GPP presents as pustules and plaques over a wide area of the body. It differs from the localized form of pustular psoriasis in that patients are often febrile and systemically ill.

However, the most prominent symptom, as described in the "Archives of Dermatology", is “sheeted, pinhead-sized, sterile, sub-corneal pustules”. The IPC roundtable adds that these pustules often occur either at the edges “of expanding, intensely inflammatory plaques” or “within erythrodermic skin.”

Von Zumbusch psoriasis is named after the German dermatologist Leo Ritter von Zumbusch (1874–1940), son of Kaspar von Zumbusch who described the first documented case of generalized pustular psoriasis in the early 1900s. See Case Report #1.

Sometimes all or any of GPP is referred to as von Zumbusch psoriasis, but in the literature it is often distinguished as one specific form of GPP.

Eugene M. Farber, MD and colleagues provide a description of von Zumbusch psoriasis in "Pustular Psoriasis", published in "Cutis". They describe the pattern as having “waves of widespread or universally fiery redness”. The affected areas are “painful and tender”. Small sub-corneal pustules form, with sizes originally between 1 and 10 mm in diameter. These pustules may merge to form “yellow-green lakes of pus”. The pustules dry out, and “Waves of scarlatiniform [resembling scarlet fever] peeling follow, removing the desiccating pustules”. In regards to the onset, the von Zumbusch form may “supervene on any previous pattern of psoriasis”. It also may or may not recur periodically.

Characteristics may vary according to the subtype of pustular psoriasis. For example, it can be localized, commonly to the hands and feet (localized pustular psoriasis), or generalized with widespread patches occurring randomly on any part of the body (generalized pustular psoriasis). However, all forms of pustular psoriasis share in common the presence of red and tender blotchy skin covered with pustules.

Pustular psoriasis can be localized, commonly to the hands and feet (palmoplantar pustulosis), or generalized with widespread patches occurring randomly on any part of the body. Acrodermatitis continua is a form of localized psoriasis limited to the fingers and toes that may spread to the hands and feet. Pustulosis palmaris et plantaris is another form of localized pustular psoriasis similar to acrodermatitis continua with pustules erupting from red, tender, scaly skin found on the palms of the hands and the soles of the feet.

Generalized pustular psoriasis (GPP) is also known as (von Zumbusch) acute generalized pustular psoriasis in acute cases, and as impetigo herpetiformis during pregnancy. GPP is a rare and severe form of psoriasis that may require hospitalization. This form of psoriasis is characterized by an acute onset of numerous pustules on top of tender red skin. This skin eruption is often accompanied by a fever, muscle aches, nausea, and an elevated white blood cell count. Annular pustular psoriasis (APP), a rare form of GPP, is the most common type seen during childhood. APP tends to occur in women more frequently than in men, and is usually less severe than other forms of generalized pustular psoriasis such as impetigo herpetiformis. This form of psoriasis is characterized by ring-shaped plaques with pustules around the edges and yellow crusting. APP most often affects the torso, neck, arms, and legs.

Typically guttate psoriasis erupts after a throat infection, or strep throat. Initially, when the throat infection has cleared up, the person can feel fine for several weeks before noticing the appearance of red spots. They appear small at first, like a dry red spot which is slightly itchy. When scratched or picked the top layer of dry skin is removed, leaving dry, red skin beneath with white, dry areas marking where flakes of dry skin stop and start. In the weeks that follow the spots can grow to as much as an inch in diameter. Some of the larger ones may form a pale area in the center which is slightly yellow.

Guttate psoriasis can occur on any part of the body, particularly the legs, arms, torso, eyelids, back, bottom, bikini-line and neck. The number of lesions can range from 5 to over 100. Generally the parts of the body most affected are seen on the arms, legs, back and torso.

Guttate psoriasis is characterized by numerous small, scaly, red or pink, droplet-like lesions (papules). These numerous spots of psoriasis appear over large areas of the body, primarily the trunk, but also the limbs and scalp. Guttate psoriasis is often triggered by a streptococcal infection, typically streptococcal pharyngitis. The reverse is not true.

The disease presents with the widespread formation of fluid-filled blisters that are thin walled and easily ruptured and the patient can be positive for Nikolsky's sign. Ritter's Disease of the Newborn is the most severe form of SSSS with similar signs and symptoms. SSSS often includes a widespread painful erythroderma, often involving the face, diaper, and other intertriginous areas. Extensive areas of desquamation might be present. Perioral crusting and fissuring are seen early in the course. Unlike toxic epidermal necrolysis, SSSS spares the mucous membranes. It is most common in children under 6 years, but can be seen in adults who are immunosuppressed or have renal failure.

Pustular psoriasis is classified into two major forms: localized and generalized pustular psoriasis. Within these two categories there are several variants:

Psoriasis in the mouth is very rare, in contrast to lichen planus, another common papulosquamous disorder that commonly involves both the skin and mouth. When psoriasis involves the oral mucosa (the lining of the mouth), it may be asymptomatic, but it may appear as white or grey-yellow plaques. Fissured tongue is the most common finding in those with oral psoriasis and has been reported to occur in 6.5–20% of people with psoriasis affecting the skin. The microscopic appearance of oral mucosa affected by geographic tongue (migratory stomatitis) is very similar to the appearance of psoriasis. However, modern studies have failed to demonstrate any link between the two conditions.

Erythroderma is generalized exfoliative dermatitis, which involves 90% or more of the patient's skin. The most common cause of erythroderma is exacerbation of an underlying skin disease, such as psoriasis, contact dermatitis, seborrheic dermatitis, lichen planus, pityriasis rubra pilaris or a drug reaction. Primary erythroderma is less frequent and is usually seen in cases of cutaneous T-cell lymphoma, in particular in Sézary's disease.

The most common causes of exfoliative dermatitis are best remembered by the mnemonic device ID-SCALP. The causes and their frequencies are as follows:

- Idiopathic - 30%

- Drug allergy - 28%

- Lymphoma and leukemia - 14%

- Atopic dermatitis - 10%

- Psoriasis - 8%

- Contact dermatitis - 3%

- Seborrheic dermatitis - 2%

Differential diagnosis in patients with erythroderma may be difficult.

AGEP is an acute febrile drug eruption characterized by numerous small, primarily non-follicular, sterile pustules, arising within large areas of red swollen skin.

The eruption follows a self-limiting course and will end before a week provided the causative agent (e.g. medication) is discarded. It is accompanied by fever, a high number of neutrophils and eosinophils in the blood, liver inflammation, and sometimes by facial swelling. The mortality rate is about 5% and the differential diagnosis includes Stevens–Johnson syndrome (SJS). Contrary to SJS, in AGEP, mucosa are not affected, which means that there are no blisters in the mouth or vagina.

The treatment is (1) stop the offending drug (antibiotics), (2) symptomatic (fever), and (3) for complications (hepatitis).

Patients with acute GPP experience the eruption of multiple isolated sterile pustules generalized over the body, recurrent fevers, fatigue, and laboratory abnormalities (elevated ESR, elevated CRP, combined with leukocytosis).

Dyshidrosis has been described as having the following characteristics:

- Itchiness of the palms or soles, followed the a sudden development of intensely itchy small blisters on the sides of the fingers, the palms or the feet.

- These blisters are often described as having a "tapioca pudding" appearance.

- After a few weeks, the small blisters eventually disappear as the top layer of skin falls off.

- These eruptions do not occur elsewhere on the body.

- The eruptions may be symmetrical.

Guttate psoriasis (also known as eruptive psoriasis) is a type of psoriasis that presents as small (0.5–1.5 cm in diameter) lesions over the upper trunk and proximal extremities; it is found frequently in young adults. The term "guttate" is used to describe the drop-like appearance of skin lesions. Guttate psoriasis is classically triggered by a bacterial infection, usually an upper respiratory tract infection.

Erythroderma (also known as "Exfoliative dermatitis," "Dermatitis exfoliativa") is an inflammatory skin disease with erythema and scaling that affects nearly the entire cutaneous surface.

In ICD-10, a distinction is made between "exfoliative dermatitis" at L26, and "erythroderma" at L53.9.

Kogoj's spongiform pustules can be observed via histopathology to confirm acute GPP.

Localized pustular psoriasis presents as two distinct conditions that must be considered separate from generalized psoriasis, and without systemic symptoms, these two distinct varieties being pustulosis palmaris et plantaris and acrodermatitis continua.

A rash is a change of the human skin which affects its color, appearance, or .

A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracked or blistered, swell, and may be painful.

The causes, and therefore treatments for rashes, vary widely. Diagnosis must take into account such things as the appearance of the rash, other symptoms, what the patient may have been exposed to, occupation, and occurrence in family members. Rash can last 5 to 20 days, the diagnosis may confirm any number of conditions.

The presence of a rash may aid diagnosis; associated signs and symptoms are diagnostic of certain diseases. For example, the rash in measles is an erythematous, morbilliform, maculopapular rash that begins a few days after the fever starts. It classically starts at the head, and spreads downwards.

The most common type of eruption is a morbilliform (resembling measles) or erythematous rash (approximately 90% of cases). Less commonly, the appearance may also be urticarial, papulosquamous, pustular, purpuric, bullous (with blisters) or lichenoid. Angioedema can also be drug-induced (most notably, by angiotensin converting enzyme inhibitors).

Erosive pustular dermatitis of the scalp (also known as "Erosive pustular dermatosis of the scalp") presents with pustules, erosions, and crusts on the scalp of primarily older Caucasean females, and on biopsy, has a lymphoplasmacytic infiltrate with or without foreign body giant cells and pilosebaceous atrophy.

Pustular bacterid is a skin condition characterized by a symmetric, grouped, vesicular or pustular eruption on the palms and soles marked by exacerbations and remissions over long periods of time.

Psoriatic nails are characterized by a translucent discolouration in the nail bed that resembles a drop of oil beneath the nail plate. Early signs that may accompany the "oil drop" include thickening of the lateral edges of the nail bed with or without resultant flattening or concavity of the nail; separation of the nail from the underlying nail bed, often in thin streaks from the tip-edge to the cuticle; sharp peaked "roof-ridge" raised lines from cuticle to tip; or separation of superficial layers of the nail followed by loss of patches of these superficial layers, leaving thin red nails beneath; or nail pitting–punctate changes along the nail plate surface.

Dyshidrosis, is a type of dermatitis, that is characterized by itchy blisters on the palms of the hands and bottoms of the feet. Blisters are generally one to two millimeters in size and heal over three weeks. However, they often recur. Redness is not usually present. Repeated attacks may result in fissures and skin thickening.

The cause is unknown. Triggers may include allergens, physical or mental stress, frequent hand washing, or metals. Diagnosis is typically based on what it looks like and the symptoms. Allergy testing and culture may be done to rule out other problems. Other conditions that produce similar symptoms include pustular psoriasis and scabies.

Avoiding triggers may be useful as may a barrier cream. Treatment is generally with steroid cream. High strength steroid creams may be required for the first week or two. Antihistamines may be used to help with the itch. If this is not effective steroid pills, tacrolimus, or psoralen plus ultraviolet A (PUVA) may be tried.

About 1 in 2,000 people are affected in Sweden. Males and females appear to be affected equally. It explains about one in five cases of hand dermatitis. The first description was in 1873. The name comes from the word "dyshidrotic," meaning "difficult sweating," as problems with sweating was once believed to be the cause.

Eosinophilic pustular folliculitis of infancy (also known as "Eosinophilic pustular folliculitis in infancy," "Infantile eosinophilic pustular folliculitis," and "Neonatal eosinophilic pustular folliculitis") is a cutaneous condition characterized by recurrent pruritic crops of follicular vesiculopustular lesions.

Dermatographic urticaria manifests as an allergic-like reaction, in general a warm red wheal (welt) to appear on the skin. It can often be confused with an allergic reaction to the object causing the scratch, when in fact it is the act of being scratched that causes a wheal to appear. These wheals are a subset of [urticaria] (hives) that appear within minutes, in some cases accompanied by itching. The first outbreak of urticaria can lead to others on body parts not directly stimulated, scraped, or scratched. In a normal case, the swelling will decrease with no treatment within 15–30 minutes, but, in extreme cases, itchy red welts may last anywhere from a few hours to days.