Medical lung diseases

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The medical lung diseases are a huge topic. Most pathologists have little to do with 'em. They are the domain of respirology. An introduction to lung pathology is in the lung article, along with a general approach. Interstitial lung disease is dealt with in the diffuse lung diseases article.

Infectious pneumonia




Chronic obstructive pulmonary disease, abbreviated COPD, is dealt with in the emphysema article.

Chronic bronchitis


  • Often seen together with emphysema with which it is lumped together with in the term COPD.
  • It's a clinical diagnosis - criteria:[1]
    • Cough with sputum for thee months in at least two consecutive years.
    • No other cause identified.




  • Mucous gland hypertrophy + mucinous secretions in airway.
  • Goblet cell metaplasia.
  • Bronchiolar inflammation and fibrosis.

Pulmonary edema



Features - autopsy:

  • Bubbles - when squeezed (due to surfactant).
  • Heavy.



  • Dilated capillaries.
  • Blood in airspace, focal.
  • Plasma proteins in airspace - light pink acellular junk.
  • +/-Hemosiderin-laden macrophages (known as heart failure cells in this context).




Pulmonary hemorrhage

Constrictive bronchiolitis

  • AKA bronchiolitis obliterans, AKA obliterative broncholitis,[3] AKA bronchiolitis obliterans syndrome (BOS).[4]

Diffuse lung diseases

These are also known as idiopathic interstitial pneumonias.


Histomorphological classification

  1. Hyaline membranes - glassy pink material lining airways & alveoli.
  2. Microscopic honeycombing - "holes" in the lung.
  3. Bronchiolization - ciliated (respiratory) epithelium in distal airway.
  4. Uniform alveolar septal thickening - septae look similar at low power.
  5. Peripheral lobular fibrosis - septae thickening peripheral, HRCT shows: irregular peripheral reticular opacities.[5]
    • Reticular = net-like.[6]
  6. Siderophages in alveoli - macrophages with hemosiderin the alveoli.
  7. Fibrinous pleuritis - peripheral only (based on imaging).
  8. Granulomata, non-necrotizing.
  9. Abundance of vacuolated cells.
  10. Chronic inflammation.
  11. Bronchiolocentric scarring - fibrosis concentrated around airway/assoc. with airway.

Radiologic/gross pathologic DDx by location

Causes of lower lung fibrosis BAD RASH:[7]


Causes of upper lung fibrosis FASSTEN:[7]


  • The pattern and severity of fibrosis seems to be the most important factors prognostically - more important than the underlying cause (ILD, CVD, drug reaction etc.).[9][10]

Patterns of fibrosis:

  • "Linear" - follows alveolar walls, no architectural distortion.
  • UIP-like (honeycombing).

Disease with fibrosis

There are many of 'em.

Fibrosing pleuritis

Lymphocytic lesions of the lung

Diagnosis Key histologic feature Radiology Other diagnostic
Lymphocytic interstitial pneumonia interstitial lymphoid cells, usu. no nodules interstitial pattern
Follicular bronchiolitis/bronchitis lymphoid cell around bronchioles / bronchus, normal parenchyma interstitial pattern
Nodular lymphoid hyperplasia abundant lymphoid cells in nodules nodules /interstitial pattern stains to exclude lymphoma; germinal centres do not exclude lymphoma
Lymphoma (BALToma) abundant lymphoid cells usu. in nodules nodules / interstitial pattern may require stains to prove, germinal centres may be present

Lymphocytic interstitial pneumonia

Follicular bronchitis/bronchiolitis

Pulmonary nodular lymphoid hyperplasia

Lymphoma of the lung

Smoking associated disease

All of the above are associated with smoking. RBILD & DIP are considered by many to be on a continuum, i.e. RBILD is early DIP.

Respiratory bronchiolitis

  • Diagnosis is based on clinical criteria.



  • Inflammation.
  • No interstitial lung disease, i.e. no fibrosis.

Respiratory bronchiolitis interstitial lung disease

Desquamative interstitial pneumonia

Pulmonary Langerhans cell histiocytosis

  • AKA eosinophilic granuloma of the lung.

Granulomatous lung disease

See: Granulomas for an introduction to the general topic.

Most common:

  • Infectious - mycobacterial and fungal.[11]

Noninfectious causes:[11]



  • Diagnosis of exclusion - infection must be excluded.
  • Radiologic differential diagnosis includes carcinomatosis.[12]



  • Granulomata, well-formed, non-necrotizing.
    • Negative for microorganisms with special stains (PAS-D, GMS, AFB).
    • Granulomata - interstitial location.


Pulmonary talcosis




  • Granulomas with foreign material.
    • Foreign material often polarizes.



Miscellaneous diseases



  • AKA benign sclerosing pneumocytoma.[15]
  • Previously known as sclerosing hemangioma.


  • Abbreviated LAM.
  • AKA lymphangiomyomatosis.

Pulmonary alveolar proteinosis

  • Abbreviated PAP.

Diffuse panbronchiolitis

  • Abbreviated DPB.

Pulmonary amyloidosis




  • Interstitial cotton candy-like material - see amyloidosis.



Drug reactions

  • Effects are often non-specific.


Pulmonary hypertension

General classification:

  • Primary, i.e. primary pulmonary hypertension, or
  • Secondary, e.g. due to congenital heart disease (like ventricular septal defect), interstitial pulmonary fibrosis.

Non-secondary pulmonary hypertension



Eosinophilic pneumonia

Specific entities:[18]

Entities which may have eosinophilia as prominent feature:

Churg-Strauss syndrome



Eosinophilic pleural effusions

  • Definition: 10%+ eosinophils.[19]
  • Uncommon 5-16% of effusions.[20]

Causes - mnemonic I'M PAID:[20]

  • Infection, e.g. tuberculosis.
  • Malignancy - uncommon.
  • Pulmonary emboli.
  • Asbestos exposure.
  • Inflammatory diseases.
  • Drug reactions.

Lung transplant pathology

This subspecialty is dealt with in its own article.

See also


  1. 1.0 1.1 1.2 Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 370. ISBN 978-1416054542.
  2. Klatt, Edward C. (2006). Robbins and Cotran Atlas of Pathology (1st ed.). Saunders. pp. 102. ISBN 978-1416002741.
  3. Cite error: Invalid <ref> tag; no text was provided for refs named pmid16493150
  4. Sato, M.; Keshavjee, S. (2008). "Bronchiolitis obliterans syndrome: alloimmune-dependent and -independent injury with aberrant tissue remodeling.". Semin Thorac Cardiovasc Surg 20 (2): 173-82. doi:10.1053/j.semtcvs.2008.05.002. PMID 18707652.
  7. 7.0 7.1 Yeung, J.C.; Leonard, Blair J. N. (2005). The Toronto Notes 2005 - Review for the MCCQE and Comprehensive Medical Reference (2005 ed.). The Toronto Notes Inc. for Medical Students Inc.. pp. R13. ISBN 978-0968592854.
  8. Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 90. ISBN 978-0781765275.
  9. Bjoraker JA, Ryu JH, Edwin MK, et al. (January 1998). "Prognostic significance of histopathologic subsets in idiopathic pulmonary fibrosis". Am. J. Respir. Crit. Care Med. 157 (1): 199-203. PMID 9445300.
  10. AC UBC S.425.
  11. 11.0 11.1 Mukhopadhyay S, Gal AA (May 2010). "Granulomatous lung disease: an approach to the differential diagnosis". Arch. Pathol. Lab. Med. 134 (5): 667–90. PMID 20441499.
  12. URL: Accessed on: 23 May 2010.
  13. Davis, LL. (Dec 1983). "Pulmonary "mainline" granulomatosis: talcosis secondary to intravenous heroin abuse with characteristic x-ray findings of asbestosis.". J Natl Med Assoc 75 (12): 1225–8. PMC 2561715. PMID 6655726.
  14. Marchiori, E.; Lourenço, S.; Gasparetto, TD.; Zanetti, G.; Mano, CM.; Nobre, LF. (Apr 2010). "Pulmonary talcosis: imaging findings.". Lung 188 (2): 165-71. doi:10.1007/s00408-010-9230-y. PMID 20155272.
  15. Chan, KW.; Gibbs, AR.; Lo, WS.; Newman, GR. (Jun 1982). "Benign sclerosing pneumocytoma of lung (sclerosing haemangioma).". Thorax 37 (6): 404-12. PMID 6291188.
  16. Hagmeyer, L.; Stieglitz, S.; Röcken, C.; Randerath, W. (Jun 2012). "[Amyloidosis in Pneumology.]". Pneumologie. doi:10.1055/s-0032-1309811. PMID 22692971.
  17. Bush A (December 2000). "Pulmonary hypertensive diseases". Paediatr Respir Rev 1 (4): 361-7. doi:10.1053/prrv.2000.0077. PMID 16263465.
  19. Matthai, SM.; Kini, U. (Feb 2003). "Diagnostic value of eosinophils in pleural effusion: a prospective study of 26 cases.". Diagn Cytopathol 28 (2): 96-9. doi:10.1002/dc.10227. PMID 12561030.
  20. 20.0 20.1 Kalomenidis, I.; Light, RW. (Jul 2004). "Pathogenesis of the eosinophilic pleural effusions.". Curr Opin Pulm Med 10 (4): 289-93. PMID 15220754.

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