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Pyoderma Gangrenosum

Key Points

  • Pyoderma gangrenosum is a type of ulcerating neutrophilic dermatosis.
  • The classic morphology of pyoderma gangrenosum is an ulcer with a violaceous rim and undermined border.
  • PG lesions may develop very rapidly (in days) and may be triggered or exacerbated by minimal trauma.
  • PG is a diagnosis of exclusion; inflammatory and infectious conditions may mimic PG-like ulcers. PG may occur in association with an underlying systemic disorder.
  • Treatment of PG requires both management of inflammation and optimized wound care. Advanced lesions may often require systemic immunosuppression.

Introduction

Pyoderma gangrenosum (PG) is a neutrophilic dermatosis defined by its characteristic morphology. Ulcerating lesions marked by a violaceous rim and undermined border may develop rapidly (in days) and may be triggered or exacerbated even by minimal trauma (pathergy). It is a diagnosis of exclusion and can be simulated by various inflammatory, vascular and infectious conditions. PG lesions may occur in isolation or occur in association with an underlying systemic disorder, such as a rheumatologic disease, inflammatory bowel disease, malignancy (especially hematologic malignancy), immunodeficiency, or infection. Lesions may also be induced by medications; for example, exogenous granulocyte-monocyte colony stimulating factor (GM-CSF) may cause PG-like lesions. In these cases, lesions may respond by stopping the inciting medication and topical treatment. The diagnostic evaluation of PG thus requires formal exclusion of conditions that may mimic this disorder in addition to diagnostic work-up for associated systemic diseases.

Treatment is determined by the extent and rapidity of the cutaneous process and requires both aggressive management of inflammation and optimal wound care. Though treatment of early lesions can often be managed through topical medications and good wound care, advanced or rapidly expanding lesions may require systemic immunosuppression to halt progression and promote healing. PG lesions may be exquisitely painful, sometimes out of proportion to their clinical appearance or size; reduction in pain associated with a lesion represents an important early sign of effective treatment. Lesions often heal with a very characteristic cribiform, atrophic scar pattern.