Pyoderma Gangrenosum of the Genitalia, Anus, and Perineum: Two Case Reports and a Review of Published Cases.

ABSTRACT: Pyoderma gangrenosum is an inflammatory skin disease that presents with rapidly progressive ulcers with violaceous, undermined borders. Despite most commonly affecting the lower extremities, pyoderma gangrenosum can rarely present in the genital, anal, and perineal regions. We describe 2 cases and report a review of published cases.

Human Inborn Errors of Immunity in Pyoderma Gangrenosum: A Systematic Review.

BACKGROUND AND OBJECTIVE: Pyoderma gangrenosum (PG) is a rare ulcerative neutrophilic dermatosis that can be associated with primary immunodeficiency. The pathogenesis of PG has not yet been elucidated, although contributions from dysregulation of the immune system in patients with apparent genetic predispositions have been postulated. We conducted a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided systematic review with the objective of identifying inborn errors of immunity in the presence of PG as well as their clinical characteristics of severity including number of PG lesions and anatomic areas affected, and treatment outcomes. METHODS: A literature search was performed using PubMed/MEDLINE, Embase, Cochrane Library, and Web of Science through August 24, 2023, for studies published in English using the search terms: "pyoderma gangrenosum," "inborn error of immunity," "immune defect*," and a list of genetic mutations potentially associated with PG. RESULTS: Seventy-four cases of PG associated with inborn errors of immunity were identified. The results demonstrate an association of PG with a variety of inborn errors of immunity, including genetic mutations not classically associated with the condition. Genetic mutations such as BTK, IL1RN, ITGB2, LPIN2, MEFV, NFkB1, NLRP3, NLRP12, NOD2, PSMB8, PLCG2, PSTPIP1, RAG1, TTC37, and WDR1, as well as complement component 2/complement component 4 (C2/C4) and complement component 7 (C7) deficiencies were identified in the presence of either idiopathic or syndromic PG. Of note, mutations in genes such as PSMB8, NLRP3, and IL1RN were found to be associated with a more severe and atypical course of PG, whereas mutations in RAG1 as well as those causing a C2/C4 deficiency were associated with the mildest clinical presentations of PG. Mutations in NFkB1, ITGB2, and PSTPIP1 were associated with the most heterogeneous clinical presentations. CONCLUSIONS: Human inborn errors of immunity may be implicated in the genetic predisposition to PG and may influence the clinical presentation. Due to the rarity of these diseases, further work must be done to describe the association between inborn errors of immunity and PG. Identifying inborn errors of immunity that may contribute to the development of PG may assist in further elucidating the mechanism of PG, guiding targeted treatment, and improving clinical outcomes for these patients.

IL-12/IL23 blockade reveals patterns of asynchronous inflammation in pyoderma gangrenosum.

Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis causing chronic and recalcitrant painful ulcerations. Pathogenic mechanisms are yet poorly understood limiting therapeutic options, however, IL-12/IL-23 inhibition via ustekinumab has previously been associated with positive outcomes. We aimed to elucidate the dysregulated immune landscape of PG and lesional skin changes associated with IL-12/IL-23 blockade. We applied spatial transcriptomics and comparative computation analysis on lesional biopsies from two patients obtained before and after IL-12/IL-23 blockade with ustekinumab. Our data indicate lesional PG skin exhibits complex patterns of inflammation, including a not previously described major infiltration of B cells and establishment of tertiary lymphoid structures. In both patients, IL-12/IL-23 blockade led to marked clinical improvement but was associated with amelioration of contrasting inflammatory pathways. Notably, plasma cell markers and tertiary structures were recalcitrant to the treatment regime suggesting that B cells might play a role in the refractory nature of PG.