The only definite indication for giving systemic coicosteroids in pustular psoriasis is:

Systemic coicosteroids are not recommended for psoriasis, because the disease tends to recur in more severe form after cessation of therapy. Systemic coicosteroids have dramatic sho term effectiveness. These can thus be used in extensive or severe form of generalized pustular psoriasis as a life saving measure when other drugs are contraindicated or ineffective. Ref: Anthony Du Vivier, Phillip H. McKee, Chapter 5, "Psoriasis", In the book, "Atlas of Clinical Dermatology", Elsivier Publication, 2002, 3rd Edition, Spain, Page 74