The Lung part 7 Flashcards
Diffuse pulmonary hemorrhage syndromes
- complication of interstitial lung disorders; include:
- Goodpasture’s syndrome
- Idioathic pulmonary hemosiderosis
- vasculitis associated hemorrhage found in conditions like hypersensitivity angiitis, Wegner’s granulomatosis, and SLE
Goodpasture’s syndrome
- uncommon autoimmune dz
- kidney and lung injury caused by circulating autoAb against non-collagenous domain of a3 chain of collagen IV
- if only kidney involved, called glomerular BM dz
- Abs initiate inflammatory destruction of BM in renal glomeruli and pulmonary alveoli leading to RPGN and a necrotizing hemorrhagic interstitial pneumonitis
- teens or 20s (but any age can be affected), males
- majority of patients are smokers!
Pathogenesis of Goodpasture’s syndrome
- trigger for anti-BM Abs unknown
- env insult like viral infxn, exposure to hydrocarbon solvents (drycleaning), or smoking thought to be required to unmask cryptic epitopes
- genetic predisposition–associated with HLA-DRB1*1501 and *1502
Goodpasture’s syndrome morphology
- heavy lungs w/areas of red-brown consolidation
- Histo: focal necrosis of alveolar walls associated with intra-alveolar hemorrhages
- alveoli contain hemosiderin-laden macrophages
- later stages: fibrous thickening of septae, hypertrophy of type II pneumocytes, organization of blood in alveolar spaces
- IF: LINEAR deposits of Ig along BM of septal walls
- kidneys=focal prolif GN in early cases or crescentic GN in pts with RPGN
Diagnostic morphology for Goodpastures
-Linear deposits of Igs and complement by IF along glomerular BM even in the patients w/o renal disease
Clinical features of Goodpastures
- begin w/resp symptoms–hemoptysis
- radiography: focal pulmonary consolidations
- Soon see GN–> to rapidly progressive renal failure
Most common cause of death in Goodpasture’s syndrome
-UREMIA!
Prognosis and treatment for Goodpasture’s
- before prognosis was dismal but now much better due to PLASMAPHERESIS–removes circulating anti-BM Abs and chemical mediators of immunologic injury
- simultaneous immunosuppressive tx inhibits further Ab production, relieving both lung hemorrhage and GN
Idiopathic pulmonary hemosiderosis
- rare
- intermittent, diffuse alveolar hemorrhage
- mostly young children! but can see in adults
- gradual onset of productive cough, hemoptysis, anemia associated with diffuse pulmonary infiltrations similar to Goodpasture’s
Cause and pathogenesis of idiopathic pulmonary hemosiderosis
- unknown!
- No anti-BM Abs detectable
- favorable response to long term immunosuppression w/prednisone/ azathioprine indicates immunologic mechanism involved in pulm capillary damage/bleeding
- some pts develop other immune disorders
Polyangiitis with granulomatosis
- Wegner’s granulomatosis
- involves upper respiratory tract and/or lungs
- hemoptysis is common presenting symptom
- transbronchial biopsy=only tissue available for Dx; since amt of tissue is small, necrosis and granulomatous vasculitis may not be present
- Diagnostically important are capillaritis and scattered, poorly formed granulomas (unlike those of sarcoidosis which are rounded and well-defined!)
Majority of resp tract infections are
- Upper respiratory tract infections (cold, pharyngitis)
- Bacterial, viral, mycoplasmal and fungal infections of lung (pneumonia) still pretty common
Pneumonia results whenever
- local degense mechanisms are impaired or systemic resitance of host is lowered by things like:
- chronic disease, immunologic deficiency, treatment with immunosuppressive agents, leukopenia
Examples of how local defense mechanisms of the lung are compromised (5)
- Loss or suppression of cough reflex
- Injury to mucociliary apparatus
- Accumulation of secretions
- Interference with the phagocytic or bactericidal action of alveolar macrophages
- Pulmonary congestion and edema
Loss or suppression of cough reflex caused by
-from coma, anesthesia, neuromuscular disorders, drugs, or chest pain (may lead to aspiration of gastric contents)
Injury to mucociliary apparatus by
-by either impairment of ciliary function or destruction of ciliated epithelium due to cigarette smoke, inhalation of hot or corrosive gases, viral diseases, or genetic defects of ciliary function (immotile cilia syndrome)
Accumulation of secretions–seen in conditions like
cystic fibrosis and bronchial obstruction
Interference with the phagocytic or bactericidal action of alveolar macrophages by what substances?
-alcohol, tobacco smoke, anoxia or oxygen intoxication
Defects in innate immunity (neutrophil and complement) and humoral immunodeficiency typically leads to increased incidence of infections with
-pyogenic bacteria
Germline mutations in ___is associated with dustructive bacterial (pneumococcal) pneumonias
-MYD88–adaptor for many TLRs that is important for activation of transcription factor NFkb
Cell-mediated immune defects (congenital and acquired) lead to
-increased infections with intracellular microbes like mycobacteria and herpesviruses as well as with microorganisms of very low virulence like Pneumocystis jiroveci