Granulomatosis with polyangiitis and skin ulcers mimicking pyoderma gangrenosum: Case report of a diagnostic challenge

Introduction: Granulomatosis with polyangiitis (GPA) and pyoderma gangrenosum are rare and difficult-to-diagnose pathologies with severe manifestations and a high burden of morbidity. GPA is a necrotizing systemic vasculitis of small vessels, while pyoderma gangrenosum is an inflammatory skin disease. Objectives: The aim of this study is to describe the comprehensive clinical-pathological study process necessary to accurately identify these conditions and establish an effective treatment plan. Materials and methods: A retrospective study was conducted on a case of a patient with cutaneous lesions suspected of pyoderma gangrenosum. Clinical data, including symptoms, laboratory tests, biopsies, and imaging results, were collected. A multidisciplinary review of the findings was carried out to reach an accurate diagnosis. The treatment consisted of administering methotrexate. Results: Following the comprehensive clinical-pathological study, the diagnosis of granulomatosis with polyangiitis associated with pyoderma gangrenosum-like lesions was confirmed. The patient responded favourably to methotrexate treatment, and the cutaneous lesions completely resolved after one year. Conclusions: This case illustrates the difficulty in diagnosing granulomatosis with polyangiitis and pyoderma gangrenosum, highlighting the importance of a multidisciplinary approach in their management. The comprehensive clinical-pathological study and appropriate treatment led to successful resolution of the patient's lesions. It is crucial to promote collaboration among different medical specialties to improve the diagnosis and treatment of these rare and highly morbid diseases.