistering
Pustular psoriasis is distinguished by its white blisters on a person’s skin, most commonly found on their hands or feet.
This form of psoriasis
Erythrodermic psoriasis is a severe form of psoriasis, showing widespread areas of red, very sore, itchy skin. It can mimic other inflammatory skin conditions that cause widespread redness of a person’s skin, a symptom known as erythema.
Psoriasis affects men and women equally. It often develops before
Psoriasis is more common in white people (3.6%) compared with African American people (1.5%). People with a family member who has psoriasis are also more likely to develop it.
Providing an accurate history when a doctor or dermatologist asks is essential in helping ensure an accurate diagnosis is received. The more information a medical professional has to work with, the more likely they are to diagnose an illness correctly.
This is especially important with skin conditions like psoriasis. Medical history and a visual assessment are often used to diagnose a skin condition. A visual assessment alone may not be enough.
If the diagnosis of psoriasis is still unclear, further diagnostic tests, such as a dermoscopic exam or skin biopsy, may be required.
If a person has psoriasis and treatment is not working, or their symptoms are getting worse, they may have received a misdiagnosis.
Or they may not have yet found the treatment that works best for them. Different people respond differently to the range of possible psoriasis treatments.
Speak with a doctor or dermatologist to discuss any concerns regarding a psoriasis diagnosis or misdiagnosis.