Pyoderma gangrenosum (PG) is a rare entity that is characterized by infiltration of neutrophils into the dermis, causing the formation of rapidly enlarging, painful and necrotic skin ulcers. The pathophysiology of PG is still poorly understood. However, genetic, autoimmune and autoinflammatory mechanisms have been proposed that could potentially explain the etiology of this ulcerating skin disorder. Early diagnosis and treatment are key, as the disease course is rapidly progressive and can leave disfiguring, cribriform scars. However, the diagnosis of PG proves difficult, firstly because there are multiple variants of the disease and secondly because it is a clinical diagnosis and can appear similar to that of other diseases such as vasculitis, skin/soft tissue infections and malignancy. Additionally, there are no official diagnostic criteria to aid in the recognition of PG, which often leads to significant delays in diagnosis. The treatment of PG consists in immunosuppression. However, due to a lack of standardized guidelines, therapeutic regimens are usually dependent upon the individual clinician’s experience and are based on little evidence. Knowledge of the clinical features and pathophysiology of PG can aid in early diagnosis and targeted treatment strategies, which in turn results in improved patient outcomes.