Pyoderma gangrenosum

Overview

Pyoderma gangrenosum is a disease that causes tissue to become necrotic, causing deep ulcers that usually occur on the legs. When they occur, they can lead to chronic wounds. Ulcers usually initially look like small bug bites or papules, and they progress to larger ulcers. Though the wounds rarely lead to death, they can cause pain and scarring. The disease was identified in 1930. It affects approximately 1 person in 100,000 in the population. Though it can affect people of any age, it mostly affects people in their 40s and 50s.[1]

Causes

Though the etiology is not well understood, the disease is thought to be due to immune system dysfunction, and particularly improper functioning of neutrophils. At least half of all pyoderma gangrenosum patients also suffer from illnesses that affect their systemic function.[1] For instance, ulcerative colitis, Crohn's disease, rheumatoid arthritis, myeloma sufferers have the condition.

Diagnosis

* Infections: * Bacterial, including tuberculosis * Viral, e.g. herpetic ulcers * Parasitic, e.g. syphilis * Tropical mycoses, e.g. sporotrichosis * Vascular: * Arterial or venous ulcers * Vasculitis, e.g. antiphospholipid syndrome, vasculitic rheumatoid arthritis, systemic lupus erythematosus, Wegener's granulomatosis, Behçet's disease * Malignancies: * Squamous cell carcinoma * Cutaneous lymphoma * Insect or spider bites * Sweet's syndrome (fever with erythematous papular eruption; can co-exist with PG)

Treatment

Treatment is non-surgical. The necrotic tissue should be gently removed. Wide surgical debridement should be avoided because it may result in enlargement of the ulcer. Often conventional antibiotics such as flucloxacillin are prescribed prior to making the correct diagnosis. These may be continued if bacteria are cultured in the wound (secondary infection) or there is surrounding cellulitis (red hot painful skin), but they are not helpful for uncomplicated pyoderma gangrenosum. Small ulcers are best treated with: * Potent topical steroid creams * Intralesional steroid injections * Special dressings eg. silver sulfadiazine cream or hydrocolloids. * Oral anti-inflammatory antibiotics such as dapsone or minocycline. * If tolerated, careful compression bandaging for swollen legs * Potassium iodide solution More severe disease requires immunosuppressive therapy: * Tacrolimus ointment is an immune modulating drug that inhibits calcineurin and has been reported to improve pyoderma gangrenosum. It is not yet available in New Zealand (2005). * Oral steroids. These have important side effects and should be taken carefully according to the doctor's instructions. They may be required for several months in high dose. * Ciclosporin. This does not have PHARMAC funding in New Zealand for this indication. It also has important side effects. * Methotrexate. * Cyclophosphamide . * Mycophenolate mofetil. Treatment with the biological agent infliximab has also been reported to be effective.