Check these resources.
Lester LU, Rapini RP. Dermatologic manifestations of colonic disorders. Curr Opin Gastroenterol. 2009 Jan;25(1):66-73.
Case report with discussion of literature:
Farhi D, et al. Misleading pustular plaques of the lower limbs during Crohn’s disease: two case reports. J Med Case Rep. 2007;1:109.
List of case reports of skin manifestations in Crohn’s Disease.