Most cases of<unk>  present in patients with existing or prior psoriasis conditions. However, there are many cases of<unk>  that arise without a history of psoriasis. The Department of Dermatology of the University of São Paulo proposed a classification for these two conditions. Pso+ represents patients with a personal history of psoriasis and pso- represents patients with no history of psoriasis. They also identified a common factor among patients in each group: In the pso+ group, the most common precipitating factor is corticosteroid withdrawal. In the pso- group, the most common precipitating factor is infection. In a large portion of cases, the disease is brought on by some triggering factor. Through research and observation, many of these factors have been identified. The following table, from an article in Cutis, lists a few factors that have been observed as influential in the onset of<unk> . Provocative Factors Influencing Pustular Psoriasis Drugs: lithium, aspirin, salicylates, methotrexate, corticosteroids, progesterone, phenylbutazone, trazodone, penicillin, hydroxychloroquine Irritation from topical therapy: coal tar, anthralin Infections: dental, upper respiratory Pregnancy Solar irradiation Source: "Table II", "Pustular Psoriasis" Farber and Nall, 1993
Generalized pustular psoriasis
Inverse psoriasis
Guttate psoriasis
Localized pustular psoriasis
Annular pustular psoriasis
Retiform parapsoriasis
Exanthematic pustular psoriasis
Parapsoriasis