Peristomal Pyoderma Gangrenosum at an Ileostomy Site

There are 4 types of PPG based on the clinical and histopathologic characteristics: ulcerative, pustular, bullous, and vegetative. Peristomal pyoderma gangrenosum tends to be either ulcerative or vegetative, with ulcerative being by far the predominant type. The onset of PPG is quite variable, occurring a few weeks to several years after stoma formation.⁵ Ulcer size can range from less than 3 cm to 30 cm.⁴ Lesions begin as deep painful nodules or as superficial hemorrhagic pustules, either idiopathic or following ostensibly minimal trauma. Subsequently, they become necrotic and form an ulceration. The ulcers can be single or multiple lesions, typically with erythematous raised borders and purulent discharge. The ulcers are extremely painful and rapidly progressive. After the ulcers heal, they often leave a characteristic weblike atrophic scar that can break down further following any form of irritation or trauma.⁵

A prompt diagnosis of PPG is important. A diagnosis of PPG should be considered when dealing with a noninfectious ulcer surrounding a stoma in patients with IBD or other autoimmune conditions.⁶ Because PPG is a rare skin disorder, it is likely to be missed and lead to unnecessary diagnostic workup and a delay in proper therapy. In our patient, a diagnosis of PPG was overlooked for other infectious and autoimmune causes. The diagnostic evaluation of a patient with PPG is based on 3 principles: (1) ruling out other causes of a peristomal ulcer, such as an abscess, contact dermatitis, or wound infection; (2) determining whether there is an underlying intestinal bowel disease in the stoma; and (3) identifying associated systemic disorders such as vasculitis, erythema nodosum, or similar processes.⁴ The differential diagnosis depends on the type and stage of PPG and can include malignancy, vasculitis, extraintestinal IBD, infectious disease, and insect bites. A review of the history of the ulcer is helpful in ruling out other diseases, and a colonoscopy or ileoscopy can identify if patients have an underlying active IBD. Swabs for smear and both bacterial and fungal cultures should be taken from the exudate and directly from the ulcer base. Biopsy of the ulcer also helps to exclude alternative diagnoses.⁶

The primary goals of treating PPG include to reduce pain and the risk for secondary infection, increase pouch adherence, and decrease purulent exudate.⁷ Although there is not one well-defined optimal therapeutic intervention, there are a variety of effective approaches that may be considered and used. In mild cases, management methods such as dressings, topical agents, or intralesional steroids may be capable of controlling the disease. Daily wound care is important. Moisture-retentive dressings can control pain, induce collagen formation, promote angiogenesis, and prevent contamination. Cleaning the wound with sterile saline and applying an anti-infective agent also may be effective. Application of ultrapotent topical steroids and tacrolimus ointment 0.3% can be used in patients without concomitant secondary infection. In patients who are in remission, human platelet-derived growth factor may be used. Intralesional injections of dilute triamcinolone acetonide or cyclosporine solution also can be helpful. Cyclosporin A was used as a systemic monotherapy to treat a 48-year-old man and 50-year-old woman with the idiopathic form of PPG. After 3 months of treatment, PPG had completely resolved and there were no major side effects.⁸ Other potential topical therapies that control inflammation and promote wound healing include benzoyl peroxide, chlormethine (topical alkylating agent and nitrogen mustard that has anti-inflammatory properties), nicotine, and 5-aminosalicylic acid. If an ulcer becomes infected, empiric antibiotic therapy should be given immediately and adjusted based on culture and sensitivity results.⁴

Systemic therapy should be considered in patients who do not respond to topical or local interventions, have a rapid and severe course, or have an active underlying bowel disease. Oral prednisone (1 mg/kg/d) has proved to be one of the most successful drugs used to treat PPG. Treatment should be continued until complete lesion healing, and low-dose maintenance therapy should be administered in recurrent cases. Intravenous corticosteroid therapy—hydrocortisone 100 mg 4 times daily or pulse therapy with intravenous methylprednisolone 1 g/d)—can be used for up to 5 days and may be effective. Oral minocycline 100 mg twice daily may be helpful as an adjunctive therapy to corticosteroids. When corticosteroids fail, oral cyclosporine 3 to 5 mg/kg/d often is prescribed. Studies have shown that patients demonstrate clinical improvement within 3 weeks of cyclosporine initiation, and it has been shown further to be more effective than either azathioprine or methotrexate.^4,8

Infliximab, a chimeric antibody that binds both circulating and tissue-bound TNF-α, has been shown to effectively treat PPG. A clinical trial conducted by Brooklyn et al⁹ found that 46% of patients (6/13) treated with infliximab responded compared with only 6% in a placebo control group (1/17). Although infliximab may result in sepsis, the benefits far outweigh the risks, especially for patients with steroid-refractory PPG.⁴ Adalimumab is a human monoclonal IgG1 antibody to TNF-α that neutralizes its function by blocking the interaction between the molecule and its receptor. Many clinical studies have shown that adalimumab induces and maintains a clinical response in patients with active Crohn disease. The biologic proved to be effective in our patient, but it is associated with potential side effects that should be monitored including injection-site reactions, pruritus, leukopenia, urticaria, and rare instances of alopecia.¹⁰ Etanercept is another potentially effective biologic agent.⁷ Plasma exchange, immunoglobulin infusion, and interferon-alfa therapy also can be used in refractory PPG cases, though data on these treatments are very limited.⁴

Unlike routine pyoderma gangrenosum—for which surgical intervention is contraindicated—surgical intervention may be appropriate for the peristomal variant. Surgical treatment options include stoma revision and/or relocation; however, both of these procedures are accompanied by failure rates ranging from 40% to 100%.⁵ Removal of a diseased intestinal segment, especially one with active IBD, may result in healing of the skin lesion. In our patient, removal of the residual and diseased J-pouch was part of the management plan. However,it generally is recommended that any surgical intervention be accompanied by medical therapy including oral metronidazole 500 mg/d and concomitant administration of an immunosuppressant.^1,3

Because PPG tends to recur, long-term maintenance therapy should always be considered. Pain reduction, anemia correction, proper nutrition, and management of associated and underlying diseases should be performed. Meticulous care of the stoma and prevention of leaks also should be emphasized. Overall, if PPG is detected and diagnosed early as well as treated appropriately and aggressively, the patient likely will have a good prognosis.⁴