Clinical features

Histopathological features

Ulcerative PG

1.     Rapid progression of a painful, necrolytic cutaneous ulcer with an irregular, violaceous, and undermined border

2.     History suggestive of pathergy or clinical finding of cribriform scarring

3.     Systemic diseases associated with PG

4.     Treatment response (rapid response to systemic steroids)

Sterile dermal neutrophilia, ± mixed inflammation, ± lymphocytic vasculitis

Pustular PG

1.     Painful pustules (0.5–2 cm diameter), with surrounding halo

2.     Associated inflammatory bowel disease

3.     Improvement with control of inflammatory bowel disease

4.     Systemic steroids are the mainstay of treatment [20]

Neutrophilic infiltrate; subcorneal/subepidermal neutrophils

Vegetative PG

1.     Chronic erythematous plaques, with sinus formation; shallow ulceration or erosions and discomfort

2.     No associated disease

3.     Response to minor treatment measures (topical and intralesional steroids and less commonly, oral coricosteroids and other immunosuppressive agents) [21]

Dermal and histiocytic

dermal infiltrate, granuloma formation

Bullous PG

1.     Painful, inflammatory bullae; rapidly enlarging painful vesicles and bullae; coalescing of grouped bullae

2.     Associated hematologic malignancy in as many as 70%

3.     Pathergy

4.     Rapid response to steroids

Neutrophilic dermal infiltrate, subepidermal bullae ± epidermal

necrosis