Explosive Granulomatosis with Polyangiitis Mimicking Infective Endocarditis

Background: Granulomatosis with polyangiitis (GPA) is a rare systemic disease that causes necrotizing granulomatous inflammation of small- and medium-sized blood vessels. Infective endocarditis (IE), which is a disease due to infection of the innermost surface of the heart, is pathophysiologically distinct from GPA and yet these two entities can manifest in strikingly similar ways. Case presentation: We report a case of a 46-year-old male whose presentation and history were strikingly suggestive of IE but was ultimately diagnosed with GPA. Originally, he presented with fever, oral ulcers, and purpuric lesions on the extremities. The patient had a history of illicit drug use and had recently undergone a dental procedure one week prior to presentation, which were classic risk factors for IE. His fever and respiratory difficulty were unresponsive to antibiotic therapy. His respiratory and renal status declined explosively during his hospitalization, requiring intubation and intensive level care. His clinical progression, negative blood cultures, and a positive c-ANCA screen prompted a workup that was more consistent with GPA. Administration of anti-inflammatory medications and plasmapheresis eventually lead to the resolution of his symptoms. Because of his precipitous pulmonary decline, his outcome would have been poor if the correct diagnosis of GPA were to have been overlooked. Conclusions: ANCA-associated vasculitis and infective endocarditis can demonstrate similar clinical findings, including in the skin. Overlap in serologic markers and other organ involvement can lead to difficulty in distinguishing these two diseases, which require contrasting treatment methods. We highlight and compare the similarities and differences between GPA and IE in discussion of this interesting case to emphasize the importance of being clinically vigilant in differentiating these two separate disease processes.