PracticeUpdate Dermatology February 2019

EDITOR’S PICKS 14

Clinical Features of Neutrophilic Dermatosis Variants Resembling Necrotizing Fasciitis JAMA Dermatology Take-home message • The authors report a case series of 54 patients with necrotizing neutrophilic der- matosis (NDD), with either pyoderma gangrenosum with systemic features (n=40) or necrotizing Sweet syndrome (n=14), to describe the key characteristics of this newly defined dermatosis and propose clinical criteria for diagnosis. Of the 54 patients, 51 (94%) were initially misdiagnosed with necrotizing fasciitis (NF), leading to many receiving an inappropriate treatment with debridement (78%), amputation (7%), or antibiotics (91%). Common clinical features were erythema, ulcers, and necrosis. Skin lesions commonly occurred on the extremities and developed after a surgery or skin trauma. Many patients had clinical features that mimicked severe infection, including fever (67%), elevated inflammatory markers (43%), leukocytosis (67%), and shock (26%). Patients largely had neutrophilic inflammation on histopathology, sterile tissue cultures, lack of response to antibiotics, and improvement with systemic steroids. • Necrotizing neutrophilic dermatosis is a part of the spectrum of classic neutrophilic dermatoses and yet is a distinct variant. Clinical morphology, tissue biopsy, and culture are critical for differentiating NDD from NF, and, while the authors proposed clinical criteria for diagnosis, further refinement is needed. Caroline K. Crabtree MD

Abstract IMPORTANCE Pyoderma gangrenosum and necrotizing Sweet syndrome are diagnostically challenging variants of neutrophilic derma- tosis that can clinically mimic the cutaneous and systemic features of necrotizing fasciitis. Improved characterization of these rare vari- ants 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 derma- tosis treated at 3 academic hospitals (University of California San Francisco, Oregon Health and

COMMENT By Lindy Fox MD T hese authors assessed 54 patients (comprised of 6 patients from three academic centers and 48 patients identified from a review of the literature) who presented with neutro- philic disorders that mimicked necrotizing fasciitis. The authors proposed the term neutrophilic necrotizing dermatoses to better characterize and categorize this subset of patients with pyo- derma gangrenosum or Sweets syndrome who present with skin lesions with rapid necrosis accompanied by systemic mark- ers of inflammation that mimic sepsis. Overall, 94% of patients in the study were misdiagnosed as having necrotizing fasciitis. The most common underlying diseases were hematologic disor- ders (33%). Lesions presented as erythema, ulcers, or necrosis, most commonly located on the extremities. In all, 67% of patients presented with fever and 26% presented with signs of sepsis. A total of 95% of patients had a leukocytosis or leukemoid reac- tion. Overall, 94% of patients underwent a skin biopsy, and, in 43% of cases, the neutrophilic inflammation extended down into muscle or fascia. Tissue cultures were negative in 98% of the 45 patients from whom they were collected. A total of 78% of patients underwent surgical debridement, and 7% of patients " Recognition of these extreme presentations, especially by non-dermatologists, is critical as the correct diagnosis moves the intervention from debridement and possible amputation to systemic immunosuppression. "

underwent limb amputation. All patients responded to immuno- suppression, most commonly systemic steroids. This paper is important in that it highlights a severe cutaneous presentation of neutrophilic diseases that morphologically and systemically mimics necrotizing fasciitis. Although it is well- appreciated among dermatologists that neutrophilic diseases can mimic infections, severe sepsis-like presentations of neutrophilic diseases are rarer. Recognition of these extreme presentations, especially by non-dermatologists, is critical as the correct diagnosis moves the intervention from debridement and possible amputation to systemic immunosuppression. As the subspecialty of inpatient dermatology develops and manpower increases, consultation by an inpatient dermatologist on cases such as these becomes increasingly relevant.

Dr. Fox is Associate Professor of Clinical Dermatology, Director of Hospital Consultation Service, and Director of Complex Medical Dermatology Fellowship in the Department of Dermatology, University of California in San Francisco, California.

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