What is psoriasis and what types are there? 

Psoriasis is a long term skin condition that affects many people across the UK, resulting in patches of skin that may be flaky, scaly, or sore. It is an immune-mediated condition, meaning the body’s immune system mistakenly attacks healthy skin cells, causing them to regenerate at an unnaturally rapid rate. While many people are familiar with the most common form of the condition, there are actually several different types, each presenting with unique physical characteristics and affecting different areas of the body. Recognising these specific types is a vital step in understanding how the condition may progress and how it is typically managed within the healthcare system. 

What We’ll Discuss in This Article 

• The biological process that defines psoriasis as an immune condition. 

• The appearance and symptoms of plaque psoriasis. 

• Characteristics of guttate psoriasis and its common triggers. 

• How inverse and pustular psoriasis differ from common types. 

• The impact of scalp and nail psoriasis. 

• Erythrodermic psoriasis and when it requires urgent care. 

What is the underlying cause of psoriasis? 

Psoriasis is caused by an increased production of skin cells. In a typical cycle, skin cells are created and replaced every three to four weeks. However, for those with psoriasis, this process is accelerated to just a few days. This rapid turnover causes immature skin cells to build up quickly on the surface of the skin, creating raised, crusty patches covered with scales. Research indicates that this is driven by problems with the immune system, specifically T-cells, which normally protect the body against infection but instead trigger inflammation in the skin. Genetic factors and environmental triggers also play a role in how and when the condition appears. 

What is plaque psoriasis? 

Plaque psoriasis, also known as psoriasis vulgaris, is the most common form of the condition, affecting around 80 to 90 percent of people with psoriasis. It is characterised by dry, red skin lesions, known as plaques, which are covered in silvery scales. These plaques can be itchy or sore, and in severe cases, the skin around the joints may crack and bleed. Plaque psoriasis most frequently appears on the elbows, knees, scalp, and lower back, though it can occur anywhere on the body. 

What is guttate psoriasis? 

Guttate psoriasis is often seen in children and young adults. It typically appears as small, drop-shaped, red sores on the chest, arms, legs, and scalp. These sores are not usually as thick as the lesions found in plaque psoriasis. This specific type of psoriasis is frequently triggered by a bacterial infection, most commonly a streptococcal throat infection. While a flare-up of guttate psoriasis may disappear completely after a few weeks, some individuals go on to develop plaque psoriasis later in life. 

What are inverse and pustular psoriasis? 

Inverse psoriasis, or flexural psoriasis, affects areas where the skin folds, such as the armpits, groin, and under the breasts. Unlike other types, it appears as smooth, bright red patches of skin that are not scaly, primarily because of the moisture and friction in these areas. Pustular psoriasis is a rarer form that causes white, pus-filled blisters to appear on the skin. These blisters are surrounded by red skin and are not infectious. Pustular psoriasis can be localised to the palms and soles of the feet or, in very rare cases, can spread across the entire body. 

How does psoriasis affect the scalp and nails? 

Scalp psoriasis can occur alongside plaque psoriasis or on its own. It appears as reddish patches of skin covered with thick, silvery-white scales that can be mistaken for dandruff. In some cases, it can lead to temporary hair thinning if the scales are very thick or if the area is scratched frequently. Nail psoriasis affects about half of all people with the condition. Symptoms include tiny dents or pits in the nails, discolouration, or the nail crumbling and detaching from the nail bed. This can sometimes be a precursor to psoriatic arthritis, a related condition affecting the joints. 

What is erythrodermic psoriasis? 

Erythrodermic psoriasis is the rarest and most serious form of the disease. It can affect nearly the entire body with a widespread, fiery red rash that may itch or burn intensely. This type of psoriasis disrupts the body’s ability to regulate temperature and protect against infection, making it a potentially life-threatening condition. According to NICE clinical standards, this form of the condition requires immediate specialist dermatological assessment and often inpatient hospital treatment. 

Conclusion 

Psoriasis is a complex condition with various presentations, ranging from the common plaques found on joints to more specialised forms affecting skin folds or the nails. While most types are managed with topical treatments and routine care, certain forms like erythrodermic psoriasis require urgent medical intervention. Understanding which type of psoriasis is present is essential for effective long term management and symptom control. 

If you experience a sudden, widespread reddening of the skin accompanied by a high fever or severe pain, call 999 immediately. 

Authority Snapshot (E-E-A-T Block) 

This article outlines the different classifications of psoriasis to assist patients in identifying their symptoms based on clinical standards. It has been produced by the MyPatientAdvice Medical Writing/Research Team and reviewed by Dr. Rebecca Fernandez, a UK-trained physician with experience in internal medicine and emergency care. All content is strictly based on NHS and NICE guidance to ensure the highest level of accuracy and patient safety.