A 56-year-old male with a history of seropositive rheumatoid arthritis complained of polyarthritis and forgetfulness. The initial CT scan of the head without contrast was negative for acute pathologies. However, as he continued to decline despite being on oral prednisone, an MRI of the head was ordered and revealed a subtle small region of acute infarction in the left mammillary body. He was diagnosed with granulomatosis with polyangiitis in light of his positive C-ANCA antibodies, PR3 antibody, and a kidney biopsy, which showed focal necrotizing pauci-immune crescentic glomerulonephritis. Despite undergoing steroid pulse therapy, the patient developed diffuse alveolar damage which finally responded to rituximab infusion.