Usual Interstitial Pneumonia (UIP) is a specific term used by lung pathologists as one of several interstitial pneumonias (the interstitium is a word used for the cellular support structures of the lung). UIP is the most common type of interstitial pneumonia.

IPF is often used as synonymous with UIP because UIP is the most common cellular pattern, and its cause is usually not known. The designation “IPF/UIP” is also commonly used to describe this process of progressive pulmonary fibrosis.

UIP appears as a patchy and temporally variegated (both early and late components) fibrosis with little inflammation  The fibroblastic focus (an area of proliferating fibroblasts located at the leading edge of new fibrosis) is the hallmark of the disease   When UIP occurs in the absence of a known cause, the clinical diagnosis is IPF, while in the setting of other diseases, such as collagen vascular disease, it is termed secondary UIP. Secondary UIP may behave differently and will not be further discussed.

The term “cryptogenic fibrosing alveolitis” is synonymous with UIP

Idiopathic pulmonary fibrosis usually occurs in patients who are beyond 50 years of age.

Past tobacco use greatly increases the risk of IPF

 

UIP show three findings in the lung tissue:

(1) Areas of normal lung,

(2) Areas of inflammation, and

(3) Areas of end-stage, scared, and non-functioning cystic lung with the appearance of a honeycomb. “Architectural derangement” of the lung is seen. “Fibroblastic foci” seen in the areas of inflamed lung establish the diagnosis of UIP. These foci are scar-forming cells called fibroblasts. These cells are rarely seen in
healthy lungs, and their presence in a group (foci) indicates the ongoing scarring process of UIP. Sometimes the area of inflammation has the appearance of cellular organization called BOOP

 

Differential Diagnoses Related to IPF

• Systemic/rheumatic abnormalities
  • Progressive systemic sclerosis (PSS)
  • Systemic lupus erythematosus (SLE)
  • Sjögren’s syndrome (SS)
  • Ankylosing spondylitis (AS)
  • Rheumatoid arthritis (RA)
  • Mixed connective tissue disease (MCTD)
  • Polydermatomyositis
  • Chronic aspiration pneumonia
• Drug/radiation-induced
  • Antibiotics
  • Cardiovascular drugs
  • Chemotherapeutic agents
  • Radiation
• Malignancies
  • Lymphoma
  • Lymphangitic carcinoma
• Sarcoidosis
• Idiopathic interstitial pneumonias (IIPs)
  • Idiopathic pulmonary fibrosis (IPF)
  • Nonspecific interstitial pneumonia (NSIP)
  • Desquamative interstitial pneumonia (DIP)
  • Respiratory bronchiolitis-associated interstitial lung disease (RBILD)
  • Acute interstitial pneumonia (AIP)
• Occupational injuries
  • Inorganic fibrogenic disorders
  • Inorganic nonfibrogenic disorders
• Bronchiolitis obliterans organizing pneumonia (BOOP)
• Lymphangioleiomyomatosis (LAM)
• Eosinophilic granuloma (EG)
• Hypersensitivity pneumonitis
  • Organic dust
  • Bacteria
  • Animal protein
  • Fungi
• Lymphocytic interstitial pneumonitis (LIP)
  • Sjögren’s syndrome (SS)
  • Lymphoma (low-grade)
  • HIV infection
• Giant cell interstitial pneumonitis (GIP)
  • Hard metal pneumoconiosis
• Imaging
• MDCT
  • reduce lung volumes,
  • predominantly in basilar areas
  • subpleural fibrosis ,
  • traction bronchiectasis

Links and References

• Videos 
  • AUR
    

    Title	web link
    Current Guidelines in the Dx of UIP and IPF	AUR Cardiothoracic Imaging

  • Title	web link
    Early ILD What Next	AUR Cardiothoracic Imaging

• Journals

1. 1. 1. American Thoracic Society. Idiopathic pulmonary fibrosis: diagnosis and treatment (international consensus statement). Am J Respir Crit Care Med. 2000;161:646-664.
      2. Bjoraker JA, Ryu JH, Edwin MK, et al. Prognostic significance of histopathologic subsets in idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 1998;157:199-203.
      3. Gay SE, Kazerooni EA, Toews GB, et al. Idiopathic pulmonary fibrosis: predicting response to therapy and survival. Am J Respir Crit Care Med. 1998;157:1063-1072.
      4. Hubbard R, Johnston I, Britton J. Survival in patients with cryptogenic fibrosing alveolitis: a population-based cohort study. Chest. 1998;113:396-400.
      5. Johnston ID, Prescott RJ, Chalmers JC, Rudd RM, for the Fibrosing Alveolitis Subcommittee of the Research Committee of the British Thoracic Society. British Thoracic Society study of cryptogenic fibrosing alveolitis: current presentation and initial management. Thorax. 1997;52:38-44.
      6. Mapel DW, Hunt WC, Utton R, Baumgartner KB, Samet JM, Coultas DB. Idiopathic pulmonary fibrosis: survival in population based and hospital based cohorts. Thorax. 1998;53:469-476.
      7. Strieter RM, Keane MP. Cytokine biology and the pathogenesis of interstitial lung disease. In: King TE Jr, ed. New Approaches to Managing Idiopathic Pulmonary Fibrosis. New York, NY: American Thoracic Society; 2000:27-35.
      8. Selman M, King TE Jr, Pardo A. Idiopathic pulmonary fibrosis: prevailing and evolving hypotheses about its pathogenesis and implications for therapy. Ann Intern Med. 2001;134:136-151.
      9. Leslie KO. The pathology of idiopathic pulmonary fibrosis. In: King TE Jr, ed. New Approaches to Managing Idiopathic Pulmonary Fibrosis. New York, NY: American Thoracic Society; 2000:8-13.
      10. Katzenstein ALA, Myers JL. Idiopathic pulmonary fibrosis: clinical relevance of pathologic classification. Am J Respir Crit Care Med. 1998;157:1301-1315.
      11. American Thoracic Society. International guidelines for the selection of lung transplant candidates. Am J Respir Crit Care Med. 1998;158:335-339.
      12. Mason RJ, Schwarz MI, Hunninghake GW, Musson RA. Pharmacological therapy for idiopathic pulmonary fibrosis: past, present, and future. Am J Respir Crit Care Med. 1999;160:1771-1777.
      13. du Bois RM. Potential future approaches to the treatment of idiopathic pulmonary fibrosis. In: King TE Jr, ed. New Approaches to Managing Idiopathic Pulmonary Fibrosis . New York, NY: American Thoracic Society; 2000:52-57.

TCV

1. 1. Idiopathic Pulmonary Fibrosis
   2. Imaging
   3. Interstitial Lung Disease and Emphysema
   4. Interstitial Lung Disease ILD and Scleroderma
   5. Interstitial Lung Disease, ILD and Connective Tissue Disease
   6. Interstitial Lung Disease, ILD and Pulmonary Hypertension, PHA
   7. Interstitial Lung Disease, ILD, and Rheumatoid Arthritis , RA
   8. Interstitial Lung Disease, ILD, Usual Interstitial Lung Disease, UIP
   9. Interstitial Lung Disease, IPF, and Hiatus hernia
   10. Interstitial Lung Diseases
   11. Interstitial Pneumonias, ILD