Clinical Features of Neutrophilic Dermatosis Variants Resembling Necrotizing Fasciitis

Question  What are the key characteristics of necrotizing neutrophilic dermatosis?

Findings  In this case series involving 6 previously unreported patients with necrotizing neutrophilic dermatitis and a literature review involving 48 patients with necrotizing neutrophilic dermatosis, patients with pyoderma gangrenosum or Sweet syndrome had clinical features that mimicked severe infection, including fever, elevated inflammatory markers, leukemoid reaction, and shock. Debridements and amputations occurred, and antibiotics were prescribed with inadequate treatment response, but all patients responded to immunosuppressive treatment.

Meaning  Pyoderma gangrenosum and Sweet syndrome with prominent systemic inflammation define a subset of neutrophilic dermatoses, termed necrotizing neutrophilic dermatoses, which is frequently misdiagnosed as necrotizing fasciitis; its proper recognition may minimize morbidity associated with delayed or inappropriate treatment.

Importance  Pyoderma gangrenosum and necrotizing Sweet syndrome are diagnostically challenging variants of neutrophilic dermatosis that can clinically mimic the cutaneous and systemic features of necrotizing fasciitis. Improved characterization of these rare variants is needed, as improper diagnosis may lead to inappropriate or delayed treatment and the potential for morbidity.

Objective  To determine the characteristics of necrotizing neutrophilic dermatosis to improve diagnostic accuracy and distinguish from infection.

Design, Setting, and Participants  A case series of patients with necrotizing neutrophilic dermatosis treated at 3 academic hospitals (University of California San Francisco, Oregon Health and Science University, and University of Minnesota) from January 1, 2015, to December 31, 2017, was performed along with a literature review of related articles published between January 1, 1980, and December 31, 2017. Data were obtained from medical records as well as Medline and Embase databases. All patients had signs resembling necrotizing infection and had a final diagnosis of pyoderma gangrenosum with systemic features or necrotizing Sweet syndrome. Patients were excluded if a diagnosis other than neutrophilic dermatosis was made, if key clinical information was missing, and if reported in a non-English language.

Main Outcomes and Measures  Description of key characteristics of necrotizing neutrophilic dermatosis.

Results  Overall, 54 patients with necrotizing neutrophilic dermatosis were included, of which 40 had pyoderma gangrenosum with systemic features and 14 had necrotizing Sweet syndrome. Of the 54 patients, 29 (54%) were male and 25 (46%) were female, with a mean (SD) age of 51 (19) years. Skin lesions commonly occurred on the lower (19 [35%]) and upper (13 [24%]) extremities and developed after a surgical procedure (22 [41%]) or skin trauma (10 [19%]). Shock was reported in 14 patients (26%), and leukemoid reaction was seen in 15 patients (28%). Of the patients with necrotizing neutrophilic dermatosis, 51 (94%) were initially misdiagnosed as necrotizing fasciitis and subsequently received inappropriate treatment. Debridement was performed in 42 patients (78%), with a mean (SD) of 2 (2 [range, 1-12]) debridements per patient. Four amputations (7%) were performed. Forty-nine patients (91%) received antibiotics when necrotizing neutrophilic dermatosis was misdiagnosed as an infection, and 50 patients (93%) received systemic corticosteroids; all patients responded to immunosuppressants.

Conclusions and Relevance  A complex spectrum of clinical findings of pyoderma gangrenosum and Sweet syndrome with prominent systemic inflammation exists that defines a new subset of neutrophilic dermatoses, termed necrotizing neutrophilic dermatoses; recognizing the difference between this variant and severe infection may prevent unnecessary surgical procedures and prolonged disease morbidity associated with a misdiagnosis and may expedite appropriate medical management.