Fig.13.27 ).Thecharacteristiclinear pattern of immunoglobulin deposition (usuallyIgG,sometimesIgAorIgM)thatisthehallmarkdiagnosticfindinginrenalbiopsyspecimens(Chapter14)alsomaybeseenalongthealveolarsepta.
Most cases of Goodpasture syndrome occur in patients in their teens or twenties. In contrast to many other autoimmune diseases, there is a male preponderance. The majority of patients are active smokers. Plasmapheresis and immunosuppressive therapy have markedly improved a once-dismal prognosis. Plasma exchange removes offending antibodies, and immunosuppressive drugs inhibit antibody production. With severe renal disease, renal transplantation is eventually required.
More than 80% of patients with granulomatosis and polyangiitis (GPA; formerly Wegener granulomatosis) develop upper-respiratory or pulmonary manifestations at some time in their course. This is discussed in Chapter 10. Here we list the salient pulmonary features. The lung lesions are characterized by a combination of necrotizing vasculitis (“angiitis”) and parenchymal necrotizing granulomatous inflammation. The signs and symptoms stem from involvement of the upper-respiratory tract (chronic sinusitis, epistaxis, nasal perforation) and the lungs (cough, hemoptysis, chest pain). Anti-neutrophil cytoplasmic antibodies (PR3ANCAs) are present in close to 95% of cases (Chapter 10).
Pulmonary infections in the form of pneumonia are responsible for one sixth of all deaths in the United States. Pneumonia can be broadly defined as any infection in the lung. Normally, the lung parenchyma remains sterile because of a number of highly effective immune and non-immune defense mechanisms that extend throughout the respiratory system from the nasopharynx to the alveolar air spaces (
Fig. 13.28 ). The vulnerability of the lung to infection dsepite these defenses is not surprising because (1) many microbes are airborne and readily inhaled into the lungs; (2) nasopharyngeal flora are regularly aspirated during sleep, even by healthy individuals; and (3) lung diseases often lower local immune defenses.
The importance of immune defenses in preventing pulmonary infections is emphasized by patients with inherited or acquired defects in innate immunity (including neutrophil and complement defects) or adaptive immunity (e.g., humoral immunodeficiency), all of which lead to an
Fig. 13.27 Diffusealveolarhemorrhagesyndrome.(A)Lungbiopsyspecimendemonstrateslargenumbersofintraalveolarhemosiderin-ladenmacrophagesonabackgroundofthickenedfibroussepta.(B)ThetissuehasbeenstainedwithPrussianblue,anironstainthathighlightstheabundantintracellularhemosiderin.(From the Teaching Collection of the Department of Pathology,Children’s Medical Center,Dallas,Texas.) http://ebooksmedicine.net