
Pyoderma gangrenosum is an uncommon, ulcerative cutaneous condition of uncertain etiology. It is associated with systemic diseases in at least 50% of patients who are affected. [1, 2] The diagnosis is made by excluding other causes of similar-appearing cutaneous ulcerations, including infection, malignancy, vasculitis, collagen vascular diseases, diabetes, and trauma. In a process termed pathergy, new ulcerations may occur after trauma or injury to the skin in 30% of patients who already have pyoderma gangrenosum. (See Presentation, DDx, and Workup.)Patients with pyoderma gangrenosum may have involvement of other organ systems that manifests as sterile neutrophilic infiltrates. Culture-negative pulmonary infiltrates are the most common extracutaneous manifestation. [3] Other organs systems that may be involved include the heart, the central nervous system, the gastrointestinal (GI) tract, the eyes, [4, 5] the liver, the spleen, the bones, and the lymph nodes. (See Presentation and Workup.)n Therapy for pyoderma gangrenosum involves the use of anti-inflammatory agents, including antibiotics, corticosteroids, immunosuppressive agents, and biologic agents. The prognosis is generally good; however, the disease can recur and residual scarring is common. (See Prognosis, Treatment, and Medication.)