Pyoderma Gangrenosum

Key Points
Uncommon skin ulceration which typically affects the legs
Exact cause is unknown, but is thought to be an autoimmune disorder
Initially consists of a bump or blister which then ulcerates, growing rapidly, and is severely painful

Pyoderma gangrenosum is an uncommon skin ulceration which typically affects the lower legs, often in an area which has been subject to trauma. It initially consists of a small bump or blister, red in color, which begins to ulcerate. Lesions grow rapidly, and have a purple border. Tissue in the ulcerated area becomes undermined and the condition is severely painful. Multiple ulcers may appear simultaneously.

Pyoderma gangrenosum is thought to be an autoimmune disorder, in which the body attacks the tissue of the affected area, though its exact cause is unknown. While the condition may affect any age or gender group, it typically appears after age 50. Additionally, persons with other internal condition may be at an increased risk of developing pyoderma gangrenosum. These disorders include inflammatory bowel diseases, rheumatoid arthritis, hepatitis, Wegener granulomatosis, PAPA syndrome, and myeloid blood dyscrasias.

Differential Diagnosis (Other conditions with similar appearance)
Acute Febrile Neutrophilic Dermatosis
Hypersensitivity Vasculitis (Leukocytoclastic Vasculitis)
Aphthous Stomatitis
Impetigo
Behcet disease
Insect Bites
Chancroid
Sporotrichosis
Squamous Cell Carcinoma
Ecthyma
Ecthyma Gangrenosum
Herpes simplex

Diagnosis
Key Points
Diagnosis based on the characteristic appearance of the affected area
Skin biopsy may be performed to rule out other conditions

Pyoderma gangrenosum is typically diagnosed based on the characteristic appearance of the affected area. A skin biopsy may be performed to rule out similar appearing conditions.

Treatment
Treatment is always non-surgical, as surgical removal may worsen the condition
Various treatments are available
Severe cases may require treatment with immunosuppressant therapies

Though necrotic tissue in the affected area should be gently removed, surgical removal or debridement of the area are not effective treatments and may worsen pyoderma gangrenosum. Various treatments may be used on smaller ulcers, including topical steroids, potassium iodide solution, intralesional steroid Injections, anti-inflammatory antibiotic medications, and special dressings such as silver sulfadine, hydrocolloids, and compression bandaging. In more severe cases, immunosuppressant therapies may be utilized, including medications such as tacrolimus, systemic steroids, ciclosporin, methotrexate, cyclophosphamide, mycophenolate mofetil, and Infliximab.