How are skin findings associated with Crohn’s disease managed?

Management of Skin Manifestations in Crohn's Disease

Surgical excision of Crohn's disease skin tags is not recommended due to high rates of postoperative complications including poor wound healing and subsequent proctectomy. 1

Classification of Skin Manifestations

Skin manifestations in Crohn's disease can be categorized into four main groups:

1. Specific lesions - Share the same granulomatous histopathology as intestinal Crohn's disease

   • Metastatic Crohn's disease
   • Perianal disease (tags, fissures, fistulas)

2. Reactive lesions - Different histopathology but pathophysiologically linked

   • Pyoderma gangrenosum
   • Erythema nodosum
   • Sweet's syndrome

3. Associated conditions

   • Psoriasis
   • Cutaneous vasculitis

4. Treatment-induced lesions

   • Anti-TNF-induced skin inflammation
   • Drug reactions

Management Approach by Lesion Type

Perianal Disease

• Skin tags: Avoid surgical excision due to high complication rates 1
• Anal fissures: Usually painless and heal spontaneously in >80% of cases; lateral sphincterotomy only for refractory cases 1
• Perianal fistulas:
  • Low fistulas: Fistulotomy for patients without rectal inflammation
  • High fistulas: Noncutting setons for patients with active rectal inflammation 1
  • Pelvic MRI is the most accurate test for assessment before surgical intervention 1

Erythema Nodosum (EN)

• Presents as tender, red/violet subcutaneous nodules (1-5cm), typically on extensor surfaces, particularly anterior tibial areas
• More common during active disease
• Treatment:
  • Primary approach: Treat underlying Crohn's disease activity
  • Systemic corticosteroids usually required
  • For resistant/frequent relapses: Azathioprine, infliximab, or adalimumab 1

Pyoderma Gangrenosum (PG)

• Deep excavating ulcerations with sterile purulent material
• Often preceded by trauma at the site (pathergy)
• Common locations: Shins and adjacent to stomas
• Treatment:
  • Infliximab has demonstrated efficacy in controlled trials
  • Alternative options: Systemic corticosteroids, cyclosporine, tacrolimus 1

Sweet's Syndrome

• Tender, red inflammatory nodules/papules on upper limbs, face, or neck
• Strong predilection for women and patients with colonic involvement
• Treatment: Systemic corticosteroids 1

Metastatic Crohn's Disease (MCD)

• Rarest cutaneous manifestation
• Defined as skin lesions in areas noncontiguous with the GI tract
• Variable morphology, can arise anywhere on the skin
• Treatment:
  • Biologics (anti-TNF agents) have shown promise, even in refractory cases
  • Other options with mixed results: Topical/intralesional/systemic corticosteroids, antibiotics, immunosuppressants 2

Anti-TNF-Induced Skin Inflammation

• Paradoxical inflammation that is a class-drug effect
• Usually reversible upon drug cessation
• Management:
  • Refer to dermatologist when diagnosis is uncertain
  • For psoriasiform/eczematous lesions: Topical management for mild cases
  • For moderate/severe psoriasiform pathology: Switch to another TNFα inhibitor or change biologic class
  • For lupus-like lesions: Discontinue the TNFα inhibitor 1

Special Considerations

1. Infection screening:

   • All patients with flares should have stool cultures for entero-invasive bacterial infections and C. difficile assay 1
   • Purified protein derivative skin testing before treatment with infliximab to assess for latent tuberculosis 1

2. Multidisciplinary approach:

   • Dermatology consultation for complex or treatment-resistant skin manifestations
   • Assessment of de novo cutaneous lesions arising during TNFα inhibitor treatment should be multidisciplinary 1

3. Monitoring:

   • Regular skin examinations for patients on immunosuppressive therapy
   • Particular vigilance for those on thiopurines due to increased risk of nonmelanoma skin cancer 3

Treatment Selection Algorithm

1. For perianal disease: Control intestinal disease activity first, consider infliximab for fistulizing disease
2. For reactive lesions (EN, PG, Sweet's):
   • Mild: Treat underlying Crohn's disease
   • Moderate-severe: Add systemic corticosteroids
   • Refractory: Consider biologics (infliximab, adalimumab)
3. For metastatic Crohn's disease: Biologics as first-line therapy
4. For treatment-induced lesions:
   • Mild: Topical therapy
   • Moderate-severe: Consider switching biologic class

Remember that controlling the underlying intestinal inflammation is often key to managing many cutaneous manifestations of Crohn's disease.