A 76 year-old man presents with a florid spreading violaceous rash over most of his body - Palpable Purpura - What is your differential diagnosis?
Polyangiitis - MPA, GPA, EGPA: similar but different diseases; positive Antineutrophil cytopasmic antibiodies (ANCA); renal histology (focal necrotizing, pauci-immune glomerulonephritis)
The eponym 'Wegener Granulomatosis' has been replaced with the term 'Granulomatosis with polyangiitis (GPA)'. This transition was in part to achieve nomenclature symmetry with Microscopic Polyangiitis (MPA) and Eosinophilic granulomatosis with polyangiitis (EGPA, Churg-Strauss); and to remove any historical association with Friedrich Wegener following revelations of his association with the Nazi Party in World War II
Friedrich Wegener (1907-1990) was a German pathologist. Affiliated with Wegener granulomatosis, now termed granulomatosis with polyangiitis (GPA)