GRANULOMATOSIS WITH POLYANGIITIS PRESENTING AS CROHN’S DISEASE: A DIAGNOSTIC CHALLENGE CASE REPORT

Background Granulomatosis with polyangiitis is a rare systemic ANCA associated vasculitis that typically involves the upper respiratory tract, lungs, and kidneys. Gastrointestinal manifestations are uncommon and may lead to diagnostic confusion with inflammatory bowel diseases, particularly Crohn’s disease. Aims To present a diagnostically challenging clinical case of granulomatosis with polyangiitis with predominant gastrointestinal manifestations mimicking Crohn’s disease and to highlight the role of serological and histopathological assessment in establishing the correct diagnosis. Methods A detailed clinical evaluation was performed including laboratory testing, endoscopic examinations, cross sectional imaging, and histopathological analysis. Serological testing for ANCA was conducted, and the patient was assessed by a multidisciplinary team. Results A 37 year old female presented with bloody diarrhea, hematemesis, abdominal pain, arthralgia, and oral ulcerations. Endoscopic and radiological findings suggested Crohn’s disease with segmental small bowel wall thickening and multiple gastric and colonic ulcers. Laboratory evaluation revealed anemia, leukocytosis, elevated inflammatory markers, and markedly elevated PR3 ANCA levels. Histopathological examination demonstrated chronic active inflammation consistent with vasculitis. The final diagnosis of granulomatosis with polyangiitis was established. Conclusions Granulomatosis with polyangiitis may present with predominant gastrointestinal involvement closely resembling inflammatory bowel disease. In patients with atypical gastrointestinal manifestations and systemic features, ANCA associated vasculitis should be considered, and extended serological and histopathological diagnostics are essential to avoid delayed or inappropriate treatment.