The only definitive indication of systemic steroids in psoriasis-
Only indication for use of systemic steroids is generalized pustular psoriasis in pregnancy ( impetigo herpetiformis). IADVL textbook of dermatology page 1049
Pustular psoriasis
Impetigo herpetiformis
Psoriatic ahropathy
Erythroderma
Papulosquamous disorders