Types of Psoriasis

Plaque Psoriasis

Plaque psoriasis marks are lesions with red, raised scales. These raised areas are known in dermatology as plaques. In contrast to other inflammatory skin lesions, plaque psoriasis has well-defined borders.

A typical plaque rises 2-3 millimetres above the skin surface (epidermis), is scaly and shows a reddish appearance with well demarcated borders. The colour may vary depending on the skin type and the location of the lesion on the body.

The scales can be separated from the skin either with a sharp object or typically with the fingernails. When the lesion is scratched continuously the reddish colour of the scale changes and the surface becomes opaque. If the scales are detached from the plaque a thin membrane becomes visible, which represents the last keratinocyte layers of the lower epidermis (Stratus Spinosum).

Patients with plaque psoriasis suffer from psychological symptoms because scaling is frequent and is evident wherever they walk or on their clothes.

Specific locations of Plaque Psoriasis

Psoriasis on the scalp (Scalp Postriasis)

The most common area affected is the scalp. Generally speaking, the lesions are similar to those occurring on the rest of the body, but are more difficult to observe and examine as they are covered with hair. These lesions typically only sprout on the scalp where hair is growing and areas of the scalp with signs of baldness typically do not. The lesions may protrude up to 1 centimetre from the edge of the hair area and are the same as plaques on other parts of the body, although sometimes their reddish appearance takes on a yellowish cast.

Psoriasis intetriginosa

Intertriginous is a medical term used to define an area in two areas of the skin that may touch or rub together. Examples of intertriginous areas are the armpit of the arm, the anogenital region, nostrils, skin folds of the breasts and between the fingers.

Unlike other plaque psoriasis lesions, these lesions change their morphology where the scales instead of being silvery and dry look reddish and shiny as if they had wax on them.

Inverse Psoriasis

Describes lesions that are located on the inner side of the joints and is separated from other lesions because it can be confused with Atopic Dermatitis. The lesions typically produce small to medium-sized scales.

Palmoplantar Psoriasis

This is one of the most difficult because of its psychological effects on the patient, as the hands in particular are not covered by clothing and most activities require the use of them, making it impossible to do many jobs due to people's rejection. The lesions are similar to those in other areas of the skin, but more difficult to treat due to the thickness of the epidermis.

Kobner effect

This term is used when psoriasis lesions sprout on areas of skin that have previously suffered physical trauma. A week or two after the trauma, skin that was not necessarily involved in the trauma will sprout psoriasis and the shape of the psoriasis lesion will be similar to that of the trauma. In fact, Henrich Kobner of Berlin, Germany, described a horse-driving patient who was bitten by a horse on his upper arm and two weeks later developed psoriasis lesions in the shape of the bite.

Psoriasis Guttate

Psoriasis guttate is discussed as a specific manifestation of psoriasis and not as a variant of plaque psoriasis. It typically occurs in children, young adults and often as the first manifestation of psoriasis.

It manifests itself suddenly as small pimples and plaques measuring from a few millimetres to 1 to 2 cm in diameter. It can occur all over the body and does not cause as much scaling as plaque psoriasis.

In addition to the skin symptoms described above, some patients have symptoms of fever and fatigue.

There are some skin diseases that are confused with Psoriasis Guttate such as Psoriasis Rosea which occurs at the same age as Psoriasis Guttate. Patients also develop reddish, scaly lesions several centimetres in diameter known as the primary medallion. This does not exist in Psoriasis Guttate. The lesions of Psoriasis Rosea are larger than those of Psoriasis Guttate. It is also rare for Psoriasis Rosea to occur on the face.

Pustular Psoriasis

These types of pustular lesions are less common than erythroderma-type lesions (reddening of the skin). Guttate or plaque psoriasis lesions typically anticipate the appearance of pustular lesions.

Factors that trigger Pustular Psoriasis

Progesterone (Pregnancy)

At the end of the second part of pregnancy this hormone increases and it has been described in studies such as that of (Murfy & Stoleman, 1974) that after administering this hormone pustular psoriasis is triggered.

Corticosteroid therapy

In a study by (Brian & Baker, 1968) 37 out of 104 patients studied with pustular psoriasis had received corticosteroid treatment.

Irritants such as pyrogallol or dithranol or an overdose of ultraviolet rays also trigger Pustular Psoriasis.

Infections - especially of the respiratory tract

Eruption patterns of pustular psoriasis

Pattern - is defined as a repetition or recurrence of certain characteristics.

Zumbush pattern - Characterised by the abrupt eruption of erythema and pustules. During this phase the skin is very painful, the patient feels ill and sometimes feverish. After several days or weeks, the pustules disappear and a desquamation proceeds. The skin typically clears and the desquamation ceases.

Annular (Circle or round)pattern - the rash is characterised by round lesions that are more or less spread out. The lesions consist of erythema (redness) and scaling with pustules at the periphery. The lesions gradually grow and may last for weeks, months or even years. Sometimes they can grow within hours and last for weeks (Lapiere, 1959).

Exanthematous type pattern (Exanthema = skin rash) - An acute rash of pustules and erythema. The rash sometimes starts on the palms of the hands and soles of the feet, and then spreads abruptly over the rest of the body.

The term pustular psoriasis encompasses several subtypes of pustular psoriasis:

Generalised Pustular Psoriasis (GPP)

Pustular Psoriasis during Pregnancy (PPPP)
Annular (circle or round) psoriasis (EACP)
Psoriasis vulgaris pustulosa
Pustular Palmoplantar Psoriasis (PPP)
Psoriasis Hallopeau

GPP - Generalised Pustular Pustular Psoriasis

It is also known as the Zumbusch pattern as Leo Ritter von Zumbusch was the first to describe this type of lesion in 1910. This type of lesion is known to be the most severe of all types of psoriasis including possible life-threatening effects.

Inflammation is more pronounced than plaque psoriasis and the following triggers of plaque psoriasis have been reported:

Respiratory tract infections, especially streptococcal and vaccine-associated infections
Chemical, physical and mechanical factors, e.g. solar irradiation or irritating topical substances.
Hypocalcaemia
Hormonal changes, pregnancy, oral contraceptives, stopping corticosteroid use
Stress due to strong emotions or complicated situations such as divorce, accidents, loss of loved ones, financial situations, etc.
Medications such as lithium, beta-blockers, anti-malarials, ACE inhibitors such as ramipril or topical indomethacin.

Clinical picture

Pustular psoriasis is characterised by a sudden outbreak of erythema with a rapid spread of small pustules. These pustules may appear within a few hours, but may last for several weeks. Often these pustules coalesce and form pus lesions.

When the pustules rupture and dry, the skin sloughs off, resulting in skin erosions that can become infected. This disease sometimes includes several cycles of eruption, pus, rupture, drying and sloughing of the skin. While the lesions show desquamation, new lesions with pustules may erupt and an expansion of these lesions may eventually create erythema (redness of the skin). The face is not normally affected by pustular psoriasis but nails, palms of the hands and soles of the feet may be affected.

GPPP - Generalised Pustular Psoriasis during Pregnancy

GPPP has been accepted as a variant of annular pustular psoriasis described below and occurs during pregnancy due to hormonal disruption.

Psoriasis Annulare or EACP - Erythema Annulare of the Centrifugal Pustular type)

This type of psoriasis was reported by Lapiere in 1959, and later Huriez and Degos introduced the term (EACP). This is a rare variant of psoriasis that suddenly flares up in patients with no history of psoriasis such as patients with plaque psoriasis or pustular psoriasis.

Clinical picture

Annular (circle or round) psoriasis is characterised by erythema (redness) or discrete ring or snake-shaped plaques (curved lines). The lesions are covered with pustules and the course of these lesions causes it to arise suddenly and recede in the same way. This can happen over weeks or several months.

Psoriasis Vulgaris with postulation

This term is used when pre-existing psoriasis vulgaris develops pustules on the psoriasis plaques.

Palmoplantar psoriasis pustolosa

This psoriasis, known as PPP, was first described in 1888 by Crocker as Dermatitis repens and was associated with psoriasis until 1930.

Clinical picture

PPP manifests in patients with no history of psoriasis. Women are more affected than men by a ratio of 9 to 1, showing first symptoms in the 3rd and 4th decade. Interestingly, up to 95% of patients are former or current smokers.

Initially, small yellow pustules sprout from side to side of old, dry pustules. Some patients have the lesions on only one area of the palms or soles of the feet.

Psoriasis Hallopeau

The name comes from the French dermatologist François Henri Hellopeau (1842-1919). It has been classified as a subtype of plaque psoriasis, although it remains controversial.

Clinical picture

Lesions typically start from an area of trauma or infection, often involving one or two fingers or toes. Pustules (reddish) are generated in the erythema; when the pustule matures, pus is generated.