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.

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.”

Although a clear understanding of the various skin lesions in IgG4-related disease is a work in progress, skin lesions have been classified into subtypes based on documented cases:

- Angiolymphoid hyperplasia with eosinophilia (or lesions that mimic it) and cutaneous pseudolymphoma

- Cutaneous plasmacytosis

- Eyelid swelling (as part of Mikulicz's disease)

- Psoriasis-like eruptions

- Unspecified maculopapular or erythematous eruptions

- Hypergammaglobulinemic purpura and urticarial vasculitis

- Impaired blood supply to fingers or toes, leading to Raynaud's phenomenon or gangrene

Note:

In addition, Wells syndrome has also been reported in a case of IgG4-related disease.

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.

Psoriasis can affect the nails and produces a variety of changes in the appearance of finger and toe nails. Nail psoriasis occurs in 40–45% of people with psoriasis affecting the skin and has a lifetime incidence of 80–90% in those with psoriatic arthritis. These changes include pitting of the nails (pinhead-sized depressions in the nail is seen in 70% with nail psoriasis), whitening of the nail, small areas of bleeding from capillaries under the nail, yellow-reddish discoloration of the nails known as the oil drop or salmon spot, thickening of the skin under the nail (subungual hyperkeratosis), loosening and separation of the nail (onycholysis), and crumbling of the nail.

Psoriatic arthritis is a form of chronic inflammatory arthritis that has a highly variable clinical presentation and frequently occurs in association with skin and nail psoriasis. It typically involves painful inflammation of the joints and surrounding connective tissue and can occur in any joint, but most commonly affects the joints of the fingers and toes. This can result in a sausage-shaped swelling of the fingers and toes known as dactylitis. Psoriatic arthritis can also affect the hips, knees, spine (spondylitis), and sacroiliac joint (sacroiliitis). About 30% of individuals with psoriasis will develop psoriatic arthritis. Skin manifestations of psoriasis tend to occur before arthritic manifestations in about 75% of cases.

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.

The following are conditions commonly associated with pyoderma gangrenosum:

- Inflammatory bowel disease:

- Ulcerative colitis

- Crohn's disease

- Arthritides:

- Rheumatoid arthritis

- Seronegative arthritis

- Hematological disease:

- Myelocytic leukemia

- Hairy cell leukemia

- Myelofibrosis

- Myeloid metaplasia

- Monoclonal gammopathy

- Autoinflammatory disease:

- Pyogenic sterile arthritis, pyoderma gangrenosum, and acne syndrome (PAPA syndrome)

- Granulomatosis with polyangiitis

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.

Psoriatic onychodystrophy or psoriatic nails is a nail disease. It is common in those suffering from psoriasis, with reported incidences varying from 10% to 78%. Elderly patients and those with psoriatic arthritis are more likely to have psoriatic nails.

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.

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

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.

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.

The term pustular psoriasis is used for a heterogeneous group of diseases that share pustular skin characteristics.

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).

There are two main types of pyoderma gangrenosum:

- the 'typical' ulcerative form, which occurs in the legs

- an 'atypical' form that is more superficial and occurs in the hands and other parts of the body

Other variations are:

- Peristomal pyoderma gangrenosum comprises 15% of all cases of pyoderma

- Bullous pyoderma gangrenosum

- Pustular pyoderma gangrenosum

- pyoderma gangrenosum

The only sign of vitiligo is the presence of pale patchy areas of depigmented skin which tend to occur on the extremities. The patches are initially small, but often grow and change shape. When skin lesions occur, they are most prominent on the face, hands and wrists. The loss of skin pigmentation is particularly noticeable around body orifices, such as the mouth, eyes, nostrils, genitalia and umbilicus. Some lesions have increased skin pigment around the edges. Those affected by vitiligo who are stigmatized for their condition may experience depression and similar mood disorders.

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.

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.

ILVEN is a condition that normally only affects one side of the body (unilateral). Usually the left side of patients is affected. The condition is persistent and forms along characteristic lines. It usually appears on an extremity in infancy or childhood. Altman and Mehregan described six characteristic features of ILVEN: (1) early age of onset, (2) predominance in females (4:1 female-male ratio), (3) frequent involvement of the left leg, (4) pruritus, or "itchiness" (5) marked refractoriness to therapy, and (6) a distinctive psoriasiform and inflammatory histologic appearance.

von Zumbusch (acute) generalized pustular psoriasis, (acute GPP) is the most severe form of generalized pustular psoriasis, and can be associated with life-threatening complications.

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.

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.

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.