Understanding the Zebras of Wound Care: An Overview of Atypical Wounds

Elizabeth Ansert, DPM, MBA, MA; Anthony Tickner, DPM, FACCWS, FAPWCA, FAPWH; Donald Cohen, DPM; Weldon Murry, DPM; Samuel Gorelik, DPM


Wounds. 2022;34(5):124-134. 

In This Article

Pyoderma Gangrenosum

Pyoderma gangrenosum (PG) is a relatively uncommon dermatosis of neutrophilic origin. It often presents as an ulcerative skin disorder, with accompanying inflammation. It most commonly presents as a papular or pustular distribution with violaceous undermined borders or as the result of pathergy (Figure 1). Pyoderma gangrenosum ulceration often has a purulent base with exuberant amounts of discharge.

Figure 1.

Pyoderma gangrenosum (PG) in a patient who noted the presence of ulcerations after experiencing the inside of his shoes rubbing against his skin. This figure illustrates the bluish, indurated borders of the wound, which are characteristic of ulcerative PG.

Pyoderma gangrenosum presents in 3 to 10 per 1 million people per year.[9] It can affect anyone from childhood through adulthood; however, women are more frequently affected than men. Most of those individuals in whom PG develops also have an underlying condition such as inflammatory bowel disease, arthritis, or various hematologic disorders.[10] The exact mechanism of PG remains unclear, although neutrophil dysfunction, genetic factors, and systemic inflammation may play a role. Neutrophils are the prominent cell type in pathologic specimens.[11–13] Pyoderma gangrenosum is a diagnosis of exclusion; often, tissue biopsies show only acute and chronic inflammatory changes.

Pyoderma gangrenosum clinically manifests in various ways and is often classified into 4 subtypes: ulcerative (typical), bullous (atypical), pustular, and vegetative (superficial granulomatous). Ulcerative, or typical, PG begins as a tender papule, vesicle, or pustule.[10] It typically appears at the site of trauma but may also appear on normal skin. It most commonly occurs in the lower extremities or the trunk. The edges of the area of ulceration usually are described as being bluish and are typically undermined. The ulcer base appears necrotic and purulent into subcutaneous fat or fascia. Resolution of these ulcers tends to lead to scar formation.[10]

Bullous, or atypical, PG is much less common than ulcerative PG. Bullous PG often affects the face and upper extremities. Affected persons present with a blue or blue-gray bulla that progresses to a superficial spreading ulcer to the affected areas. A strong association exists between bullous PG and hematologic disease.[14,15]

Pustular PG arises during acute exacerbation of inflammatory bowel disease. Affected patients typically present with an eruption of painful, erythematous pustule formations, as well as fever and joint pain.[10,16] Vegetative PG presents as a mildly painful nodule, plaque, or ulcer and is often indolent. It is often similar in appearance to verrucae. The difference between verrucae and vegetative PG is that vegetative PG lacks undermining borders and purulent bases and often affects the head and neck.[10]

Management of PG typically consists of localized wound care, including normal saline or mild antiseptic cleansing before dressing changes. Promotion of a moist wound environment without the dressing sticking to the base is necessary because of the pain experienced with these wound types. A typical dressing for PG includes alginates on the surrounding skin to avoid maceration in combination with absorptive dressings overlying the base. The use of wet-to-dry dressings, debridement, caustic substances (eg, silver nitrate), or any other type of dressing that would cause wound pathergy must be avoided.[17,18] The application of topical corticosteroids to surrounding wound areas to decrease inflammation has been suggested, but this idea is supported by very few retrospective studies.[19,20] The topical steroid used must be high potency (eg, clobetasol propionate) and should be applied twice daily to affected areas and used as an adjunct to other local wound care.[19,20] Cellular- and tissue-based products are increasingly being used in the management of PG. Chan et al[21] described the use of surgical debridement followed by application of fetal bovine tissue to provide a wound bed with well-vascularized tissue. Debridement is important for successful healing and is becoming increasingly common in the surgical management of PG. The use of cadaver allograft results in integration of the graft and carries a lesser risk compared with the risk associated with harvesting autografts.[22] Pharmacologic use of dapsone (an antineutrophilic agent), cyclosporine, and tumor necrosis factor alpha (TNF-α) inhibitors has also shown to be an effective adjunctive therapy to local wound care. Few studies have been done on the use of TNF-α inhibitors in the management of PG, but significant improvement was reported in a case series of 4 patients with PG.[23] Referral to a pain management specialist should be considered if a patient has pain out of proportion to the clinical presentation of the ulceration.[19,24,25]