Types of Psoriasis
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- Published on Friday, 02 December 2011 04:19
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Plaque Psoriasis
Plaque psoriasis is the most prevalent form of psoriasis representing 80% of cases, while guttate, erythrodermic, and pustular account for 10%, 3%, and 3% of patients respectively.
Doctors refer to it as erythemato-squamous, meaning red and scaly; lesions take the form of round or oval plaques, which are red and clearly demarcated and covered by numerous superficial dry scales.
The scale is a silvery color and normally covers the entire red patch, from which it flakes off in abundance.
Plaques can vary in size and number and scratching leads to bleeding. Their color may vary in intensity, and they are often more red towards the edge of a plaque than at the center. The plaques can be thin or thick. They are often found symmetrically on the outer arms and legs, especially on both elbows and/or both knees, but any part of the body can be affected.
The condition can appear on various parts of the body and lesions vary depending on the body part affected. It is mostly found on the elbows, knees, back and scalp. However, it can also appear on other parts of the body, such as the face, hands, feet, nails, skin folds and mucous membranes.
Plaque psoriasis is accompanied by itching in 60% to 70% of cases. It does not cause itching all the time, but this is a problem for some people.
Guttate Psoriasis
Diagnosis of typical forms of psoriasis is straightforward, but it is more difficult to identify atypical forms; these can be distinguished by the morphological features of the eruption.
Small, round, scattered lesions are typical of guttate psoriasis or psoriasis “guttata”. This type of psoriasis presents as small red scaly dots (instead of thick plaques), which look like drops of water sprinkled over the body. These are mostly seen in young patients (children or adolescents).
Its onset is often severe and usually follows a streptococcal throat infection (such as rhinopharyngitis, pharyngitis or tonsillitis). This type of psoriasis tends to go into spontaneous remission after several weeks. It can reappear either in the same form, or as classical psoriasis.
Psoriatic arthritis
In most cases, several years after psoriasis has broken out, patients may be affected by Psoriatic arthritis.
This is an inflammatory, chronic arthritis with varied degree of joint manifestations. It is treated separately from cutaneous lesions and the course of the disease is unpredictable.
Psoriatic arthritis belongs to the spondyloarthropathies group and it can be distinguished from other types of inflammatory arthritis primarily based on the accompanying skin condition.
The appearance of psoriatic arthritis is like most psoriasis episodic, punctuated with periods of remission of varying length. It involves peripheral joints (the hips, shoulders, hands and feet) in 70% of cases, and sometimes the spinal column (known as the axial form of psoriatic arthritis). Psoriatic arthritis can also affect the entheses. i.e. the regions where the tendons are attached to the bone, which may explain pain in the heels etc.
The condition most commonly appears between the ages of 30 and 50 and affects men and women equally. However, men most often present with axial forms of the condition, whereas women tend to suffer more from peripheral forms. The exact number of people suffering from psoriatic arthritis is not known, but it is estimated that around 30% of the psoriatic patients are affected.
Healthy joints contain cartilage at the ends of the bones which serve as cushions when the joint moves. The joint cavity is lined with a vascular membrane, known as the synovial membrane. It supplies the cartilage and bone extremities with essential nutrients. The synovial membrane is reinforced by a more rigid structure, called the articular capsule. Psoriatic arthritis affects the areas where the bone extremities enter this capsule and, more specifically, the areas where the tendon is attached to the bone (i.e. the entheses).
As the vessels in these areas increase in volume, a process known as vasodilatation, there is an increased supply of fluid, leading to oedema and swelling. When oedema is formed, white blood cells migrate to the area. The white blood cells in combination with the oedema cause further inflammation and pain.
No-one knows what causes this condition, but genetics play an important role. Children whose parents suffer from psoriatic arthritis are three times more likely to develop it. The identical twin of an affected patient has a 75% chance of suffering from it. Read more about causes of psoriasis in general.
Nummular Psoriasis
In contrast to the drop-like patches of guttate psoriasis, nummular psoriasis is characterized by round plaques which are a few centimeters in diameter (disc-shaped psoriatic lesions). Their size is more or less the same as a coin. This is a rare form of Psoriasis, also known as "Psoriasis discoidea" and frequently confused with Chronic Nummular eczematous dermatitis (a form of highly pruritic eczema).
Erythrodermic Psoriasis
In erythrodermic psoriasis, there is marked, universal edema with variable desquamation (skin shedding).
There may be natural progression of the disease or more frequently, after attempted therapies, interruption of systemic corticoid therapy, or in patients with AIDS.
There is clear predominance of erythema (redness of the skin due to congestion of the capillaries) over desquamation.
There may be hyper or hypothermia and in long-term cases, there may be reduction of cardiac output and impairment of liver and renal function. The eminent risk of cardiovascular shock and septic shock transform these patients into extremely severe cases, requiring immediate hospitalization and therapeutic intervention associated with support measures.
When compared to adults, erythrodermic psoriasis and psoriatic arthritis are less frequent clinical presentations in children.
Pustular Psoriasis
Pustular psoriasis is an uncommon form of psoriasis. (Around 10%) People with pustular psoriasis have clearly defined, raised bumps on the skin that are filled with pus (pustules). The skin under and around these bumps is red. Large portions of your skin may redden.
The skin changes you may notice before, during, or after an episode of pustular psoriasis may be similar to those of regular psoriasis. People with the usual skin symptoms of psoriasis have patches of raised skin with scales. These flare-ups sometimes occur when a person ends Prednisone or corticosteroid use, gets an infection, or becomes pregnant.
Pustular psoriasis is classified into one of several types, depending on your symptoms. Your symptoms may be sudden and severe (acute), long term (chronic), or somewhere in between (subacute). The generalized type affects your whole body with more than just skin symptoms.
A generalized type with acute symptoms, fever, and a toxic reaction in your tissues is called the von Zumbusch type. A ring-shaped (annular, or circinate) type has also been described. It is usually subacute or chronic, and people with this type do not usually have symptoms aside from the skin symptoms. If you also have fever, chills, or dehydration, seek medical attention immediately.
Pustules may be localized to the palms and soles (palmoplantar pustulosis). The least common type is the juvenile, or infantile type, which occurs in children.
Pustular psoriasis is not common. In Japan, only about 7.46 people per 1,000,000 have pustular psoriasis. Pustular psoriasis affects all races. In adults, it affects men and women equally. In children, it affects boys somewhat more often than girls but it is rare.The average age of people with pustular psoriasis is 50 years. Children aged 2-10 years can be affected, but this is rare.
Some forms of psoriasis are more severe and particularly resistant to treatment. These are pustular psoriasis, erythrodermic psoriasis and psoriatic arthritis. These should receive very careful medical treatment, in collaboration with dermatologists.
To view pictures of the various type of psoriasis visit our gallery area.
Credits
eMedicineHealth, WebMd, Psorinfo.com, Gladman et al., Ann Rheum Dis, 2005
