Four patients with pyoderma gangrenosum were found to have an abnormality of delayed hypersensitivity that was characterized by cutaneous anergy and dissociation between macrophage inhibitory factor production and blastogenic response in vitro. Three of these four patients had a rheumatoid-like polyarthritis. One patient responded to conservative therapy but three required high doses of corticosteroids for healing of the ulcers.
Lazarus GS, Goldsmith LA, Rocklin RE, Pinals RS, de Buisseret J, David JR, Draper CW. Pyoderma Gangrenosum, Altered Delayed Hypersensitivity, and Polyarthritis. Arch Dermatol. 1972;105(1):46-51. doi:10.1001/archderm.1972.01620040018003