| Plaque-type psoriasis | Red, thick, scaly lesions with silvery scale | Stress, infection, trauma, medications, xerosis | Atopic dermatitis, irritant dermatitis, cutaneous T-cell lymphoma, pityriasis rubra pilaris, seborrheic dermatitis | Localized: topical therapy with corticosteroids, calcipotriene (Dovonex), coal tars, anthralin (Anthra-Derm) or tazarotene (Tazorac). |
| Generalized: phototherapy, systemic agents, combination therapy |
| Guttate psoriasis | Teardrop-shaped, pink to salmon, scaly plaques; usually on the trunk, with sparing of palms and soles | Streptococcal throat infection | Pityriasis rosea, secondary syphilis, drug eruption | Ultraviolet B phototherapy, natural sunlight |
| Pustular psoriasis, localized | Erythematous papules or plaques studded with pustules; usually on palms or soles (known as palmoplantar pustular psoriasis) | Stress, infection, medications | Pustular drug eruption, dyshidrotic eczema, subcorneal pustular dermatosis | Same as for plaque-type psoriasis |
| Pustular psoriasis, generalized | Same as localized with a more general involvement; may be associated with systemic symptoms such as fever, malaise and diarrhea; patient may or may not have had preexisting psoriasis | Stress, infection, medications | Pustular drug eruption, subcorneal pustular dermatosis | Systemic therapy and/or hospitalization usually required |
| Erythrodermic psoriasis | Severe, intense, generalized erythema and scaling covering entire body; often associated with systemic symptoms; may or may not have had preexisting psoriasis | Stress, infection, medications | Drug eruption, eczematous dermatitis, mycosis fungoides, pityriasis rubra pilaris | Systemic therapy and/or hospitalization usually required |