An Unusual Presentation of Blastomycosis-Like Pyoderma Gangrenosum

Pyoderma gangrenosum (PG) is a rare, neutrophil-mediated ulcerative cutaneous disorder characterized by painful skin ulcerations.¹ The estimated incidence of PG is about 3 to 10 cases per 1 million people per year.^2,3 Most cases are associated with underlying systemic disease (eg, inflammatory bowel disease [IBD]), and females are affected more often than males. Typically, PG presents as an ulceration of the skin with a central area of necrosis surrounded by inflammatory cell infiltrates. Management of PG mainly includes topical or systemic anti-inflammatory treatment and wound care.⁴ The unclear presentation of PG warrants consideration of many varied diseases before making a final diagnosis of PG, which is usually a diagnosis of exclusion.⁵ 

Several subtypes of PG exist, and the ulcerative subtype is the most common and classical presentation. The other subtypes include periosteal, vegetative, bullous, and pustular forms.⁴ Therefore, this complex cutaneous disease can present with many clinical features, suggesting the need for an exhaustive history and a physical to consider differential diagnosis to rule out other pathologies. Herein, the authors explore an atypical presentation of PG that at different stages of treatment mimicked various other cutaneous diseases including maligancy. Owing to the varied methods of optimal treatment of cutaneous diseases based on the etiology, careful consideration is necessary to make the correct diagnosis.

A 74-year-old female patient was referred to the ProMedica Jobst Vascular Institute in Toledo, Ohio. The patient had a history of venous insufficiency but no history of IBD or rheumatoid arthritis. The patient was presumed to have squamous cell carcinoma (SCC) on the left lower extremity, with persistently positive margins despite multiple surgical resections (Figure 1A). The patient underwent re-excision at the authors' facility (Figure 1B), after which a hyaluronic acid bilayered matrix (Hyalomatrix; Medline) was applied to the wound bed and negative pressure wound therapy was initiated. Figure 1C shows the appearance of the wound 1 week postoperatively.

The final pathologic reports showed reactive squamous cell hyperplasia and dermal abscess formation with blastomycosis-like PG (Figure 2). A dermatologist was consulted, and the histology was reviewed with a dermatopathologist to confirm the diagnosis. Perioperative doxycycline was begun owing to Staphylococcus cultured from the wound. The patient received high doses of prednisone treatment (40 mg daily), which was tapered gradually and discontinued 2 months later. Four weeks after the initial procedure, the patient was scheduled for a split-thickness skin graft and a negative pressure wound therapy application as a bolster dressing. The patient returned to the clinic 6 days postoperatively, at which time the skin-grafted areas were found to be healing well (Figure 3A). The graft donor site and recipient sites were monitored carefully while the patient was weaned off the steroids. No signs of pathergy were observed 6 months postoperatively (Figure 3B, 3C). A gastroenterologist was consulted, and a colonoscopy revealed no signs of IBD. 

This case study highlights a unique presentation of PG. Although subtypes of PG exist, this case report indicates the necessity and importance of identifying the unique presentations of the disease; doing so requires steadfast investigation and differential consideration for optimal patient safety and outcomes. After diagnosis, PG is usually managed with steroids, although recurrence has been shown in several cases.^6,7

The complexity of this case evolved, as evidenced by the original diagnosis of SCC of the lower extremity. Squamous cell carcinoma is the malignant transformation of epithelial cells.⁸ Few studies have shown mimicry in the presentation of SCC and PG. Wolfe et al⁹ reported on a patient with a hand ulcer that was later diagnosed as SCC after biopsy was performed by hand surgeons. Subsequent biopsy performed by a dermatologist at the peripheral regions of the wound revealed neutrophilic infiltration more representative of PG, resulting in alteration of the course of treatment from amputation to steroid treatment.⁹ Another case report showed conflicting clinical and histologic results in a patient with an ulceration on the hand; those researchers opted for more conservative medical treatment including prednisone, followed by cyclosporine, and finally infliximab, which resulted in successful healing of the ulcer.¹⁰ Rostom et al¹¹ presented the histologic similarities between SCC and the proliferative form of a benign nature of PG. These findings elucidated the need for more rigorous scrutiny in histologic analysis to differentiate between malignancy and benign proliferation.¹¹ These study findings identify the importance of the location of sample biopsy in addition to that of establishing conservative treatment measures early based on clinical acumen (ie, steroids vs surgery).

Pyoderma gangrenosum has also been shown to mimic fungal disorders. Blastomycosis is a fungal disease endemic to the Ohio and Mississippi River Valleys and usually presents with upper respiratory and flu-like symptoms, although it is usually self-resolving.¹² Infection with specific Blastomyces dermatitidis species results in cutaneous papules with a central clearing or ulceration.¹² In cases of mild or moderate disease, the usual treatment for blastomycosis is azoles, such as ketoconazole.¹³ The skin is the most common extrapulmonary distribution of blastomycosis, with such distribution occurring in up to 40% to 80% of patients with the disease.¹⁴ Several case studies have reported blastomycosis presenting as PG,^15-17 which highlights the urgent need for careful consideration of diagnoses to ensure appropriate treatment. 

One limitation of this case report is the individuality of this presentation of PG. Rare presentations of diseases such as PG can complicate and confuse health care providers in terms of their confidence in a particular diagnosis early in treatment. In addition, the lack of well-defined criteria for biopsy makes diagnosis difficult. It is recommended to perform multiple biopsies to include the center and the edges of the lesion. Both types of biopsy can present varied histologic features that can drive treatment in various directions (immunologic treatment vs fungal treatment vs surgery). In future clinical practice, early and accurate diagnosis of PG will contribute to a larger series that would allow for a broader characterization of the diagnostic features of PG and provide a more timely diagnosis of the disease. 

To limit the clinical course of patients with abnormal wounds, as in the case study presented here, physicians should consider the presence of PG, perform a biopsy, and consult with a multidisciplinary team for interpretations and confirmation (ie, dermatologist, dermatopathologist, plastic surgeon). Once the diagnosis is confirmed, steroid therapy and wound healing modalities must be initiated. In severe cases, a second immunomodulating therapy may be added with the input of a rheumatologist, which may limit the disease progression and improve the outcome. 

Authors: Richard Simman, MD, FACS, FACCWS^1,2,3; Darren Gordon, PhD³; Mary Steven, DNP²; and Amy Lynn, MD⁴

Affiliations: ¹Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH; ²Jobst Vascular Institute, ProMedica Health Network, Toledo, OH; ³University of Toledo, College of Medicine and Life Sciences, Toledo, OH; ⁴ProMedica Flower Hospital, Department of Pathology, Sylvania, OH 

Correspondence: Richard Simman, MD, FACS, FACCWS, Director of Wound Care, ProMedica Toledo Hospital, Jobst Vascular Institute, 2109 Hughes Drive, Suite 400, Toledo, OH 43606; richardsimman@hotmail.com; richard.simmanmd@promedica.org 

Disclosure: The authors disclose no financial or other conflicts of interest.