Small Vessel Vasculitis Mimicking Inflammatory Bowel Disease

Proteinase 3 (PR3)-antineutrophil cytoplasmic autoantibody (ANCA) is a necrotizing small vessel vasculitis and the most common subgroup of ANCA-associated vasculitides (AAV). The rarity of these disorders, in conjunction with their variable and often nonspecific presentations, contributes to the diagnostic challenges surrounding AAV. We describe a unique presentation of PR3-AAV, with predominantly gastrointestinal symptoms and a painless penile ulcer, highlighting the overall heterogeneity of disease manifestation with AAV and the importance of maintaining a high index of suspicion for these disorders. Endoscopic findings and renal histopathology, along with a positive PR3-ANCA, were crucial for a timely and accurate diagnosis and treatment.