Smoking associated lung diseases

  1. Pulmonary Langherhans cell histiocytosis:
  • Clinical features:
    • Young adult smokers around 20-40 years
    • Involves single site or may be multicentric involving other organs at the same time or progressively
    • Lung involvement is in more than 50%
    • Bone, skin, lymph nodes, pituitary gland and other areas are also involves
  • Etiology:
    • Unknown but association with smoking is significant
    • Patients get better after smoking cessation
  • Imaging studies:
    • Cystic and nodular abnormalities in upper and middle lung more pronounced in peripheral lung fields
  • Histologically:
    • Interstitial lesion with stellate or starfish shaped appearance
    • Tissue is infiltrated by sheets of langerhans cells
    • Langerhans cells have glassy-pink cytoplasm with indistinct cell borders
    • Syncytial appearance
    • Nuclei show longitudinal grooves and undulating nuclear membrane
    • Langerhans cells are more prominent in the central area and the peripheral area shows inflammatory infiltrate with numerous eosinophils
    • Obliterated small arteries and veins are common
  • Immunohistochemical staining:
    • S100 nuclear and cytoplasmic positivity
    • Langerin and CD1a positive
  • Ultrastructural findings
    • Birbeck granules
  1. Emphysema: It is irreversible dilation of air spaces distal to terminal bronchioles with destruction of alveolar walls without obvious fibrosis and lack of elastosic recoil
  • Clinical findings:
    • Dyspnea , slow in onset but progressive
    • Cough, expectoration and wheeze are variable
    • Hypoxia, cyanosis and respiratory acidosis (pink puffers)
    • Barrel shaped chest, pursed lips and hunched over position
    • Pulmonary function test show impaired expiratory airflow and increased total vital capacity
  • Types of Emphysema:
    • Centiacinar (centrilobular) emphysema:
      • Proximal or central part of acini formed by respiratory bronchioles are affected and the distal alveoli are spared
      • Associated with smoking
    • Panacinar (panlobular) Emphysema:
      • Acini are uniformly enlarged from respiratory bronchioles to terminal alveoli
      • It is associated with alpha1- antitrypsin deficiency
      • More common in lowr zones and anterior margins of lung
    • Distal acinar (paraseptal) emphysema:
      • The distal part of acinus is associated and the proximal part is normal
      • More striking adjacent to pleura
      • Sometimes associated with large subpleural blebs and cystlike structures
    • Irregular emphysema:
      • Irregular involvement of acinus
      • Associated with fibrosis and scarring
      • Usually a complication of an inflammatory process
    • Microscopic features:
      • Abnormally large alveoli
      • Separated with thin alveolar septa with only focal centrilobular fibrosis
    • Pathogenesis:                                                                                                   Factors that influence the development of emphysema are:
      • Inflammatory mediaters:
        • LTB4, IL-8, TNF and others
      • Protease-antiprotease imbalance:
      • Oxidative stress
      • Infection
    • Treatment options:
      • Smoking cessation
      • Oxygen therapy
      • Long-acting bronchodilators with inhaled corticosteroids
      • Physical therapy
      • bullectomy
      • lung volume reduction therapy and transplantation in selected patients
      • alpha1-antitrypsin replacement is under consideration
    • Complications:  
    • death in most patients is due to
      • Coronary artery disease
      • Respiratory failure
      • Right-sided heart failure
      • Massive collapse of lungs

 

  1. Chronic Bronchitis:
  • It is defined as persistent productive cough for at last 3 consecutive months in at least 2 consecutive years
  • Cigarette smoking is important association with contribution of air pollutants as well
  • Clinical features:
    • Persistent cough with sparse sputum
    • Eventual dyspnea on exertion
    • Hypercapnia, hypoxemia and mild cyanosis (blue-bloaters)
  • Histological Features:
    • Enlargement of mucus-secreting glands
    • Goblet cell hyperplasia
    • Bronchiolar wall fibrosis
    • Chronic inflammatory infiltrate
  • Pathogenesis:
    • Smoke, tobacco and dust are initiating factors
    • Mucus hypersecretion: due to hyperytrophy of mucus secreting glands and goblet cell hyperplasia
    • Inflammation: acute and chronic causing cellular damage
    • Infection: does not initiate it but has a role in acute exacerbations

 

 

 

 

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