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.

This article includes a discussion about pulmonary hypertension, which may arise due to congenital heart disease.

Acute infectious pneumonia

This is seen by pathologists in autopsy from time-to-time.

Radiologic correlate

  • Air space disease.

Gross pathology

  • Consolidation (the lung parenchyma is firm) - best appreciated by running a finger over the cut surface from normal region to abnormal region.

Microscopy

Features:

  • Alveoli packed with PMNs.
  • +/-Clusters of bacteria - small dots or rods.

Image: Normal alveoli & pneumonia (WC).

Asthma

General

  • The bread and butter of respirology.
  • Associated with atopy.
  • Mast cells thought to play an important role.

Microscopic

Features:[1]

  • Edema.
  • Mucous.
  • +/-Smooth muscle hypertrophy.
  • +/-Inflammation - especially with eosinophils.
  • +/-Charcot-Leyden crystals (formed from eosinophilic granules).
    • Sharp edge, diamond shaped, intense pink.

Images:

Notes:

  • Leyden in Charcot-Leyden is also seen written as Leiden.

Idiopathic interstitial pneumonia

  • Often abbreviated IIP, is a term used for a type of diffuse lung disease.
    • Diffuse lung disease is also known as interstitial lung disease.
      • Diffuse lung disease is probably a better term... as some diseases lumped into this category have involvement of the alveoli, i.e. are not interstitial.

Histologic classification of IIP

Idiopathic interstitial pneumonia can be subclassified based on histologic appearance into the following patterns:[5][6]

Histology Clinical Correlates
Desquamative interstitial pneumonia (DIP) DIP
Diffuse alveolar damage (DAD) ARDS, AIP, TRALI
Nonspecific interstitial pneumonia (NSIP) NSIP
Respiratory bronchiolitis RB-ILD
Usual interstitial pneumonia (UIP) CVD, IPF, drug toxicity, pneumoconiosis
Organizing pneumonia Cryptogenic organizing pneumonia
Lymphoid interstitial pneumonia (LIP) LIP

ARDS = adult respiratory distress syndrome, AIP = acute interstitial pneumonia, TRALI = transfusion related acute lung injury, CVD = collagen vascular disease, IPF = idiopathic pulmonary fibrosis.


Notes:

  • Usual interstitial pneumonia is the most common type of ILD.[7]

Fibrosis

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.[8]
    • Reticular = net-like.[9]
  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:[10]

  • Brochiolitis obliterans with organizing pneumonia (BOOP),
  • Asbestosis,
  • Drugs (nitrofurantoin, hydralazine, isoniazid (INH), amiodarone),
  • Rheumatologic disease,
  • Aspiration,
  • Scleroderma,
  • Hamman-Rich syndrome (really should be -- interstital pulmonary fibrosis).

Causes of upper lung fibrosis FASSTEN:[11]

  • Farmer's lung,
  • Ankylosing spondylitis,
  • Sarcoidosis,
  • Silicosis,
  • Tuberculosis (miliary),
  • Eosinophilic granuloma,
  • Neurofibromatosis.

Prognosis

  • 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.).[12][13]

Patterns of fibrosis:

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

Disease with fibrosis

There are many of 'em.

Diffuse alveolar damage

General

  • Abbreviated DAD.

DAD is the histologic correlate of:

  • Adult respiratory distress syndrome (ARDS).
  • Acute interstitial pneumonia (AIP).
  • Transfusion related acute lung injury (TRALI).

Microscopic

Features:[14]

  • Early:
    • Hyaline membrane: debris (pink crap) lines the alveolar spaces.
  • Intermediate:
    • Macrophage proliferation.
  • Late:
    • Interstitial inflammation.
    • Fibrosis.

Image: Diffuse alveolar damage (WC).

Usual interstitial pneumonia

General

  • It is sometimes used incorrectly as a synoym for idiopathic pulmonary fibrosis.
  • Cannot be diagnosed via bronchoscopic or transbronchial biopsy.[15]

Epidemiology

  • Disease of the old - rare in under 50 years old.[16]
  • Dismal prognosis - mean survival after diagnosis ~ 2.8 years.[12]

Differential diagnosis

UIP is seen in:[17]

  • Idiopathic pulmonary fibrosis,
  • Asbestosis,
  • Chronic hypersensitivity pneumonitis (extrinsic allergic alveolitis),
  • Collagen vascular disease and
  • chronic drug toxicity.[18]

Radiologic

  • Honeycombing - multiple defects that obliterate the normal lung architecture - multiple spherical voids in the lung parenchyma; radiologically these are seen as lucencies.[19]
    • Usually subplural, i.e. peripheral lung.
    • Classically lower lobe predominant.
    • Assoc. with interstitial thickening ???

Note:

  • Cysts - have thin walls (think of emphysema, lymphangioleiomyomatosis et cetera).
    • Cysts may be isolated/not close to a neighbour.
    • Medcyclopaedia defines it as: thin-walled, well-demarcated and >1 cm.[20]

Histology

Features:[21]

  • Fibroblast foci:
    • "Crescent-shaped bulge" of fibroblasts -- a rounded projection of spindle cells into the airspace.
    • Location: in the areas of transisition between active inflammation and old inflammation.[22]
    • Note: Technically, fibroblast foci are composed of myofibroblasts.[23]
  • Interstitial inflammation,
  • Microscopic honeycombing,
    • Typically peripheral - cysts lined by ciliated epithelium.
  • Spatial heterogeneity - patchy lesional distribution (areas of abnormal and normal lung may appear beside one another).
  • Temporal heterogeneity - lesions of differing age side-by-side.[24]

Notes:

  • Disease worse distant from large airways: lower lung field predominance, typically worse at periphery of lobule and lung.[25]
  • Heterogeneity of inflammation: airspace macrophages & inflammation minimal in honeycombed foci.

Non-specific interstitial pneumonia

  • Abbreviated NSIP.
  • Better prognosis than UIP.
  • Some radiologists and pathologists don't believe in this entity.

Gross/Radiology

  • No honeycombing.
  • Fibrosis usually lower lung zone.
  • Patchy ground glass.

Microscopic

  • Fibrosis:
    • May be uniform.
    • "Linear fibrosis" has a good prognosis - should be mentioned in the report.
      • Linear fibrosis = fibrosis that follows alveolar walls + no architectural distortion.
  • +/-Lymphoid nodules - assoc. with collagen vascular disease.

Notes:

  • Like UIP... also temporally and spatially heterogeneous.
  • Inflammation in NSIP usually more prominent than in UIP.
  • No honeycombing - key difference between UIP and NSIP.

DDx

  • Collagen vascular disease.
  • Drug reaction.
  • Hypersensitivity pneumonitis (extrinic allergic alveolitis).

Diseases with prominent bronchiolization

There are many.

Pulmonary Langerhans cell histiocytosis

General

  • Assoc. with smoking.[26]
  • Not assoc. with systemic diseases of Langerhans cells (AKA Hand-Schueller-Christian disease).

Subtypes:[26]

  • Cellular form.
  • Fibrotic form.

One form usually predominantes.

Histology

Features:[27]

  • Langerhans cells:
    • Pale staining nucleus (H&E) with nuclear infolding - "crumpled tissue paper" appearance.
  • +/-Smoker's macrophages.
  • +/-Eosinophilia.

IHC

  • Langerhans cells: S100+ and CD1a+.[28]

Smoking assoc. disease

  • RB = respiratory bronchiolitis.
  • RBILD = respiratory bronchiolitis interstitial lung disease.
  • DIP = desquamative interstitial pneumonia.
  • Eosinophilic granuloma (of lung) - AKA pulmonary langerhans cell histiocytosis.

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

Respiratory bronchiolitis

  • No interstitial lung disease.

RBILD

General

  • Respiratory bronchiolitis interstitial lung disease.

Histology

Features:[29]

  • Brown pigmented airspace macrophages - smoker's macrophages.
  • Inflammation of the terminal bronchioles.

Note:

  • The histologic features of RBILD may be present peri-tumoural.

DIP

  • Desquamative interstitial pneumonia.
  • Thought to be advanced RBILD.

Histology

  • Brown pigmented airspace macrophages - smoker's macrophages.
  • Architecture preserved; "linear fibrosis".

Notes:

  • Some fields of view may be indistinguishable from RBILD.
  • Amiodarone toxicity, fibrotic NSIP - may appear similar.

Eosinophilic granuloma of lung

  • Assoc. with smoking.

Radiology

  • Upper lung zones.

Histology

  • Cellular peribronchiolar nodules with:
    • Eosinophils - may be rare.
    • Langerhans cells.
    • Smoker's macrophages (brown pigmented airspace macrophages).
    • Chronic inflammatory cells (lymphocytes).

Hypersensitivity pneumonitis

  • AKA extrinsic allergic alveolitis
  • Exposure to stuffs... e.g. moldy hay - Farmer's lung, atypical mycobacteria - hot tub lung.

IHC

Nodules postive for:

  • S-100.
  • CD1a.

Miscellaneous diseases

Lymphangioleiomyomatosis

General

  • Abbreviated LAM.
  • Clinical: dyspnea, recurrent pneumothorax.
  • May be an indication for lung transplantation.

Epidemiology

Radiology

  • Bullae/thin walled cysts - distributed in all lung fields.
  • Lymphadenopathy.

Radiologic DDx (of cysts):

  • Eosinophilic granuloma (assoc. with smoking).
  • Interstitial pulmonary fibrosis (UIP).
  • Emphysema.

Histology

Features:[31]

  • Spindle cells with small nuclei + larger epithelioid cells with clear cytoplasm and round nuclei.
  • Cyst formation.
  • Thick arterial walls.

IHC:

  • HMB-45 +ve
  • ER +ve
  • PR +ve
  • SMA +ve

Pulmonary alveolar proteinosis

  • Abbreviated PAP.
  • Associated with smoking - particularily in men.[32]

Pathophysiology:

  • GM-CSF (granulocyte-macrophage colony stimulating factor) signaling in macrophages/lack of GM-CSF.
    • GM-CSF is required by alveolar macrophages to clear surfactant.

Classification:[32]

  1. Congenital:
      • Abnormal surfactant.
      • GM-CSF receptor defect.
  2. Secondary:
    • Infections.
    • Haematologic malignancy.
  3. Acquired:
    • Dusts - interfere with macrophage function.

Clinical:

  • Dyspnea & cough - gradual onset.

Radiology

Histology

  • Crap in alveoli.
  • "Dense bodies" - dead macrophages ("Chatter" in the alveoli).
    • Edema - has pink stuff in the alveoli like PAP but no dense bodies.

DDx - may mimic:

  • Edema.
  • Pneumocystis.

Drug reactions

  • Effects are often non-specific.

Website: http://www.pneumotox.com

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

Causes:[33]

  • Primary pulmonary hypertension.
  • Pulmonary embolic disease (thromboembolism, and non-thrombotic embolism).
  • Pulmonary capillary haemangiomatosis (PCH).
  • Pulmonary veno-occlusive disease (PVOD).

Notes:

  • Some people consider PCH and PVOD to the be same thing.[34]
    • Both have a poor prognosis.
    • Clinically they present the same way.
  • PVOD is based on case reports - it is extremely rare.[35]

Primary pulmonary hypertension

  • AKA pulmonary plexogenic arteriopathy.[36]
  • Like chronic pulmonary hypertension due to congenital heart disease but without the congenital heart disease.[36]
    • Classified by Heath-Edwards classification (see below) into six grades.

Pulmonary veno-occlusive disease (PVOD)

Features:[37]

  • Clinical - gradual dyspnea +/- non-productive cough, +/- clubbing.
  • Thrombosis - small veins & venules, particularily at the interlobular septae.
  • Associated with mild homogenous peripheral interstitial fibrosis.

DDx: chronic interstitial pneumonia.

Pulmonary capillary hemangiomatosis (PCH)

General:

  • First reported in 1978 by Wagenvoort et al..[38]

Features:

  • Proliferating and invasive capillaries.[39]
  • Demonstrated by CD34 immunostaining.[34]
  • Dilated capillaries[40][41] - key feature.

DDx:

  • Passive congestion (PC).
    • Differentiated by fact that PCH has multiple channels in alveolar wall (PC has only one).

Chronic pulmonary hypertension due to congenital heart disease

  • Graded using the Heath-Edwards system.[42]
  • A reason for open lung biopsy in children.[43]

Heath-Edwards classification

Definition:[42]

  • Six grades - based on intimal reaction and media of arteries and arterioles:
    • Grade 1:
      • Intima: no intimal reaction.
      • Media: hypertrophied.
    • Grade 2:
      • Intima: cellular intimal reaction.
      • Media: hypertrophied.
    • Grade 3:
      • Intima: fibrous & fibroelastic reaction + cellular intimal reaction.
      • Media: hypertrophy +/- generalized dilation.
    • Grade 4:
      • Intima: "plexiform lesions" + fibrous & fibroelastic reaction, + cellular intimal reaction.
          • Plexiform lesions = multiple channels that are dilated, assoc. with loss of elastic laminae; thought to arise at branch points due to aberant WSS.[44]
      • Media: generalized dilation +/- local "dilation lesions".
      • Micrographs: Plexiform lesions (ucsf.edu), Plexiform lesions (pvrireview.org).
    • Grade 5:
      • Intima: as in Grade 4.
      • Media: generalized dilation + local "dilation lesions" + pulmonary hemosiderosis.
    • Grade 6:
      • Intima: as in Grade 4.
      • Media: generalized dilation + local "dilation lesions" + pulmonary hemosiderosis + necrotizing arteritis.

Notes:

Eosinophilic pneumonia

Specific entities:[45]

  • Churg-Strauss syndrome.
  • Acute eosinophilic pneumonia.
  • Chronic eosinophilic pneumonia.
  • Eosinophilic granuloma (pulmonary histiocytosis X, Langerhans cell granulomatosis).

Entities which may have eosinophilia as prominent feature:

  • AIDS.
  • Lymphoma.
  • Collagen vascular disease.

Churg-Strauss syndrome

Features GAFE:

  • Granulomata.
  • Asthma.
  • Fever.
  • Eosinophilia.

General

  • AKA allergic granulomatous angiitis.[46]
  • Small vessel vasculitis.
  • Similar to Wegener's granulomatosis (classically c-ANCA +ve) and microscopic polyangiitis (a form of polyarteritis nodosa).[47]

See also

References

  1. ↑ Klatt. AOP P.108.
  2. ↑ Nicholson AG (November 2002). "Classification of idiopathic interstitial pneumonias: making sense of the alphabet soup". Histopathology 41 (5): 381-91. PMID 12405906. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0309-0167&date=2002&volume=41&issue=5&spage=381.
  3. ↑ Flaherty KR, King TE, Raghu G, et al (October 2004). "Idiopathic interstitial pneumonia: what is the effect of a multidisciplinary approach to diagnosis?". Am. J. Respir. Crit. Care Med. 170 (8): 904-10. doi:10.1164/rccm.200402-147OC. PMID 15256390. http://ajrccm.atsjournals.org/cgi/pmidlookup?view=long&pmid=15256390.
  4. ↑ Kim DS, Collard HR, King TE (June 2006). "Classification and natural history of the idiopathic interstitial pneumonias". Proc Am Thorac Soc 3 (4): 285-92. doi:10.1513/pats.200601-005TK. PMID 16738191. http://pats.atsjournals.org/cgi/pmidlookup?view=long&pmid=16738191.
  5. ↑ Leslie KO, Wick MR. Practical Pulmonary Pathology: A Diagnostic Approach. Elsevier Inc. 2005. ISBN 978-0-443-06631-3.
  6. ↑ "American Thoracic Society/European Respiratory Society International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumonias. This joint statement of the American Thoracic Society (ATS), and the European Respiratory Society (ERS) was adopted by the ATS board of directors, June 2001 and by the ERS Executive Committee, June 2001". Am. J. Respir. Crit. Care Med. 165 (2): 277-304. January 2002. PMID 11790668. http://ajrccm.atsjournals.org/cgi/pmidlookup?view=long&pmid=11790668.
  7. ↑ Visscher DW, Myers JL (June 2006). "Histologic spectrum of idiopathic interstitial pneumonias". Proc Am Thorac Soc 3 (4): 322-9. doi:10.1513/pats.200602-019TK. PMID 16738196. http://pats.atsjournals.org/cgi/pmidlookup?view=long&pmid=16738196.
  8. ↑ http://www.rsna.org/Publications/rsnanews/may06/jrnl_may06.cfm
  9. ↑ http://dictionary.reference.com/browse/reticular
  10. ↑ TN05 R13
  11. ↑ TN05 R13
  12. ↑ 12.0 12.1 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. http://ajrccm.atsjournals.org/cgi/content/full/157/1/199.
  13. ↑ AC UBC S.425.
  14. ↑ Klatt. AOP P.103.
  15. ↑ PPP P.186.
  16. ↑ AC UBC S.102.
  17. ↑ Wick, Mark R.; Leslie, Kevin (2005). Practical pulmonary pathology: a diagnostic approach. Edinburgh: Churchill Livingstone. ISBN 0-443-06631-0. OCLC 156861539.
  18. ↑ Rossi SE, Erasmus JJ, McAdams HP, Sporn TA, Goodman PC (2000). "Pulmonary drug toxicity: radiologic and pathologic manifestations". Radiographics : a review publication of the Radiological Society of North America, Inc 20 (5): 1245-59. PMID 10992015.
  19. ↑ http://www.medcyclopaedia.com/library/topics/volume_v_1/h/honeycombing.aspx
  20. ↑ http://www.medcyclopaedia.com/library/topics/volume_v_1/l/lung_cyst.aspx
  21. ↑ PPP P.186-9.
  22. ↑ http://www.epler.com/IPFWhat%27sIPFDiseaseInformation2.htm
  23. ↑ PPP P.189.
  24. ↑ H. 8 July, 2009.
  25. ↑ AC UBC S.103.
  26. ↑ 26.0 26.1 PPP P.234.
  27. ↑ PPP P.237.
  28. ↑ PPP P.237.
  29. ↑ PPP PP.197-8.
  30. ↑ 30.0 30.1 http://emedicine.medscape.com/article/299545-overview
  31. ↑ http://emedicine.medscape.com/article/299545-diagnosis
  32. ↑ 32.0 32.1 Trapnell BC, Whitsett JA, Nakata K (December 2003). "Pulmonary alveolar proteinosis". N. Engl. J. Med. 349 (26): 2527-39. doi:10.1056/NEJMra023226. PMID 14695413. http://content.nejm.org/cgi/content/extract/349/26/2527.
  33. ↑ Bush A (December 2000). "Pulmonary hypertensive diseases". Paediatr Respir Rev 1 (4): 361-7. doi:10.1053/prrv.2000.0077. PMID 16263465.
  34. ↑ 34.0 34.1 Lantuéjoul S, Sheppard MN, Corrin B, Burke MM, Nicholson AG (July 2006). "Pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis: a clinicopathologic study of 35 cases". Am. J. Surg. Pathol. 30 (7): 850-7. doi:10.1097/01.pas.0000209834.69972.e5. PMID 16819327.
  35. ↑ Vevaina JR, Mark EJ (March 1988). "Thoracic hemangiomatosis masquerading as interstitial lung disease". Chest 93 (3): 657-9. PMID 3342678.
  36. ↑ 36.0 36.1 Lie JT, Silver MD. Diagnostic criteria of cardiovascular pathology: acquired diseases. ISBN 0-397-51630-4. PP.208-9.
  37. ↑ PPP PP.393-6.
  38. ↑ Wagenvoort CA, Beetstra A, Spijker J (November 1978). "Capillary haemangiomatosis of the lungs". Histopathology 2 (6): 401-6. PMID 730121.
  39. ↑ Tron V, Magee F, Wright JL, Colby T, Churg A (November 1986). "Pulmonary capillary hemangiomatosis". Hum. Pathol. 17 (11): 1144-50. PMID 3770733.
  40. ↑ MC August 2009.
  41. ↑ PPP PP.396-7.
  42. ↑ 42.0 42.1 HEATH D, EDWARDS JE (October 1958). "The pathology of hypertensive pulmonary vascular disease; a description of six grades of structural changes in the pulmonary arteries with special reference to congenital cardiac septal defects". Circulation 18 (4 Part 1): 533-47. PMID 13573570.
  43. ↑ Jaklitsch MT, Linden BC, Braunlin EA, Bolman RM, Foker JE (June 2001). "Open-lung biopsy guides therapy in children". Ann. Thorac. Surg. 71 (6): 1779-85. PMID 11426747.
  44. ↑ http://pathhsw5m54.ucsf.edu/overview/vessels.html
  45. ↑ http://emedicine.medscape.com/article/301070-overview
  46. ↑ http://emedicine.medscape.com/article/333492-overview
  47. ↑ http://emedicine.medscape.com/article/334024-overview

External links

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