Pyoderma gangrenosum

Related Subjects: |Pyoderma gangrenosum |Pemphigus Vulgaris |Toxic Epidermal Necrolysis |Stevens-Johnson Syndrome |Necrotising fasciitis

💥 Always consider Pyoderma Gangrenosum (PG) when assessing ulcerated skin lesions. PG is a rare, non-infectious, inflammatory skin condition characterized by painful ulcers. It is often associated with systemic diseases like IBD, rheumatoid arthritis, and haematologic disorders.

ℹ️ About Pyoderma Gangrenosum

• ⚠️ Often mistaken for common ulcers - always think beyond “just venous ulcers.”
• 👩‍⚕️ Consider differential diagnoses including skin cancers and atypical infections.
• 🧪 If in doubt → refer to dermatology and consider biopsy.

🩺 Clinical Features

• 🔥 Pain: Severe pain, often disproportionate to appearance.
• 🟣 Edges: Undermined, violaceous/blue borders.
• ⚫ Base: Necrotic with purulent/granulomatous tissue.
• 📏 Size: May start small → rapidly expanding ulcers.
• 📍 Sites: Lower legs, surgical wounds, stomas (pathergy phenomenon).
• 🔄 Onset: Often begins as papules, pustules, or vesicles → ulcerates.
• 💥 Trigger: Minor trauma (pathergy) can precipitate.
• 🔗 Associated Diseases: RA, UC, Crohn’s, myeloma, haematologic malignancy.
• 💊 Drugs: Rarely hydroxyurea, GM-CSF.

🧬 Causes and Associations

• ❓ Idiopathic (~20%).
• 🧻 IBD: Crohn’s, ulcerative colitis.
• 🩸 Haematologic: Lymphoma, leukaemia, myeloma, myeloproliferative disease.
• 🛡️ Autoimmune: RA, primary biliary cirrhosis.
• 🦠 Other: Hepatitis, HIV, monoclonal gammopathies.

🔍 Investigations

• 📊 FBC, ESR, CRP (raised inflammatory markers).
• 🔬 Skin biopsy → neutrophilic dermatosis (helps exclude other causes but not pathognomonic).
• 🧫 Exclude infection (cultures, swabs).
• 📋 Screen for underlying systemic disease (IBD, RA, haematology).

🩹 Management

• 🚫 Avoid trauma: Surgery/skin grafting can worsen due to pathergy.
• 💊 Topical therapy: Potent corticosteroids, tacrolimus ointment.
• 💊 Pain relief: Analgesia is essential (often very painful ulcers).
• 🩼 Wound care: Non-adhesive dressings, prevent secondary infection.

💉 Systemic Treatments

• 🌟 Corticosteroids: First-line for moderate–severe disease.
• 💊 Immunosuppressants: Ciclosporin, methotrexate (steroid-sparing).
• 🧬 Biologics: TNF-α inhibitors (infliximab, adalimumab) - effective esp. in IBD-related PG.
• 🦠 Antibiotics: Only if secondary infection present (not primary therapy).

🚨 Key Teaching Point: PG is a neutrophilic dermatosis, not an infection. Surgical debridement often makes it worse (pathergy). Always treat underlying systemic disease.

🩺 Case 1 - Associated with Inflammatory Bowel Disease

A 32-year-old woman with ulcerative colitis develops a rapidly enlarging, extremely painful ulcer on her left shin. The lesion has a violaceous undermined edge and a purulent base. She has no signs of cellulitis. Management: 💊 High-dose corticosteroids or ciclosporin; optimise underlying IBD therapy. Wound care and pain relief are essential. Avoid: ❌ Surgical debridement (pathergy phenomenon can worsen lesions); avoid unnecessary antibiotics unless secondary infection is proven.

🩺 Case 2 - Pyoderma Gangrenosum with Rheumatoid Arthritis

A 60-year-old man with long-standing rheumatoid arthritis presents with an ulcer on his right calf, which started as a pustule and progressed to a painful necrotic ulcer with bluish borders. Blood cultures are negative. Management: 🩺 Systemic immunosuppression (steroids, ciclosporin, biologics such as TNF-α inhibitors in refractory cases). Multidisciplinary approach with dermatology and rheumatology input. Avoid: ❌ Mistaking for infective cellulitis and performing repeated surgical interventions; avoid stopping essential RA medications without rheumatology advice.