Material and Method: A retrospective medical chart review of Thai pustular psoriasis patients aged older than 15 years attended the Dermatology Clinic at Siriraj Hospital during July 2002 to October 2014 was conducted. Clinical feature, treatment modality, treatment response, and clinical course were reviewed.

Results: Fifty-three cases of pustular psoriasis were identified and studied. Female to male ratio was 1.9:1. Mean age was 42.2 years (SD = 15.8) and mean age at onset was 36.6 years (SD = 17.2). Twenty-three patients had concomitant plaquetype psoriasis vulgaris preceded pustular psoriasis. A mean time from onset of plaque-type psoriasis to development of pustular psoriasis was 7.9 years. The most common manifestations of pustular psoriasis were exanthematic type (60.4%), followed by localized type (22.6%) which included acrodermatitis continua of Hallopeau (13.2%) and pustulosis palmaris et plantaris (9.4%). Three common precipitating factors were inadequate sleep (30.2%), infection (30.2%), and medication (28.3%). Systemic corticosteroids withdrawal, accounting for 60% of medication-induced pustular psoriasis, was found to induce pustular psoriasis with an average onset of 1.7 weeks after withdrawal. Topical corticosteroids were the most common prescribed treatment (98.1%) while acitretin was the most frequently used systemic treatment (75.5%), followed by methotrexate (43.4%). Generalized type (exanthematic, acute generalized pustular psoriasis of Von Zumbusch and annular types) had rapid clearance of pustules ranged from 2-4 weeks, except for localized type which extended until 18 weeks. At one month, generalized type showed significant clearance at 70% compared to 25% in localized type (p<0.05). Recurrence was detected in 70% of all cases at a median time of 8 weeks. No mortality or severe complications from pustular psoriasis or treatment-related conditions was reported.

Conclusion: Pustular psoriasis is a rare condition in Thailand. Although some patients had severe forms of the disease, most patients had a benign clinical course that was controllable. However, relapse was common.

Keywords: pustular psoriasis, psoriasis, Thai, clinical characteristic