Psoriasis Explained Clearly – Including Types and Treatment

Introduction to Psoriasis

[00:00] Psoriasis is a chronic inflammatory condition affecting primarily the skin, classically characterized by well-defined red scaly plaques. The name itself comes from Greek and means itching

[00:20] disease. In normal circumstances, cells in the outermost layer of the skin, the epidermis, will gradually replicate and migrate to the skin surface. These cells are keratinocytes that differentiate as they migrate through the layers of the epidermis, from the

Pathophysiology of Psoriasis

[00:40] stratum basale where they are produced to the stratum corneum that is made up of mostly dead keratinocytes and keratin. In psoriasis however, sustained inflammation leads to increased mitotic activity of the keratinocytes, meaning they divide faster than normal

[01:00] giving uncontrolled proliferation as well as dysfunctional differentiation. The result is the formation of the plaque's characteristic of psoriasis, which feature epidermal hyperplasia, inflammatory infiltrates, and increased vascularity.

Genetics and Triggers of Psoriasis

[01:20] This is thought to be the result of an immune-mediated process present across the dermis and epidermis that leads to a cascade of inflammatory mediators. Specifically, interleukin 13 and 17 have been found in increased levels in patients with psoriasis.

[01:40] and are thought to play a significant role, as well as TNF alpha. Overall, it's therefore thought that external insults in genetically susceptible individuals trigger the immune reaction and development of psoriasis. Heritability is estimated to be

[02:00] between 60 and 90%, and a group of areas of the genome associated with psoriasis have been identified, called psoriasis susceptibility, SALT. One is located close to the major histocompatibility complex on chromosome 6,

[02:20] with the HLA-CW-0602 allele being closely correlated with psoriasis before the age of 40 and a positive family history, although the exact mechanism is not currently understood. Triggering or aggravating factors associated with psoriasis,

[02:40] include drugs with beta blockers in 20% of people with psoriasis and lithium in 50%, as well as others like antimalarial drugs, nonsteroidal anti-inflammatories, ACE inhibitors and antibiotics like amoxicillin. Trauma or injury can also induce

[03:00] or worsen lesions and this is known as the kirbner phenomenon. Infection is another, primarily streptococcal infections like strep throat, but HIV is also another example. Stress, smoking, alcohol and obesity are also potential triggers or aggravates

Epidemiology and Common Characteristics

[03:20] It affects roughly 3% of the US population and affects males and females roughly equally. There are two peaks of typical onset, between 15 and 25 years and between 50 and 60 years. Around 1 in 3 people with psoriasis also have an effect on their blood pressure.

[03:40] affected family member. There are several different subtypes, with plaxoriasis being the most common in all ethnicities, making up around 90%. It features well-defined red, scaly plaques, often with a white or silver colour. If this is scraped away,

[04:00] It can reveal pinpoint bleeding, where dilated dermal capillaries are exposed, called auspits sign. They can be present anywhere, however the most commonly affected areas are the scalp and extensor surfaces of elbows and knees. Non-cocasins tend to have more extensors.

Types of Psoriasis and Clinical Features

[04:20] intensive involvement, and plaques can appear more purple in darker skin colours. Itching is present in 60 to 90% of patients and can vary from mild to severe, and over time, scratching can lead to lichenification and thickening of the skin. Pigment changes either

[04:40] Hypo or hyperpigmentation can be left behind as plaques clear. Flextrous psoriasis, as the name suggests, is more commonly found in flextrous and folds of skin, such as the groin, armpits or beneath the breasts, and commonly has a moist, shiny appearance

[05:00] rather than silver scales. This is also called inverse psoriasis. Gut-tate psoriasis often follows a streptococcal upper respiratory tract infection, mostly in children and young adults, and features widespread, fine, scaly lesions that resemble water drops.

[05:20] which is where the name comes from. These are mostly on the trunk, arms and legs. Pustular psoriasis features development of yellow or brown pustules beneath the skin, mostly on the hands and feet. However, it can be an acute generalized condition with fluid

[05:40] like symptoms, which is severe and requires hospital treatment as the ability to regulate temperature is lost. The pustules are sterile and non-infectious. Another type is erythrodermic psoriasis, characterized by generalized reddening with fine scales affecting between 90

[06:00] and 100% of the body surface. This can be painful and like generalized postulaceritis also feature flu-like symptoms. And similarly is a medical emergency, due to the loss of thermoregulation and risk of hypovolemia. In around one third of cases of people with other

[06:20] forms of psoriasis. There can be nail or joint involvement. The joint involvement can be destructive and is most commonly in the distal interphalangeal joints of fingers and toes, but can involve any joint and can vary in its symmetry. Nail psoriasis features pitting, thickening,

Psoriasis and Systemic Disease Links

[06:40] discoloration without separation from the nail plate and may appear like a fungal infection. There is an association between psoriasis and other diseases, with psoriasis, obesity and type 2 diabetes being correlated, thought to be due to genetic influence and chronic inflammation.

[07:00] and this is independent of age, sex and smoking history. The interleukin-23 T-helper cell 17 pathway is relevant in psoriasis, but is also relevant in atherosclerosis. Overall, these mean a higher risk of metabolic syndrome and cardiovascular

[07:20] disease, with psoriasis itself being considered an independent risk factor for cardiovascular disease. Diagnosis is a clinical one, meaning it can be diagnosed on the history and clinical exam alone. If there is uncertainty, a skin biopsy may be taken. It is generally

Diagnosis and Severity Assessment

[07:40] considered mild if less than 10% of the body surface is involved and scoring systems exist, such as the psoriasis area and severity index, but these are generally used more in research. If diagnosed, then a cardiovascular risk workup should also be done. That includes BMI

[08:00] high, blood pressure, bloods such as HBA1c, lipids, liver function and uric acid, and an ECG. In terms of treatment, there are general recommendations that include weight management, cessation of smoking and alcohol consumption limits, and a wide range of

General Management Recommendations

[08:20] If therapies exist depending on the type and severity of psoriasis, topical agents can broadly be divided into four categories, emollients, antiproliferative, anti-inflammatory, and descaling agents. Emollients are moisturising agents. They enhance skin hydration and

[08:40] help correct the dryness seen in psoriasis. They also aid the barrier function of the skin and can soothe itching. Many preparations are available, ranging from heavier to lighter creams with more or less lipid content, and so should be individualised to the patient's needs and preference. Antiproliferative

[09:00] include Vitamin D analogues like calciputriole or calcitriole, as well as coal tar. These induce normal keratinocyte proliferation and differentiation. Shampoo formulations are available that can be used in scalp psoriasis. Anti-inflammatories are primarily

[09:20] topical steroids, with mild to potent agents being preferred in psoriasis. Generally, lower potencies are used on areas such as the face and genitals, as well as any area of skin in contact with skin, such as the axilla or groin. Hydrocortisone is an example of a mild steroid

Topical Treatments for Psoriasis

[09:40] Clabetazone butyrate, also known as humivate, for moderate, and beta-methazone for lyrate, or betnevate, for potent. They are ideally only used for up to 3 weeks before having a steroid break, for 1 to 2 weeks, in order to reduce the unwanted effects, like skin atrophy and tightness.

[10:00] where increasing doses are needed for the same effect. Steroid sparing therapies include calcineurin inhibitors like tachrolimus, available topically, roflumilast, which is a topical phosphodiesterase IV inhibitor, and tazarotene as a topical retinoid.

[10:20] versions of antiproliferative and anti-inflammatory agents are available too, such as Dovobet, that includes beta-methazone, dipropionate and calciputriol. The fourth is descaling agents. These are keratinolytic and help soften the scales, an example being salicylic acid. This is particularly

[10:40] useful on the scalp, where the scale can be very thick. Phototherapy using ultraviolet light is another option, with UVB light reducing DNA synthesis and can cause mild immunosuppression. And Soralen with UVA or PUVA is a form of photochemistry

Advanced Therapies and Systemic Treatments

[11:00] that has an antiprolifative effect. There is a risk of burns if exposure is too high and it is used more in extensive cases, but its use is decreasing due to the availability of systemic therapies. These systemic therapies can include agents such as methotrexate, cyclosporine,

[11:20] or microphenolate mofetil and there are biological therapies available in the form of monoclonal antibodies, such as TNF inhibitors like Itanosept or Infleximab, IL-23 inhibitors like Tildrachizumab and IL-17 inhibitors like Secukinamab.

[11:40] Generally, topical agents are used in mild plaque or flexural psoriasis, with phototherapy or systemic therapies being added in moderate or severe cases, including erythodermic, pustular, and nail psoriasis or seritic arthritis. Scalp psoriasis is more difficult to treat because they

[12:00] hair can block topical agent application, as well as shielding from UV light. Some ways this is worked around is by application of agents with a toothbrush and use of a shower cap overnight. Gut-ate psoriasis usually responds well with treatment of the underlying infection if indicated

[12:20] and then topical or systemic therapy afterwards.