A patient with plaque psoriasis is described as having a generalized pustular reaction evoked by the topical use of crude coal tar. This pustular response was reproduced in a circumscribed area by an open patch test. It is suggested that hypersensitivity in the psoriatic, when the skin is one of the target organs, may result in generalized pustulation producing clinical features identical with those originally detailed by von Zumbusch.
Ogawa M, Baughman RD, Clendenning WE. Generalized Pustular PsoriasisInduction by Topical Use of Coal Tar. Arch Dermatol. 1969;99(6):671-673. doi:10.1001/archderm.1969.01610240029004