Man vs flowerpot: a worsening injury
Last reviewed: February 2025
Author: Dr Stanley Leong, Dermatology and Paediatric Registrar, NZ.
Reviewing dermatologist: Dr Ian Coulson (2025).
Edited by the DermNet content department
Background
A 50-year-old gentleman knocked his lower legs against a flowerpot and sustained a superficial abrasion.
Within a week, the lesion became violaceous (purple-red colour) and extremely tender to touch. Over time, he had similar multiple lesions appearing on both lower legs.
The lesions slowly increased in size and started to ulcerate. His locomotion is severely limited due to the pain.
This gentleman does not have a history of autoimmune disorders, malignancy, or inflammatory bowel disease.
What is the likely diagnosis?
This is pyoderma gangrenosum. It is a type of autoinflammatory disorder, known as neutrophilic dermatoses.
It is rare. It usually presents as a rapidly enlarging, extremely tender lesion that subsequently ulcerates.
It is a diagnosis of exclusion. It is important to rule out atypical bacterial or deep fungal infection as they may present similarly.
It is characterised by a full-thickness ulcer with blue/purple undermined borders and by pathergy.
What are the differential diagnoses?
What treatments are available?
Meticulous wound care is crucial. Treatment of pyoderma gangrenosum is mainly non-surgical. Surgical debridement should be avoided due to risk of pathergy.
Treatment modality largely depends on the size of the ulcer.
Small ulcers are often treated with potent topical corticosteroids while large ulcers often require systemic treatment.
Systemic treatment for pyoderma gangrenosum includes:
- Systemic corticosteroids: eg, oral prednisone or intravenous methylprednisolone
- Oral ciclosporin
- Oral methotrexate, mycophenolate, azathioprine
- Oral dapsone
- Biologic agents: infliximab, secukinumab, adalimumab, etanercept, ustekinumab, anakinra, upadacitinib.
