Pyoderma gangrenosum (PG) is an autoimmune disorder of unknown etiology that leads to painful skin necrosis. PG is commonly associated with other inflammatory diseases such as Crohn disease, inflammatory bowel disease, arthritis, Bechet’s, a monoclonal gammopathy, and hematologic malignancy, but also may be idiopathic.[1]^,2 Pathergy, the development of skin lesions in the area of trauma or the enlargement of initially small lesions, is commonly seen with PG, especially if debridement of necrotic tissue is attempted. Neutrophilic dermatosis occurs with altered neutrophilic chemotaxis or neutrophil hyperactivity, and is thought to be part of the pathology. 

PG ulcers usually begin as small pustules or blisters and become larger with a violaceous border, surrounding erythema, and undermining at the edges. The first lesion may be at the site of minor trauma, but will progress and enlarge rapidly. They are painful, necrotic, and usually recurring. Sometimes PG will appear in groups of lesions at different stages of formation or healing. They do not respond to standard care if diagnosed as another wound type, and indeed may worsen if the standard D/TIME care is administered.¹

As there is no diagnostic test to confirm PG and multiple other conditions that resemble PG, a correct diagnosis relies on clinical presentation and exclusion of other causes. The following table lists the systemic diseases most often associated with PG. Tests such as biopsy and lab work are useful to rule out other diagnoses, but do not confirm PG.

Five different variants of PG have been identified with the following characteristics:

• Classic PG – commonly seen on the lower extremities; produces cribriform scarring. Patient complains of fever, malaise, arthralgia, and myalgia.
• Parastomal PG – occurs close to abdominal stomas, usually in patients with irritable bowel disease, ileostomies, or colostomies that have been placed for malignancies; may present with bridges of epithelium that traverse the ulcer base; do not respond well to standard care
• Pustular PG – commonly seen on the trunk and extremity extensor surfaces of patients with irritable bowel disease; generally stalls at the pustular stage and may persist for months
• Bullous PG – commonly seen on the upper limbs and face; is associated with hematologic conditions with poor prognosis; presents as concentric painful bullous lesions that spread rapidly
• Vegetative PG – is less aggressive, more superficial, with undermining; may respond well to local treatment[2]

Systemic management includes treatment of any underlying disease; systemic corticosteroids (>60 mg/day) and cyclosporine are recommended for severe or widespread disease, and indeed are best supported in the literature.⁴ Other therapies that have been used in patients with PG include antibiotics (dapsone and minocycline), clofazimine, azathioprine, methotrexate, chlorambucil, cyclophosphamide, thalidomide, tacrolimus, mycophenolate, mofetil, IV immunoglobulin, plasmapheresis, and infliximab.[3] Autologous skin grafting is a relative contraindication because, when already present, PG can develop in other unrelated areas of the skin.[4]

Goals of wound care are to minimize pain, prevent infection, and promote re-epithelialization. Topical steroids, topical tacrolimus, nicotine patches, and intralesional steroids have been used for mild or moderate disease. Debridement of adhered tissue is contraindicated and may cause pathergy; however, as the necrotic tissue loosens with re-epithelialization, it may be gently removed with sterile forceps. Keeping the lesions covered with a non-adherent mesh or silicone-backed wicking foam that will allow drainage to escape to a secondary dressing can help alleviate the pain associated with PG wound care. Cellular/tissue biological dressings can also facilitate re-epithelialization without the effects of pathergy that may occur with skin grafts.⁴

In summary, PG is an autoimmune disorder that results in painful skin lesions that are usually as severe as the underlying concomitant disease. Treatment is predicated on treatment of the underlying disorder and conservation wound management.

[1] Hamm R, Shah JB. Atypical Wounds. In Hamm R (Ed). Text and Atlas of Wound Diagnosis and Treatment, 2^nd Edition. New York, NY: McGraw Hill Education. 2019;235-268.

[2] Wines N, Wines M, Ryman W. Understanding pyoderma gangrenosum: A review. Med Gen Med. 2001;3(3):6. Available at https://www.medscape.com/viewarticle/408145. Accessed August 2, 2018.

[3] Wollina U. Clinical management of pyoderma gangrenosum. Am J Clin Dermatol. 2002;3(3):149–158.

[4] Panuncialman J, Falanga V. Unusual causes of cutaneous ulceration. Surg Clin North Am. 2010;90(6):1161-1180.