Leg Ulcer

Clinical Vignette

A 55-year-old man presents with a non-healing, painful ulcer on his left shin. Please examine the lesion and discuss the potential diagnosis and management.

Positive Findings

  • A necrotic ulcer with ragged, bluish-purple overhanging edges located on the left shin.
  • Purulent surface with surrounding erythema and tenderness.
  • Rapid progression of the ulcer from a small pustule after minimal trauma (pathergy).
  • No associated systemic infection signs, but a history of fatigue and joint pain.

Relevant Negative Findings

  • No evidence of lymphadenopathy.
  • No signs of superadded infection (no fever, surrounding cellulitis, or foul smell).
  • No other ulcers or lesions present on the rest of the body.

What is the most likely diagnosis?

Pyoderma Gangrenosum, likely associated with underlying inflammatory bowel disease.

What is your differential diagnosis?

  1. Venous ulcer – Common cause of lower leg ulcers, typically painless with venous stasis signs.
  2. Arterial ulcer – Painful with pallor, thin shiny skin, or gangrene; peripheral vascular disease risk factors.
  3. Squamous cell carcinoma – Non-healing ulceration could indicate malignancy.
  4. Vasculitis (e.g., Wegener’s granulomatosis, Behçet's disease) – Associated with systemic symptoms.
  5. Infective ulcers – Bacterial, mycobacterial, or viral causes like ecthyma or herpetic ulcers.

How would you investigate this patient?

Blood tests:

  • FBC, ESR, CRP (inflammation markers)
  • ANA, ANCA (to rule out autoimmune causes)
  • Rheumatoid factor (for RA association)
  • Serum electrophoresis, immunoglobulins (to assess for haematological diseases)
  • Hba1c and lipid profile (to exclude diabetes and arterial causes)
  • LFTs (to check for hepatic causes like PBC)

Swabs for bacterial culture.

Ankle-brachial pressure index (ABPI) to assess arterial blood supply.

X-ray/MRI to exclude osteomyelitis.

Skin biopsy for histology (exclude malignancy and confirm diagnosis).

Colonoscopy if inflammatory bowel disease is suspected or not confirmed.

How would you manage this patient?

Immediate Measures:

  • Swab the wound for culture to exclude infection.
  • Biopsy the lesion to confirm pyoderma gangrenosum.
  • Topical steroids or tacrolimus ointment for localised small ulcers.
  • Pain relief and specialist wound dressing.

Referral:

  • Urgent referral to a dermatologist for confirmation of diagnosis and management.

Systemic Treatment:

  • High-dose oral prednisolone for larger ulcers.
  • Immunosuppressants: Ciclosporin, anti-TNFα inhibitors (e.g., infliximab), mycophenolate mofetil.
  • Avoid wide surgical debridement, which may worsen the ulcer.

Follow-up:

  • Regular wound care and dressing by a specialist nurse.
  • Long-term immunosuppression monitoring.

Viva Questions

What is Pyoderma Gangrenosum and its typical presentation?

  • A rare, chronic, and recurrent condition of skin ulceration, often associated with systemic diseases. Characterised by painful necrotic ulcers with bluish overhanging edges, often on the lower extremities.

What are the systemic conditions associated with Pyoderma Gangrenosum?

  • Inflammatory bowel disease (e.g., Crohn’s, ulcerative colitis), rheumatoid arthritis, myeloproliferative disorders (e.g., AML, CML), and primary biliary cholangitis (PBC).

What are the different forms of Pyoderma Gangrenosum?

  • Ulcerative (most common), Bullous, Pustular, Superficial granulomatous.

How is Pyoderma Gangrenosum diagnosed?

  • Clinically, as a diagnosis of exclusion. Biopsy shows neutrophilic infiltration, epidermal necrosis, but histology is non-specific.

How would you treat Pyoderma Gangrenosum?

  • Treat underlying conditions (e.g., IBD), use local therapies (topical steroids), systemic immunosuppressive therapies (e.g., prednisolone, ciclosporin), and wound care. Avoid surgical debridement in active stages.

What are some differential diagnoses for a non-healing leg ulcer?

  • Venous ulcers, arterial ulcers, squamous cell carcinoma, vasculitic ulcers, and infective ulcers (e.g., ecthyma).

What is the role of systemic corticosteroids in Pyoderma Gangrenosum?

  • Corticosteroids are the cornerstone of treatment for larger or more aggressive ulcers, helping to reduce inflammation and promote healing