Pyoderma gangrenosum sometimes takes a recalcitrant course that is unresponsive to standard immuno-suppression with corticosteroids and/or cyclosporin A. In these cases improvement of painful ulcerations is a therapeutic challenge. We report a 17-year-old boy with severe pyoderma gangrenosum treated successfully with mycophenolate mofetil and autologous keratinocyte transplantation using an esterified hyluronic acid delivery system.