Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis characterized by painful, nonhealing cutaneous ulcers. Although dysregulated innate immunity and neutrophil activation are implicated in its pathogenesis, the underlying molecular mechanisms remain poorly defined. This study aimed to identify conserved pathogenic mechanisms by integrating analyses of human PG lesions and a brequinar-induced PG-like murine model and to assess therapeutic relevance. Skin biopsy specimens from patients with PG and publicly available RNA-sequencing data were analyzed alongside the murine model using histological and transcriptomic approaches. Cross-species transcriptomic integration identified shared inflammatory pathways between human and murine PG. Human PG lesions showed increased neutrophil infiltration, neutrophil extracellular trap formation, and a dominant type 1 inflammatory profile, all of which were recapitulated in the brequinar-induced mouse model, together with impaired wound healing. Transcriptomic analyses revealed enhanced oxidative stress responses and activation of the NLRP3/caspase-1 inflammasome pathway as a conserved pathogenic axis. In the murine model, both prednisolone and avacopan suppressed inflammatory cytokine expression and neutrophil activation; however, only avacopan significantly improved wound healing. Collectively, these findings suggest that NLRP3 inflammasome activation is associated with type 1 inflammation and neutrophil extracellular trap formation and may represent a PG-associated inflammatory pathway.

To summarize and critically evaluate recent literature on autoinflammatory syndromes of hidradenitis suppurativa (HS).

Post-surgical pyoderma gangrenosum (PPG) is an underdiagnosed variant of a neutrophilic dermatosis that mimics postoperative wound infections, delaying correct diagnosis and treatment. This case series presents 10 female patients who developed PPG following elective aesthetic breast and abdominal surgeries. The average onset of symptoms was 11.4 days postoperatively, with painful ulcerated lesions localized to surgical wounds, often misinterpreted as infection. Diagnosis was primarily clinical and confirmed histologically in 50% of cases. Systemic corticosteroids were the cornerstone of therapy, combined with immunosuppressants in 80% of cases. Hyperbaric oxygen therapy was used in six patients, with excellent clinical response. The average time to clinical resolution was 5.7 months, with no recurrence. Despite successful management, all patients developed unaesthetic scarring. This series reinforces the importance of early suspicion of PPG in atypical postoperative wound evolution and highlights the role of multidisciplinary treatment combining immunosuppression and adjuvant wound care modalities.

Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis that may occur after surgery and mimic wound infection. We report the case of a 30-year-old woman who developed painful progressive ulceration 7 days after caesarean section. Initial treatment with broad-spectrum antibiotics for presumed surgical site infection was ineffective. Clinical examination showed a large hypogastric ulcer with an erythematous base and undermined inflammatory borders. Histopathological examination of a biopsy taken from the ulcer edge demonstrated a dense dermal neutrophilic infiltrate, supporting the diagnosis of PG. Oral prednisolone at 1 mg/kg/day was started, with progressive improvement and complete re-epithelialization after 4 months. This case highlights the importance of considering PG in postoperative wounds that worsen despite adequate antimicrobial treatment, in order to avoid unnecessary surgical procedures and initiate timely immunosuppressive therapy.

A variety of skin conditions may be important diagnostic indicators for disorders of the digestive tract and liver. In inflammatory bowel diseases, the most common cutaneous manifestations are erythema nodosum and pyoderma gangrenosum. Autoimmune liver diseases are often associated with cutaneous manifestations such as hidradenitis suppurativa, vitiligo, psoriasis and alopecia areata. Lichen planus or porphyria cutanea tarda can also be induced by infectious hepatitis. Enteral malabsorption can lead to deficiencies and characteristic skin changes, such as celiac disease, acrodermatitis enteropathica, pellagra and scurvy. In addition, cutaneous sequelae, including various exanthems and adverse reactions, from drug treatment of intestinal and liver diseases are possible. Likewise, so-called paradoxical reactions in which new and previously absent skin conditions (e.g. psoriasis) may also develop, especially following treatment with biological products. Thus, gastroenterologists should recognize and diagnose cutaneous changes that are new or evolving in patients with intestinal and liver diseases in order to initiate appropriate therapy.

Postoperative pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis that frequently masquerades as a surgical site infection. Because its clinical presentation closely resembles postoperative cellulitis or even necrotizing soft tissue infection, diagnosis is often delayed. Misdiagnosis may result in unnecessary antibiotic escalation, repeated surgical interventions, and progressive tissue destruction due to pathergy. This case highlights the importance of early recognition of PG and serves as a reminder for surgeons to consider this uncommon diagnosis when postoperative wounds fail to respond to conventional treatment. A 75-year-old woman underwent elective open varicose vein surgery (ligation of neocrosse veins and phlebectomies) for recurrent symptomatic varicose veins of the left lower limb. One week postoperatively, she developed a painful erythematous wound that was initially diagnosed as a surgical site infection. Despite drainage, repeated wound care, and escalation from oral to broad-spectrum intravenous antibiotic therapy, the lesion rapidly progressed into an extensive necrotic ulcer. Repeated wound cultures and blood cultures remained sterile, while computed tomography scans demonstrated inflammatory changes without evidence of a drainable collection or necrotizing soft tissue infection. Following dermatological consultation, postoperative PG was suspected and confirmed by skin biopsy. High-dose systemic corticosteroid therapy was initiated, resulting in rapid clinical improvement, cessation of ulcer progression, and subsequent wound healing. This case illustrates the diagnostic challenge of postoperative PG and emphasizes several clinical features that should prompt reconsideration of a presumed surgical site infection, including disproportionate pain, rapidly progressive ulceration, sterile cultures, failure of appropriate antimicrobial therapy, and inconclusive imaging findings. Early recognition is essential, as surgical manipulation may exacerbate disease progression through pathergy. Postoperative PG should be considered in any patient presenting with a rapidly progressive postoperative wound that fails to improve despite appropriate antimicrobial treatment. Increased awareness among surgeons may facilitate earlier diagnosis, prevent unnecessary surgical procedures, and reduce the risk of extensive tissue loss.

Pyoderma gangrenosum is a rare neutrophilic dermatosis that presents as rapidly progressive ulcerative lesions, often associated with systemic diseases. Pyoderma gangrenosum remains an uncommon and challenging diagnosis particularly in a pediatric population. We report a 3-year-old male with myelodysplastic syndrome who developed a nonhealing ulcer of the right forearm following minor trauma. The lesion was misdiagnosed as an infection, leading to prolonged antibiotic therapy. The patient underwent surgical debridement and closure of the ulcer with bilateral advancement flaps with biopsies taken. However, the wound dehisced and ulcerated. Due to the progressive nature and lack of response to antimicrobials, pyoderma gangrenosum was suspected and later confirmed through clinical and histopathologic findings. The patient demonstrated significant clinical improvement with 2 months of topical and systemic corticosteroid therapy. This case highlights the challenges of diagnosing pyoderma gangrenosum in pediatric populations, and the utility of histology in management, given the low index of suspicion in children.