Abstract
A male patient in his 30s with autism and depression presented to the emergency department with joint pain, a petechial/purpuric rash, sputum production, hemoptysis, and epistaxis. His mother reported a family history of autoimmune conditions. Examination revealed a non-blanching petechial/purpuric rash and tenderness in the feet and ankles. Elevated inflammatory markers, non-blanching rash, previous history of meningitis, and a chest X-ray with patchy opacifications with new oxygen requirements prompted empirical antibiotics and steroids to cover for a chest and possible central nervous system (CNS) infection. Despite antibiotics, inflammatory markers kept rising, necessitating a switch to broad-spectrum antibiotics with subsequent clinical improvement. Later, a positive anti-proteinase 3 antibody test and a CT chest scan showing bilateral ground glass opacities confirmed granulomatosis with polyangiitis (GPA). Management included a weaning course of steroids, proton pump inhibitors, and rituximab infusions. This case highlights the need to consider autoimmune conditions like GPA in autistic patients with multi-system involvement.