INTRODUCTION
P yoderma gangrenosum (PG) is a rare, chronic condition of complex etiology first described in 1930 by Brusting, Goeckerman, and O’Leary.1 The term PG describes a painful disfiguring ulcerative process, which more commonly affects women between 20 and 50 years old, but can affect either sex and can occur at any age including childhood (4% of cases).2 Roughly 50 percent of cases are idiopathic, while the other half of cases is associated with underlying systemic illness, of three main categories: inflammatory bowel disease (IBD), systemic arthritis including rheumatoid arthritis (RA), and bone marrow dyscrasias (paraproteinemia, acute myelogenous leukemia, myelodysplasia).2 Given the association of PG with autoimmune illnesses, an immune dysregulation pathogenesis is implicated, though the exact pathogenesis remains to be elucidated.PG belongs to the family of neutrophilic dermatoses. It represents an inflammatory process that initially manifests as an enlarging papule or pustule on a violaceous base that rapidly involutes into superficial to deep necrotic ulcers with overlying exudates. PG is classically well-circumscribed by an undermined border outlined by a gray to violaceous rim. Erythematous rims may indicate active areas of inflammation. Sites of involvement most commonly include the pretibial region of the lower extremities and sites of cutaneous injury. Pathergy, a phenomenon in which trivial cutaneous injury or trauma instigates new PG lesions and exacerbates existing ulcers, is seen in 20 to 30 % of PG cases.2 Pathergy in PG characteristically occurs around surgical sites such as planned ostia formations in IBD patients and breast reconstructions. Subtle trauma may induce pathergy classically in sites of IV insertions and sites of intralesional corticosteroid therapy.Idiopathic PG is a diagnosis of exclusion. When PG is suspected by physical exam, it is imperative to obtain a detailed history to identify or otherwise rule out comorbidities. Standard laboratory evaluation includes a complete blood count, complete metabolic panel with liver function tests, serum, and urine protein electrophoresis, free light chain assay, rheumatoid factor, anti-nuclear antibodies, anti-phospholipid antibodies, HIV serology studies, mycobacterial studies, and a gastrointestinal workup for IBD. A wedge biopsy at the periphery of the ulcer should be performed to sample the ulcer, its margin, and nearby uninvolved skin. Careful planning of the biopsy site with diligence to minimize biopsy size is essential to mitigate the chances of pathergy. However, enough tissue should be obtained for special dermatopathology stains to rule out infectious processes.Treatment of PG has been difficult for several reasons including the lack of gold standard treatments and universal therapeutic protocols. There are currently no FDA approved therapies for PG. Only two randomized controlled trials have evaluated treatments for PG. Anti-tumor-necrosis-factor-α (TNF- α) therapy in the form of infliximab infusion and cyclosporine have both been deemed effective in the treatment of PG. Other TNF-antagonist studies
