Clinical Characteristics, Treatments, and Outcomes of Pyoderma Gangrenosum of the Face: A Systematic Review

Pyoderma gangrenosum (PG) is a painful neutrophilic dermatosis typically presenting as an ulceration on the lower extremities in around 80% of cases [1, 2]. However, PG involving the face is uncommon and lacks characteristic distinguishing features, presenting a diagnostic and therapeutic challenge for clinicians. Further, PG primarily involving the mucosae is relatively rare, supporting the hypothesis that PG is a T-cell-mediated disease and that destruction of pilosebaceous units by autoreactive T-cells targeting adnexal structures may play an important role in the pathogenesis [3]. This systematic review examines the literature about facial PG (FPG) to better characterise its clinical features, comorbidities, treatments and patient outcomes. Following the PRISMA guidelines (PROSPERO CRD42023464288), Scopus, Embase and PubMed databases were comprehensively searched for studies, including case reports, case series, clinical challenges and retrospective chart reviews involving FPG, with substantial information for extraction on clinical presentation, associated diseases, diagnostic modalities, treatment strategies and patient outcomes. Only studies with a clinical diagnosis of PG that reported a proper method of exclusion of differential diagnoses (PARACELSUS score, histology, tissue cultures and laboratory investigations) were included. The PARACELSUS score considers these criteria for PG diagnosis: Progressing disease, Assessment of relevant differential diagnoses, Reddish-violaceous wound border, Amelioration by immunosuppressant drugs, Characteristically irregular (bizarre) ulcer shape, Extreme pain > 4/10 on visual analogue scale, localization of lesion at site of trauma (pathergy phenomenon), suppurative inflammation in histopathology, undermined wound border and systemic disease associated [4]. Studies with paediatric cases, PG only involving oral, nasal or ocular mucosae, and retrospective cohort studies lacking data on individual patients were excluded. Two authors independently performed article screening, data extraction, and quality assessments. The final review included 77 out of 1065 studies. The PRISMA flowchart (Figure S1) outlines the screening process. The risk of bias for included studies assessed with the Newcastle Ottawa scale and Joanna Briggs Institute checklists was low (Tables S1–S3). The mean age of patients with FPG was 52 years (SD ± 19) at the time of PG diagnosis. There was a slight female predominance of cases (54.76%). The majority (66.67%) had multiple PG wounds on the face. 65.48% showed exclusive facial involvement. The most prevalent subtype was ulcerative (40.48%). Pathergy was noted in 30.95% of cases. 59.52% had an identified systemic disease. The most common comorbidities included inflammatory bowel disease (IBD) [22.61%], mainly ulcerative colitis (UC) [13.09%] and haematological malignancies (10.71%) [Table 1]. Infection (73.80%) was the most frequent initial diagnosis considered, followed by malignancy (22.61%) and vasculitis (11.90%). Histologically, many diverse findings were observed, with the most common finding being neutrophilic infiltration (48.8%), but a minority of the biopsies showed mixed inflammation (21.42%). The most common treatment modality was systemic treatment (88.10%), which included corticosteroids (82.14%), cyclosporine (25.00%) and dapsone (13.1%). Around 61.90% of cases achieved complete resolution of PG, but 17.30% had recurrence. Treatments caused adverse events in 13.09% of cases (Table 2). FPG is a rare dermatological pathology that can be easily misdiagnosed and hence presents difficulties with treatment [5]. Like typical PG on extremities, FPG also presents as an ulcerative lesion in patients with comorbidities, mainly IBD, and displays primarily neutrophilic infiltration [6, 7]. However, unlike non-facial PG, which typically presents as an ulcerative form in approximately 85% of cases, FPG has a variable presentation, presenting as the typical ulcerative form in only 40.48% of cases and superficial granulomatous subtype as the other predominant form (19.05%) [8]. Moreover, UC (13.09%) was the predominant associated IBD (22.61%) type compared to Crohn's disease in non-facial PG [7]. FPG is also often treated with systemic corticosteroids, as reflected by data from published studies, but many individuals have delayed resolution and recurrence. The disease burden in a visible location is high. To prevent complications and improve patient outcomes, it is essential to recognise FPG early for timely intervention. Limitations include the retrospective nature of the study, small sample size, heterogeneity of cases, publication bias and incomplete data in some studies. Hence, further studies should be performed to optimise treatment protocols and evaluate the impact of location on disease-related quality of life [9]. The authors have nothing to report. We performed a systematic review of the published studies; thus, Institutional Ethics Board Approval was not obtained for this study. The authors declare no conflicts of interest. The authors have nothing to report. Data S1. Figure S1. PRISMA flow diagram detailing the screening process for systematic review of clinical characteristics, treatments, and outcomes of pyoderma gangrenosum of the Face. Table S1. Risk of bias assessment of included case reports. Table S2. Risk of bias assessment of included case series. Table S3. Risk of bias assessment of included retrospective studies. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

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