Pyoderma Gangrenosum

Exam Cram

• Pyoderma Granulosa is an autoimmune condition associated with other autoimmune conditions, e.g. IBD

• Presentation: begins with a papule that breaks down into an ulcer

• Diagnosis: biopsy

• Management: topical tacrolimus or steroids, moist wound dressings

Outline

Background 

• Pyoderma gangrenosum isn't an infection and doesn't cause gangrene

• Instead it is an autoimmune condition

Assessment

History:

• Papule, vesicle or pustule ulcerating within 4 days

• Can be peri-stomal

• Multiple ulcers, particularly anterior leg

Examination:

• Peripheral erythema undermining border with tenderness at ulcer site

• Necrotic base with blue edges

• Cribiform / wrinkled paper scare at site of healed ulcer

Investigations

• Pathergy test: positive

• Biopsy: almost diagnostic

Diagnosis

Diagnostic criteria: Maverakis 2018- c.90% sensitivity & specificity: positive biopsy + four criteria

• Biopsy: ulcer edge show neutrophilic infiltrate

• Minor criteria (4/8)

  1. Infection excluded

  2. Pathergy +ve

  3. PMH- IBD or inflammatory arthritis

  4. HPC- papule, vesicle or pustule ulcerating within 4 days

  5. Peripheral erythema undermining border with tenderness at ulcer site

  6. Multiple ulcers, at least on anterior lower leg

  7. Cribiform / wrinkled paper scare at site of healed ulcer

  8. Decreasing size in response to immunosuppression

Differentials: 

• Pyogenic Granuloma - is a papule/ lump, easy to confuse names

Classification (aetiology)

1. Primary (idiopathic)

2. Secondary association

   1. IBD- Crohn's Disease & UC 

   2. Rheumatoid Arthritis 

   3. Leukaemias

   4. Viral Hepatitis AE 

   5. GPA 

   6. Behcet's Disease 

   7. Cocaine

Management

1. Topical tacrolimus

2. Topical steroids

3. Azathioprine, cyclophosphamide, MMF, Infliximab IV

References

1. https://dermnetnz.org/topics/pyoderma-gangrenosum

2. https://www.nhs.uk/conditions/pyoderma-gangrenosum/

3. Schmieder SJ, Krishnamurthy K. Pyoderma Gangrenosum. [Updated 2023 Jul 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482223/

Page written in 2024.