Su et al reported criteria for the diagnosis of pyoderma gangrenosum. The authors are from the Mayo Clinic in Rochester and Mater Hospital in Dublin, Ireland.

Major criteria:

(1) rapid progression of a very painful, necrolytic cutaneous ulcer with irregular, violaceous and undermined, rolled border

(2) exclusion of other causes of cutaneous ulceration


Minor criteria:

(1) (history suggesting pathergy) OR (cribriform scarring)

(2) systemic disease present that is associated with pyoderma gangrenosum (inflammatory bowel disease, inflammatory arthritis, IgA gammopathy, malignancy, other)

(3) histopathologic findings (sterile dermal neutrophilia, mixed inflammation, lymphocytic vasculitis)

(4) rapid response to systemic steroid therapy



• Rapid progression is indicated (a) by characteristic margin expansion of 1-2 cm per day, OR (b) 50% increase in ulcer size within 1 month.

• Pain is typically out of proportion for the size of the ulceration.

• The lesion is typically preceded by a papule, pustule or bulla.

• Pathergy refers to ulcer development at the site of minor cutaneous trauma such as a pinprick.


Criteria for diagnosis - both of the following:

(1) both major criteria

(2) >= 2 minor criteria

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