We have presented the results of treatment of 57 patients with psoriasis with topically applied mechlorethamine. Attempts to induce immunological tolerance to this chemical in 12 patients were unsuccessful. Although this is a useful treatment for psoriasis the high incidence of sensitization precludes its use until some method can be devised to prevent this complication.
Taylor JR, Halprin KM. Topical Use of Mechlorethamine in the Treatment of Psoriasis. Arch Dermatol. 1972;106(3):362-364. doi:10.1001/archderm.1972.01620120050010