Awareness of pyoderma gangrenosum is quite variable outside dermatology including among surgeons who come in contact with it as unexplained post-surgical wound breakdown.
Speaking to the limbic after the ACD ASM 2022, Associate Professor Robert Kelly said pyoderma gangrenosum can be confused with infective ulcers, neoplastic ulcers, calciphylaxis, dermatitis artefacta and arterial ulcers.
“Ultimately you have to make a clinical diagnosis. There is no diagnostic test for it. There is no specific histology for it.”
Associate Professor Kelly, head of clinical dermatology at St Vincent’s Hospital Melbourne, said pyoderma gangrenosum was an inflammatory cutaneous ulceration resulting from a destructive immunopathological process which required immunosuppressive therapy to treat it.
“I think the response to immunosuppressive therapy is also a critical part of the diagnosis. Most have a decisive response so response to therapy is a useful piece of diagnostic information.”
“In most cases you can give systemic prednisolone and you will see improvement in a week or two. You will see the inflammation at the edges of the ulcer go down and pain and discomfort will respond very well.”
“Usually, it will respond within 4-6 weeks of commencing systemic corticosteroids.”
However where the condition has not been recognised as being immune in nature, it can quite easily be mismanaged.
He said injury to the skin can induce or flare pyoderma gangrenosum.
“You see definite pathergy in about 40% of cases so it can initially present as an unexplained wound breakdown and sometimes recurrent unexplained wound breakdown. So surgeons will debride and reclose and it will break down again.”
“The other situation where surgery can come into it is where it’s not diagnosed… For instance there might be an attempt at a flap closure of the defect and it just breaks down and gets worse at each attempt at repairing it surgically,” he said.
“The awareness of pyoderma gangrenosum is a bit patchy and I think there needs to be effort to increase awareness amongst other specialties especially surgical specialties to avoid this situation.”
He said there needs to be a systematic and consistent approach to pyoderma in the surgical curriculum.
“It needs to be prioritised within the surgical curriculum as a significant cause of wound breakdown and the importance of diagnosing it early to prevent adverse outcomes.”
Associate Professor Kelly said the challenge with pyoderma gangrenosum was in controlling the disease while minimising exposure to oral corticosteroids (OCS).
“And so what we do is add in other agents…often combination therapy using agents like mycophenolate, cyclosporin, biologic therapy and IVIG.”
He said very refractory patients might be on several of the agents.
“The main thing we want to reduce is the OCS and the cyclosporin because that can particularly affect blood pressure and renal function. People can’t remain on high doses of cyclosporin either and that is particularly true for older people who are more prone to the side effects of both prednisolone and cyclosporine.”
He said about 50% of ulcers heal within 6 months but some can take as long as 12-18 months.
“Some people can have it for years. It can be very refractory or prone to episodic flares. And it can also recur once it’s healed too so sometimes you do maintain low dose immunosuppression after you’ve healed it in order to prevent recurrence.”
Associate Professor Kelly said the condition required better diagnostic criteria and outcome measures which would also help with the collection of prospective data.
“We are currently working on activity measurements to monitor response to therapy… an activity measurement that could be used in a more standardised way across different centres.”
He said a useful score might include inflammation, thickness and undermining of the border, amount of slough and necrosis at the middle of the ulcer, the amount of granulation, and size parameters such as diameter, area and depth.
Similarly, severity measurements might include size, depth, tendon visibility, pain, slough and necrosis.
A recent review of 118 patients with pyoderma gangrenosum presenting to the tertiary hospital dermatology ulcer clinic in Melbourne found half of the patients had multiple ulcers.
Consistent with other studies, just over half of patients had a known associated systemic disease including inflammatory arthritis (20.3%), inflammatory bowel disease (14.4%), haematological disorder (11.0%) or solid cancer (7.6%).
Obesity was present in 61% of the patients suggesting it may be “a contributing and complicating component.”
The most commonly prescribed treatments were prednisolone (95.8%), with mycophenolate (62.5%) and cyclosporin (28%).
“Early diagnosis was associated with a favourable outcome, whereas late diagnosis frequently led to multiple attempts at surgical repair and adverse outcomes for the patient,” the study said.