Pyoderma Gangrenosum Around a Stoma

Pyoderma gangrenosum (PG) occurring around a stoma — known as peristomal pyoderma gangrenosum (PPG) — is a rare but serious neutrophilic dermatosis characterised by rapidly enlarging, painful ulcers on the skin immediately surrounding the stoma. It is not caused by infection. PPG is the most common site for PG in people with an ostomy and demands prompt specialist assessment, as misdiagnosis and inappropriate treatment can cause significant harm.

What Is Pyoderma Gangrenosum?

Pyoderma gangrenosum is a chronic, inflammatory skin disorder belonging to the group of conditions known as neutrophilic dermatoses — diseases in which an abnormal accumulation of neutrophils in the skin drives tissue destruction. Despite the name, it involves neither pyogenic bacteria nor gangrene in the classical sense; the terminology reflects the appearance of early lesions rather than their cause.

PG affects approximately 3–10 people per 100,000 per year in the general population. When it occurs in people with a stoma, it typically develops around the peristomal skin — the area covered by the baseplate or wafer — making appliance management extremely difficult.

Who Is at Risk?

PPG is strongly associated with underlying systemic conditions:

• Inflammatory bowel disease (IBD): Crohn’s disease and ulcerative colitis account for the majority of cases. PPG can occur even after colectomy or proctocolectomy, when the bowel disease is considered surgically treated.
• Rheumatoid arthritis and other autoimmune conditions
• Haematological malignancies, including myeloma and leukaemia
• Solid organ malignancies (less commonly)

In a significant minority of cases no underlying condition is identified (idiopathic PG).

The Role of Pathergy

A hallmark feature of PG is pathergy — the tendency for minor skin trauma to precipitate or worsen ulcers. For people with a stoma, this has critical implications: repeated adhesive removal, ill-fitting appliances, minor abrasions, or surgical revision of the stoma can all trigger new ulceration. Pathergy also means that surgical debridement of PPG wounds is contraindicated and can cause rapid deterioration.

Recognising Peristomal Pyoderma Gangrenosum

Early Signs

PPG typically begins as one or more small pustules or erythematous nodules on the peristomal skin. These may initially be mistaken for folliculitis, a contact dermatitis reaction to the adhesive, or a fungal infection.

Established Ulceration

Within days, the lesion breaks down to form a painful ulcer with:

• A violaceous (purple-blue), undermined wound edge — this overhanging border is a classical diagnostic clue
• A necrotic or purulent wound bed, which may appear infected but cultures are usually negative or show only superficial colonisation
• Rapid centrifugal spread, sometimes encircling the stoma entirely
• Severe pain, often disproportionate to the wound size

Differential Diagnosis

Because no single diagnostic test confirms PG, clinicians must exclude other causes of peristomal ulceration. The differential includes:

• Peristomal infection (bacterial or fungal)
• Contact or irritant dermatitis
• Crohn’s disease cutaneous manifestations (metastatic Crohn’s)
• Ischaemic necrosis
• Malignancy at the stoma site
• Vasculitis

Diagnosis is clinical, supported by biopsy (which shows a dense neutrophilic infiltrate), wound culture (typically negative for significant pathogens), and investigation of underlying systemic disease.

Treatment and Management

Management of PPG requires a multidisciplinary approach involving dermatology, gastroenterology or the relevant specialty managing any underlying disease, and a specialist stoma care nurse.

Systemic Immunosuppression

This is the cornerstone of treatment:

• Systemic corticosteroids (prednisolone) are usually the first-line agent, producing a rapid anti-inflammatory effect.
• Ciclosporin is an effective alternative or steroid-sparing agent.
• Biologics, particularly TNF-alpha inhibitors such as infliximab, have an established evidence base — especially in IBD-related PPG — and are increasingly favoured in refractory or severe cases.
• Dapsone, mycophenolate mofetil, and azathioprine are used as steroid-sparing maintenance agents in selected patients.

Topical and Local Therapies

For mild or localised disease, potent topical corticosteroids (applied carefully away from the stoma opening) or topical tacrolimus may be tried. Intralesional corticosteroid injections are used occasionally but must be performed cautiously given the risk of pathergy.

Wound Care Principles

Conventional wound care principles must be adapted for PPG:

• Avoid debridement. Surgical or sharp debridement is contraindicated due to pathergy.
• Minimise trauma. Use gentle adhesive-removal techniques, consider barrier films before appliance application, and extend wear time where clinically safe.
• Moist wound healing. Non-adherent dressings under the appliance baseplate can support wound healing while absorbing exudate.
• Pain management. PPG is frequently very painful; adequate analgesia, including consideration of topical lidocaine for dressing changes, is an important element of care.

Appliance Adaptation

Maintaining a functional, leak-free seal over ulcerated, irregular peristomal skin is one of the most challenging practical aspects of PPG. Options include:

• Mouldable or soft-convex baseplates shaped to the wound contour
• Barrier rings or paste to fill wound edges
• Frequent reassessment of the appliance template as the wound changes shape

Your stoma care nurse is central to this ongoing adaptation and should be involved from the outset.

Prognosis and Follow-Up

With appropriate systemic treatment, most patients with PPG achieve wound healing, although this can take weeks to months. Recurrence is possible, particularly if underlying IBD remains active or if the precipitating condition is not controlled. Long-term dermatology follow-up is advisable. Patients should be counselled that this is a chronic, relapsing condition in some cases, and encouraged to report any new skin changes promptly.

The Bottom Line

Peristomal pyoderma gangrenosum is a serious, immune-mediated condition that mimics infection but requires immunosuppressive — not antimicrobial — treatment. Its key features are violaceous, undermined ulcer edges, severe pain, and worsening with trauma (pathergy). Early specialist diagnosis is essential to avoid the harm caused by mismanagement. Anyone with a stoma who develops painful, rapidly worsening skin breakdown around their stoma should seek urgent review from their stoma care nurse or medical team.