Pustular Psoriasis (Generalized)

Key Points
Rare form of psoriasis which is typically widespread
Cause is unknown, though some cases may be related to chronic plaque psoriasis
Consists of reddened, dry skin which is tender, quickly followed by the formation of small pustules which coalesce into larger lesions

Pustular psoriasis is a rare form of psoriasis which is typically widespread. The condition initially consists of the sudden reddening of skin in the affected area, which is accompanied by dryness and tenderness. This is quickly followed by the formation of small, non-infected pustules. The initial eruption is accompanied by severe fever, chills, headache, increased pulse rate, loss of appetite, nausea and weakness. Within approximately one day, pustules coalesce into much larger lesions, which then dry and peel. New crops of lesions may erupt every few days or weeks in the affected area.

The cause of pustular psoriasis is unknown. While most cases are idiopathic, some cases may be associated with the presence of chronic plaque psoriasis, the most common form of the condition. Certain trigger factors, such as sudden withdrawal of corticosteroids, certain medications (lithium, salicylates, indomethacin, iodide), some strong topical medications (coal tar, dithranol), infection, and pregnancy, have been implicated in the development of the condition.

Differential Diagnosis (Other conditions with similar appearance)
Subcorneal pustular dermatosis
Acute generalized exanthematous pustulosis (drug eruption)
Gram-negative septicemia
Infected generalized atopic dermatitis and/or seborrheic dermatitis

Diagnosis
Key Points
Diagnosis based on characteristic appearance of the affected area
Skin biopsy, laboratory, blood and other tests may be performed to confirm diagnosis and check for associated conditions

Pustular psoriasis is typically diagnosed based on the characteristic appearance of the affected area. Skin biopsy, laboratory, blood and other tests may be performed to confirm the diagnosis and to check for associated conditions.

Treatment
Due to its sudden onset and severity of symptoms, hospitalization is typically required
Can present life-threatening complication during initial eruption
Relapses are very common

The initial presentation of pustular psoriasis can be life-threatening due to the severity of symptoms and increased risk of secondary infection, in addition to protein and electrolyte imbalances, so hospitalization is required. Treatment involves the use of topical compresses, in addition to antibiotics in cases accompanied by infection. In very severe cases, medications such as retinoids, corticosteroids, methotrexate, colchicines, cyclosporin, and hydroxyurea may be used if the affected person is in severe distress. Phototherapy has also been shown to be effective when used in combination with oral psoralens.