A Distinctive Case of Acute Alveolar Hyaline Membrane Formation In Microscopic Polyangiitis.

Microscopic Poly Angiitis (MPA) is a systemic necrotizing vasculitis that affects small vessels and is without granulomatous formation. The kidneys and lungs are the most frequently affected organs. The pulmonary manifestations of microscopic polyangiitis are diverse and range from antecedent interstitial fibrosis to alveolar hemorrhage secondary to diffuse alveolar damage and pulmonary capillaritis. Awareness of this condition and a prompt diagnosis is warranted as this is severe and life threatening condition. The need to distinguish true primary systemic vasculitis from its multiple potential mimickers is one of the most challenging diagnostic puzzles in clinical medicine. We are presenting a case with finding of acute alveolar hyaline membrane formation on open lung biopsy in a patient fulfilling criteria of MPA. Once diagnosed, this life threatening condition has to be treated with systemic steroids, Rituximab or Cyclophosphamide induction therapy, as well as plasmapheresis in some cases. Keywords: Microscopic polyangiitis; Alveolar hyaline membrane formation