Introduction. Pyoderma gangrenosum (PG) is a rare, ulcerative dermatosis that is part of a systemic auto-inflammatory process. The overall incidence of PG is 5.8 per 100 000 individuals and it is associated with an increased mortality rate compared with the general population. Due to the pathergy phenomenon—present in 20% to 30% of cases—traumatic events, such as debridement or surgery, are often avoided in these patients. This report is on the use of negative pressure wound therapy with instillation and dwell time (NPWTi-d) combined with a reticulated open cell foam dressing with through holes (ROCF-CC) to achieve debridement and granulation in a lower extremity PG wound. Case Report. A known patient with history of neuropathic arthritis, systemic lupus erythematosus, and cryoglobulinemic vasculitis presented with worsening of his lower extremity wound including new onset pain, odor, and purulent discharge. Negative pressure wound therapy with instillation and dwell time using a hypochlorous acid solution and a ROCF-CC was initiated. Significant decrease in necrotic tissue was noted by day 4, with improved granulation tissue growth by day 25. No pathergy occurred in this case. Conclusions. The use of NPWTi-d with ROCF-CC demonstrated positive debridement effects on this PG wound.

Pyoderma gangrenosum (PG) is a rare, ulcerative dermatosis that is part of a systemic auto-inflammatory process. The overall incidence of PG is 5.8 per 100 000 individuals and it is associated with an increased mortality rate compared with the general population.¹ Treatment of PG focuses on pharmacotherapy, typically with use of systemic steroids and other anti-inflammatory medications, and wound care. Gentle cleansing combined with topical antimicrobials (as indicated) and maintaining a moist wound environment are basic tenets of wound care for this population.¹ Sharp debridement and surgery are often avoided in these patients due to the risk of pathergy, which occurs in 20% to 30% of cases.²

Negative pressure wound therapy with instillation and dwell time (NPWTi-d) allows topical wound solutions to dwell directly on the wound bed. This assists in cleansing the wound bed, while the subsequent NPWT cycle removes slough and other devitalized tissue, as well as solubilized contaminants.³ Specialized dressings have been developed for use with NPWTi-d. A reticulated open cell foam dressing with through holes (ROCF-CC) is one option that can remove infectious materials and thick wound exudate. This may be especially helpful in wounds where debridement is not possible or needs to be delayed.⁴

Hypochlorous acid is a topical wound cleansing solution that is non-cytotoxic and provides an antimicrobial effect.⁵ It may assist in treating wounds that are critically colonized or infected.

This case report presents the use of NPWTi-d (V.A.C. VERAFLO; 3M + KCI) with a ROCF-CC dressing (V.A.C. VERAFLO CLEANSE CHOICE DRESSING; 3M+KCI) and a hypochlorous acid wound solution (Vashe Wound Solution; URGO Medical) to treat a lower extremity PG wound.

A 51-year-old man with a history of neuropathic arthritis, systemic lupus erythematosus, and cryoglobulinemic vasculitis presented with worsening of a wound to the the left lower tibia. The patient reported increasing pain, odor, and purulent discharge over the last 7 days. The patient denied fever but did report feeling “cold” and experienced night sweats and emesis the day before admission. The initial assessment revealed posterior tibialis and dorsalis pedis pulses detectable by hand-held Doppler ultrasound. There was a strong, foul odor present status-post wound cleansing. Initial wound measurements were 14.7 cm x 7.4 cm x 0.6 cm. There was exposed anterior tibialis tendon in the wound and about 90% necrotic tissue present (Figure 1). An MRI scan performed on the day of hospital admission showed no evidence of osteomyelitis.

Wound culture showed 1+ Haemophilus parainfluenzae, and beta-lactamase-negative, rare Corynebacterium species. The white blood cell count was low at 3.76 x 10⁹/L and inflammatory markers were elevated with a C-reactive protein of 57.1 mg/dL and erythrocyte sedimentation rate being 150 mm/hour. The patient was placed on broad-spectrum intravenous (IV) antibiotics to address infection. Systemic steroids were continued, and IV immunoglobulin therapy was provided to address inflammation. Two 4-mm punch biopsies were obtained from the superior wound border and the pathology report stated that “an atypical form of pyoderma gangrenosum cannot be excluded.” Correlation with clinical findings was recommended as well as avoidance of surgical debridement to avoid further expansion of the wound.

Based on the amount of necrotic tissue in the wound, exposed tendon present, and proximity to the tibia, NPWTi-d with ROCF-CC and a hypochlorous acid solution was initiated. For instillation, 14 mL of hypochlorous acid solution was instilled every 2 hours with a 5-minute dwell time. The negative pressure was set at -75 mm Hg continuous pressure and a double layer of petroleum jelly-infused gauze was placed over the exposed tendon for protection. This lower pressure setting was initially chosen in order to assess patient response to the negative pressure and minimize trauma at dressing removal.

Assessment on day 4 showed a significant decrease in necrotic tissue (Figure 2). Odor also decreased, and the wound dimensions demonstrated little change. The NPWTi-d with ROCF-CC and hypochlorous acid solution was continued for an additional 9 days. At that time, treatment was transitioned to NPWTi-d with standard ROCF dressings (Figure 3). Instillation solution, volume, frequency, and dwell time remained the same. Negative pressure was increased to -100 mm Hg continuous pressure.

Wound improvement continued, and on day 25, the wound bed showed significant progression in the amount of granulation tissue (Figure 4) and measured 14.9 cm x 7.5 cm x 0.5 cm. Wound coverage with a cellular- and/or tissue-based product (CTP) was planned as the next step in the wound closure process.

To the best of the author’s knowledge, this is the first report on the specific use of NPWTi-d with ROCF-CC to treat a PG wound. There is evidence to support that normal saline instillation may be as effective as antiseptic solutions with NPWTi-d.⁶ However, due to the systemic signs of infection, amount of necrotic tissue, and exposed structures present in this case, an antimicrobial solution was selected as an adjunct treatment modality. Further research is needed to assess efficacy of different cleansing solutions with NPWTi-d across patient scenarios.

Very few case reports currently exist regarding the use of NPWT (standard or portable devices) with PG. In these cases, there has been concern that NPWT stimulation might trigger pathergy or new lesions.^7-9 In this patient case, a lower negative pressure setting was used initially and titrated up based on wound response. Whether this contributed to the lack of pathergy in this case or is a necessary aspect of NPWT in PG remains to be seen.

Typically, in a 25-day period, one would expect to see a substantial decrease in wound size. Although that was not seen in this case, the stability of the wound measurements demonstrates that pathergy did not occur. This is notable considering the amount of necrotic tissue that was removed. The NPWTi-d and ROCF-CC intervention also achieved adequate wound bed preparation for coverage with a CTP.

The location of the wound in this case (left lower tibia) worked well for applying NPWTi-d without any issues in managing the seal of the device to the site. The ROCF-CC dressing in particular did seem to contribute to the debridement effect that was noted.

This case suggests that NPWTi-d with ROCF-CC can effectively debride a PG wound without causing pathergy. This may provide an additional intervention strategy for these difficult-to-treat wounds. As this is a single case study, further research is required to determine the benefit of NPWTi-d with ROCF-CC for the management of PG.

Author: Stephanie L. Woelfel, PT, DPT, CWS

Affiliation: Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA

Correspondence: Stephanie L. Woelfel, PT, DPT, CWS,  Assistant Professor of Clinical Physical Therapy and Surgery, Division of Biokinesiology and Physical Therapy, University of Southern California, 1500 San Pablo Street, 3rd Floor, Los Angeles, CA 90033-9006; stephanie.woelfel@med.usc.edu

Disclosure: The author discloses no financial or other conflicts of interest.