Pustular Psoriasis

Updated: Jan 26, 2017
  • Author: Annie O Morrison, MD; Chief Editor: Dirk M Elston, MD  more...
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Pustular psoriasis is an uncommon form of psoriasis consisting of widespread pustules on an erythematous background, as shown in the image below.

Note the clearly defined, raised bumps on the skin Note the clearly defined, raised bumps on the skin that are filled with pus (pustules). The skin under and around these bumps is reddish. Courtesy of Hon Pak, MD.

See Psoriasis: Manifestations, Management Options, and Mimics, a Critical Images slideshow, to help recognize the major psoriasis subtypes and distinguish them from other skin lesions.

Pustular psoriasis may result in erythroderma. Cutaneous lesions characteristic of psoriasis vulgaris can be present before, during, or after an acute pustular episode.

Types of pustular psoriasis

The acute generalized type is also termed von Zumbusch variant. This form of pustular psoriasis is accompanied by fever and toxicity, and it may be fatal if proper supportive measures are not taken during the acute phase.

The annular (or circinate) type is also known as subacute generalized pustular psoriasis. It tends to run a subacute or chronic course with fewer systemic manifestations. A disproportionately high number of cases are found in the pediatric population. [1]

A juvenile or infantile type of pustular psoriasis has been described, but it is the least common form.

Additionally, several disease entities are considered, by some, to be variants of pustular psoriasis. These include the following:

  • Pregnancy-associated impetigo herpetiformis: Occurring predominately in the third trimester, this is a variant of acute pustular psoriasis that carries an increased risk of subsequent stillbirth or fetal abnormalities. [2]

  • Acrodermatitis continua of Hallopeau: Characterized by pustular eruptions of the tips of fingers and toes, cases are generally refractory to treatment. Subsets of these cases are considered variants of pustular psoriasis, particularly since they are indistinguishable histologically and in early clinical presentation. [3]

  • Sneddon-Wilkinson syndrome or subcorneal pustular dermatosis (SCPD): The disease follows a relapsing and remitting course that may develop into generalized pustular psoriasis. Occurring predominately in patients middle-aged or older, SCPD is associated with underlying malignancies (most commonly multiple myeloma and IgA monoclonal gammopathy) and pyoderma gangrenosum. [4]

  • Acute generalized exanthematous pustulosis (AGEP): Characterized by a widespread rash evolving into pustules, AGEP is associated with a prescribed drug in over 90% of cases. A minority of patients develop systemic involvement, most commonly hepatic, renal, and pulmonary systems. AGEP is associated with IL36RN mutations similar to those found in pustular psoriasis, palmoplantar pustulosis, and acrodermatitis continua of Hallopeau, which is not surprising given the similarities in clinical and immunologic features of these diseases. Taken together, some consider AGEP  a drug-induced form of pustular psoriasis. [5]

For patient education information, see the Skin Conditions & Beauty Center, as well as Psoriasis, What Is Psoriasis?, Types of Psoriasis, Plaque Psoriasis, and Psoriasis Medications.


Etiology of Pustular Psoriasis

Enhanced polymorphonuclear leukocyte (PMNL) chemotaxis is much more pronounced in pustular psoriasis than in psoriasis vulgaris. [6] This observation has been attributed to either an intrinsic PMNL defect or to the presence of chemoattractants in the psoriatic epidermis. Although the principal stimulus that triggers the phenomenon of massive PMNL migration from the vasculature to the epidermis is unknown, several new pathways involved directly and indirectly with neutrophil chemotaxis have been the topic of recent investigations.

The interleukin (IL)‒36 receptors are expressed constitutively on dermal dendrocytes, CD4+ T cells, and macrophages and, when activated, promote maturation of monocyte-derived dermal dendrocytes and inductions of cytokines, including IL-1, IL-6, IL-23, tumor necrosis factor-alpha (TNF-a) , and interferon-gamma (INF-g), which promote neutrophil migration. [7]

A subset of IL-23‒responsive CD4+ T-cells, identified as Th17 cells, induce IL-17 and IL-22, which, in turn, induce production of IL-6, IL-8, and CXCL5, which promote differentiation, activation, and migration of neutrophils and provide a positive feedback loop for Th17 cell differentiation. Significantly increased levels of IL-17 have been identified in lesional skin of pustular psoriasis versus nonlesional skin of the same patients. [7]

IL-6 signaling has gained recent attention for its role in the pathogenicity of pustular psoriasis. The IL-6-receptor subunit functions as both a membrane-bound receptor and a soluble receptor. This dual functionality separates it from all other known cytokine receptors that function only as membrane-bound forms. The IL-6/IL-6R complex, together with the ubiquitously expressed gp130, activate the JAK/STAT kinase and the RAS/MEK/ERK/MAPK kinase pathways, which ultimately augment nuclear gene expression. The downstream effects of IL-6 include synthesis of acute phase reactants, B-cell maturation, T-cell differentiation, positive influence on Th17 cell development, maturation neutrophils from myeloid progenitors, increased expression of ICAM-1 and other endothelial adhesion molecules that enhance neutrophil migration, and release of proinflammatory cytokines, such as IL-23 and IL-17, to further promote the Th17 positive feedback loop. [7]

Electron microscopic studies have shown the presence of basal keratinocyte herniations in lesions of pustular psoriasis. These are cytoplasmic processes from basal keratinocytes that protrude into the dermis through gaps in the basal lamina. These herniations are mostly clustered over collections of neutrophils in the dermis. This finding suggests an increased production of neutrophilic proteolytic enzymes in the dermis of pustular psoriasis patients.

Immunohistochemical methods have determined the involvement of some of these proteases and their inhibitors in the development of pustules.

Elastase is a proteolytic enzyme released by PMNLs during the process of extravasation and migration through the dermoepidermal junction. One study found an epidermal elastase inhibitor (skin-derived antileukoproteinase) expressed in psoriatic skin prior to the influx of PMNLs, which disappeared when the composition of the infiltrate changed. This finding was not confirmed by other studies.

Additional studies investigating other potential mechanisms have shown decreased natural killer cell activity in generalized pustular psoriasis. An increased incidence of HLA-B27 also has been found among patients with pustular psoriasis. This haplotype is seen in psoriasis patients with peripheral arthritis, as well as in patients with ankylosing spondylitis and reactive arthritis.

Homozygous, compound heterozygous, and single heterozygous missense mutations in a gene (IL36RN) that encodes a soluble anti-inflammatory cytokine, an IL-36‒receptor antagonist, have been associated with autosomal recessive inherited and sporadic generalized pustular psoriasis, AGEP, acrodermatitis continua of Hallopeau, and palmoplantar pustulosis. [5, 8, 9] The presence of these mutations is associated with unopposed release of inflammatory cytokines, including IL-6, IL-8, IL-1a, IL-1b, TNF-a, and INF-g, which promote neutrophil activation and migration. [7]

Risk factors

The following factors can reportedly trigger an eruption of pustular psoriasis:

  • Withdrawal of systemic steroids, [10] potent topical steroids, [11] or cyclosporine [12]

  • Drugs, including salicylates, iodine, lithium, phenylbutazone, oxyphenbutazone, trazodone, penicillin, hydroxychloroquine, calcipotriol, interferon-alpha, recombinant interferon-beta injection, [13]  terbinafine, [14] and bCG vaccination [15]

  • Strong, irritating topical medications, including tar, anthralin, steroids under occlusion, and zinc pyrithione in shampoo

  • Cutaneous infections (eg, Staphylococcus aureus, Streptococcus epidermidis) [16]

  • Sunlight or phototherapy

  • Cholestatic jaundice

  • Hypocalcemia

  • Idiopathic in many patients


Epidemiology of Pustular Psoriasis

Prevalence of pustular psoriasis

Pustular psoriasis is uncommon in the United States. The prevalence of pustular psoriasis in Japan is 7.46 cases per 1 million people.

Race predilection

Pustular psoriasis affects all races.

Sex predilection

The male-to-female ratio for pustular psoriasis is 1:1 in the United States. Globally, a female predominance has been reported. [17, 18] The female-to-male ratio is 3:2 in children.

Age predilection

The average age among adult patients with pustular psoriasis is reported between 48 and 50 years. [17] The average age of onset of acute generalized pustular psoriasis is 41 years. [17]

Children aged 6 weeks to 10 years can be affected, though rarely. One case described generalized pustular psoriasis in a 6-week-old infant. [19] The mean age of onset for annular pustular psoriasis in pediatric populations is 6 years. [1]


Patient History

In generalized pustular psoriasis, the skin initially becomes fiery red and tender. Patients may have a preceding history of psoriasis, although this is not a requirement. [11] Constitutional signs and symptoms include headache, fever, chills, arthralgia, malaise, anorexia, and nausea. Within hours, clusters of nonfollicular, superficial, 2- to 3-mm pustules may appear in a diffuse pattern.

Flexural and anogenital areas are most commonly involved in pustular psoriasis. Less often, facial lesions occur. Pustules can appear on the tongue and develop subungually, resulting in dysphagia and nail shedding, respectively. [20] Pustules coalesce within 1 day to form lakes of pus that dry and desquamate in sheets, leaving behind a smooth, erythematous surface on which new crops of pustules may recur.

Episodes of pustulation occur for days to weeks, causing the patient severe discomfort and exhaustion. A telogen effluvium type of hair loss may develop in 2-3 months.

Upon remission of pustules, most systemic symptoms disappear. However, patients can experience an erythrodermic state or residual lesions of psoriasis vulgaris.

Circinate or annular-type pustular psoriasis predominates in childhood and runs a more subacute course with less severe manifestations. Often, recurrent episodes of annular or circinate erythematous plaques are seen, with pustules and scaling along the periphery. [1] These lesions appear primarily on the trunk and undergo peripheral expansion with central healing over hours to days. Other systemic signs and symptoms are either mild or absent.

The juvenile/infantile type of pustular psoriasis typically has a benign course. Systemic involvement is not common, and spontaneous remissions frequently occur.


Physical Examination in Pustular Psoriasis

Patients appear distressed, often tachypneic, tachycardic, and febrile. The oropharyngeal mucosa may be hyperemic, and a geographic tongue or fissured tongue may be appreciated. Skin findings include a generalized or patchy erythema studded with interfollicular pustules that may have an annular or generalized/nonspecific configuration. 

Lesions appear on the trunk, extremities, and, rarely, on the face. Flexural and anogenital accentuation may be present. Pustulation may also involve the nail beds, resulting in onychodystrophy, onycholysis, and defluvium unguium.

Peripheral scaling may be observed, especially in areas that have undergone pustulation. The rest of the physical examination depends on systemic complications.


Differentials in Pustular Psoriasis

The following conditions can mimic signs and symptoms of pustular psoriasis:


Laboratory Findings

Findings include the following:

  • Complete blood cell (CBC) count with absolute lymphopenia coinciding with polymorphonuclear leukocytosis up to 40,000/µL

  • Elevated erythrocyte sedimentation rate (ESR)

  • Serum chemistries - Increased plasma globulins; decreased albumin, calcium, and zinc; elevated BUN and creatinine if the patient is oligemic; elevated liver enzymes (aspartate transaminase [AST], alanine transaminase [ALT]) if liver damage has occurred

  • Urinalysis - Positive albumin; positive casts

  • Bacterial cultures and sensitivities of pustules - Negative in the absence of secondary infection, as are Tzanck preparations and viral cultures; loss of the cutaneous barrier may result in bacteremia


Histologic Changes

The overall architecture of the epidermis is similar to patients with psoriasis vulgaris, exhibiting parakeratosis, elongation of rete ridges, and thinning of the suprapapillary epidermis. The superficial dermis shows a mononuclear infiltrate and numerous neutrophils migrating from papillary capillaries to the epidermis. Neutrophils in the epidermis can aggregate between keratinocytes, where there is also spongiosis, forming pustules known as spongiform pustules of Kogoj, a characteristic histologic feature. [21]


Inpatient Treatment

Patients with generalized pustular psoriasis eruptions may require hospitalization to ensure adequate hydration, bed rest, and avoidance of excessive heat loss. Supportive therapy with bland topical compresses and saline or oatmeal baths helps sooth and debride affected areas.


Pharmacologic Therapy

There is no criterion standard therapy for pustular psoriasis. Disease severity and extent of skin involvement help guide treatment. 

First-line therapies

Current recommendations include initiation of systemic medications together with the proper supportive measures. Oral retinoids (acitretin, isotretinoin), methotrexate, cyclosporine, and infliximab are considered first-line therapies by the National Psoriasis Foundation Medical Board. [22] Hydroxyurea and 6-thioguanine have also been used with success. [23, 24]

In children, acitretin, cyclosporine, methotrexate, and etanercept are options for first-line therapy; however, no randomized controlled trials exist to confirm efficacy. [22]

Second-line therapies

Second-line therapies include biologic agents (etanercept and adalimumab) or topical treatments (corticosteroids, calcipotriene, tacrolimus) for more localized disease on the palms and soles. [22] An example of the palmoplantar condition is seen in the image below. [25] Guidelines regarding these second-line therapies are needed, as anecdotal reports describe paradoxical induction of pustular psoriasis with some biologics. [26, 27]

Combination therapy with use of a first- and second-line agent can also be considered. [22]

Palmoplantar pustular psoriasis, a type of pustula Palmoplantar pustular psoriasis, a type of pustular psoriasis that appears on the palms of the hands or the soles of the feet. Courtesy of Hon Pak, MD.

Newer therapies

The study of IL35RN gene mutations in the pathogenesis of generalized pustular psoriasis has led to new advances in treatment. Case reports have documented success with IL-1 receptor antagonists (eg, anakinra), and clinical trials are currently underway. [28, 29]

Case reports describe the efficacy of the drug tocilizumab in the treatment of biologic-induced plantar pustular psoriasis. [30] Tocilizumab is a monoclonal antibody that blocks IL-6 activity at both soluble and membrane-bound complexes, thus inhibiting IL-6‒dependant STAT1/STAT3 activation. However, reports describe rheumatoid arthritis patients treated with tocilizumab who develop paradoxical biologic-induced psoriasiform dermatitis. [31] Tofacitinib, a Janus kinase inhibitor, has also been tested as a potential therapy for psoriasis, but efficacy in pustular psoriasis is still undetermined. [32]


Several case reports discuss treatment of pustular psoriasis in pregnancy. Cyclosporine has been used with success in such cases, as well as infliximab (5 mg/kg). [33] The woman on infliximab delivered a healthy female baby via cesarean delivery. The neonate breastfed for 1 month and developed normally. No detectable adverse effects were noted, despite potential exposure to infliximab throughout gestation and breastfeeding. [34]



Oral psoralen plus UV-A

Patients usually have too much systemic toxicity and erythema during a flare to tolerate oral psoralen plus ultraviolet-A (PUVA). Treatment also requires frequent clinic visits (up to 4 d/wk), which is logistically difficult.

However, several studies have reported that PUVA is safe and effective in controlling flares of pustular psoriasis. Typically, PUVA is started once the patient has been stabilized on acitretin. PUVA has also successfully been used in combination with oral cyclosporine. [22]

UV-B and narrow-band UV-B

While little is written regarding the use of phototherapy for pustular psoriasis, [35] narrow-band UV-B may be a reasonable choice since it has achieved therapeutic effects similar to those of PUVA in other forms of psoriasis.

Retinoid plus PUVA

Acitretin is administered first at 0.2-0.5 mg/kg for 7 days, and then PUVA is added 3 times per week. As lesions resolve, acitretin can be withdrawn, and maintenance phototherapy with PUVA or narrowband UV-B can be continued as needed.


Patient Consultations

Request consultations with medical subspecialists according to the degree of systemic involvement.


Prognosis in Pustular Psoriasis

Older patients with von Zumbusch type have a poor prognosis. Death can result from sepsis, renal, hepatic, or cardiorespiratory failure during the acute erythrodermic stage.

Patients with a history of chronic psoriasis vulgaris prior to generalized pustular eruption tend to have a better prognosis than patients with more atypical forms of psoriasis.

In children, as long as serious secondary infections are avoided, episodes of pustular psoriasis have a good prognosis.

There is no cure for pustular psoriasis. Recurrent flares are common, even years after diagnosis. Patients often require continued therapy and avoidance of precipitating factors. [17]

Complications and morbidity in pustular psoriasis

Occasionally, acute respiratory distress syndrome may complicate generalized pustular psoriasis.

Other possible complications in pustular psoriasis include the following:

  • Secondary bacterial skin infections, hair loss (telogen effluvium), and nail loss

  • Hypoalbuminemia secondary to loss of plasma protein into tissues

  • Hypocalcemia

  • Renal tubular necrosis as a result of oligemia

  • Liver damage as a result of oligemia, neutrophilic cholangitis, [36] and general toxicity

  • Malabsorption and malnutrition

Death in pustular psoriasis may occur secondary to cardiorespiratory failure. This usually occurs in untreated patients.