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Practice Easily Missed?

Pyoderma gangrenosum

BMJ 2023; 382 doi: (Published 06 September 2023) Cite this as: BMJ 2023;382:e075863
  1. Katie C Y Yeung, medical student1,
  2. Emily M O’Connor, family physician, associate professor2,
  3. Peter R Hull, dermatologist, professor of medicine3
  1. 1School of Medicine, Queen’s University, Kingston, Ontario, Canada
  2. 2Department of Family Medicine, Queen's University, Kingston, Ontario, Canada
  3. 3Division of Clinical Dermatology and Cutaneous Science, Dalhousie University, Halifax, Nova Scotia, Canada
  1. Correspondence to: P R Hull peter.hull{at}

What you need to know

  • Pyoderma gangrenosum presents as a rapidly evolving ulcerative lesion

  • A key diagnostic clue is severe pain that may seem out of proportion to the clinical appearance

  • Pyoderma gangrenosum is often associated with underlying systemic disease

  • Missing a diagnosis of pyoderma gangrenosum can result in inappropriate debridement of the skin and subcutaneous tissue, leading to serious harm

A 51 year old woman presented to her general practitioner with a very painful ulcer on her right leg. She had no notable medical history and did not take any medications. She did not recall sustaining any recent injury to her leg but reported having noticed several small pustules in the same area the previous week. On examination, her temperature was 37.9°C, and there was a single purulent 2×2 cm ulceration on her leg with dusky purple borders and surrounding erythema. She was prescribed topical antibiotics. She returned two weeks later with worsening pain. Her ulcer now measured 9×7 cm with undermined borders and peripheral erythema. Her severe pain and the rapidly evolving ulceration were noted.

Bloodwork revealed mildly elevated C reactive protein level and erythrocyte sedimentation rate; all other parameters were within normal limits. A punch biopsy was taken, which showed neutrophilic infiltrate with no suspicion for malignancy or vasculitis. Deep swabs for fungal and bacterial culture showed no growth, and further workup to exclude possible differentials for a non-healing ulcer was unremarkable.

Her general practitioner noted worsening of the ulcer at the site of biopsy consistent with pyoderma gangrenosum. High dose oral prednisone was started, with an urgent referral to dermatology. A diagnosis of pyoderma gangrenosum was made, and the patient was advised to continue with systemic steroids while avoiding any further trauma (such as debridement) to the lesion. The ulcer rapidly improved and eventually resolved completely.

What is pyoderma gangrenosum?

Pyoderma gangrenosum is a rare autoinflammatory dermatosis …

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