Cystic-Cavitary Lung Lesions


General Definitions

  • Cavity (Pathologic Definition): gas-filled space within a zone of pulmonary consolidation or within a mass or nodule, produced by the expulsion of a necrotic part of the lesion via the bronchial tree
  • Cavity (Radiographic Definition): lucency within a zone of pulmonary consolidation, a mass, or a nodule
    • Hence, a Lucent Area within the Lung that May or May Not Contain a Fluid Level and that is Surrounded by a Wall, Usually of Variable Thickness

Definitions Based on Wall Thickness

  • Cyst: ≤4 mm wall thickness at thickest point
  • Cavity: >4 mm wall thickness at thickest point (or with surrounding mass or infiltrate)


Mechanisms of Cavity Formation

  • Suppurative Lung Necrosis
    • Example: pyogenic lung asbcess
  • Caseous Lung Necrosis
    • Example: tuberculosis
  • Ischemic Lung Necrosis
    • Example: pulmonary infarction
  • Cystic Dilation of Lung Structures
    • Example: Pneumocystis jirovecii pneumonia and ball valve obstruction
  • Displacement of Lung Tissue by Cystic Structure
    • Example: Echinococcosis
  • Treatment-Related Necrosis
    • Example: malignancy
  • Internal Cyst Formation
    • Example: malignancy
  • Internal Desquamation of Tumor Cells with Subsequent Liquefaction
    • Example: malignancy

Probability of Malignancy

  • Wall Thickness: wall thickness is positively correlated with the probability of malignancy (although there is considerable overlap, so it is not a good discriminatory tool)
    • Wall Thickness <4 mm: 92% of lesions are benign
    • Wall Thickness >15 mm: 95% of lesions are malignant
  • Presence of Air-Fluid Level: presence of air-fluid level is not associated with the probability of malignancy

Etiology of Cystic Lesion

Congenital Cystic Lung Lesions

  • Bronchogenic Cyst (see Bronchogenic Cyst): approximately 33% are located within the lung parenchyma (usually within the lower lobes), although most are within the mediastinum
    • May contain air, fluid (with homogeneous appearance), or both
    • May become secondarily infected or impinge on other structures
  • Congenital Adenomatoid Malformation (see Congenital Adenomatoid Malformation): presents as cystic or solid lung mass, restricted to one part of the lung


  • Echinococcosis (see Echinococcosis): cystic lesions are more commonly multiple (than single), with wall thickness ranging in size from 2 mm-1 cm


  • Metastases to Lungs: rarely present with cystic lung lesions

Pneumatocele (see Pneumatocele)

General Comments

  • Definition: cystic airspace within the lung which characteristically increases in size over days-weeks (probably due to ball-valve air trapping mechanism), but eventually resolves

Infection-Associated Pneumatocele

Toxin-Associated Pneumatocele

Traumatic Pneumatocele


Etiology of Cavitary Lesion (Cavitary Infiltrate/Nodule)


  • Actinomycosis (see Actinomycosis)
  • Amebiasis (see Amebiasis)
  • Anaerobes (see Aspiration Pneumonia)
  • Blastomycosis (see Blastomycosis)
  • Chronic Pulmonary Aspergillosis (see Chronic Pulmonary Aspergillosis)
  • Clostridium Perfringens (see Clostridium Perfringens)
    • Epidemiology: associated with necrotizing, cavitary pneumonia and PE
  • Coccidioidomycosis (see Coccidioidomycosis)
  • Cryptococcosis (see Cryptococcosis)
    • Epidemiology: cavitation is more common in patients receiving steroids (as in HIV-related cases on PCP therapy)
  • Cytomegalovirus (CMV) (see Cytomegalovirus)
    • Epidemiology: may cavitate in HIV-related cases
  • Echinococcosis (see Echinococcosis)
    • Diagnosis: cystic lesions are more commonly multiple (than single), with wall thickness ranging in size from 2 mm-1 cm
  • Fusarium (see Fusarium)
    • Clinical: may present as pneumonia, cavitary lesions, or lung nodules (with/without a halo sign)
  • Gram-Negative Bacteria
  • Histoplasmosis (see Histoplasmosis)
    • XXXX
  • Invasive Pulmonary Aspergillosis (see Invasive Aspergillosis)
    • XXXX
  • Klebsiella Pneumoniae (see Klebsiella Pneumoniae)
    • Epidemiology: common etiology of cavitation (due to extensive pgenic lung necrosis)
  • Lomentospora Prolificans Infection (see Lomentospora Prolificans)
    • Epidemiology: xxxx
  • Lung Abscess (see Lung Abscess)
    • Epidemiology: cavitation is common
  • Melioidosis (see Burkholderia Pseudomallei)
    • XXXX
  • Mucormycosis (see Mucormycosis)
    • XXXX
  • Mycobacterium Abscessus (see Mycobacterium Abscessus)
    • Epidemiology: nodules/cavitation are common
  • Mycobacterium Avium Complex (MAC) (see Mycobacterium Avium Complex)
    • Epidemiology: nodules/cavitation are common
  • Mycobacterium Kansasii (see Mycobacterium Kansasii)
    • Epidemiology: nodules/cavitation are common
  • Mycobacterium Xenopi (see Mycobacterium Xenopi)
    • XXXX
  • Necrotizing Pneumonia (see Necrotizing Pneumonia and Pulmonary Gangrene)
    • XXXX
  • Nocardiosis (see Nocardiosis)
    • Epidemiology
      • XXXX
  • Paragonimiasis (see Paragonimiasis)
    • Epidemiology
      • XXXX
  • Pneumocystis Jirovecii (see Pneumocystis Jirovecii)
    • Epidemiology: cavitation is uncommon, but may occur in some cases
  • Rhodococcus Equi (see Rhodococcus Equi)
    • Epidemiology
      • XXXX
  • Scedosporiosis (see Scedosporiosis)
    • Risk Factors
    • Diagnosis
      • Upper Lobe Cavitary Infiltrates: may mimic those of chronic necrotizing aspergillosis
  • Septic Embolism (see Septic Embolism)
    • Diagnosis
      • Usually Multiple Well-Defined Pulmonary Nodules in Varying States of Cavitation
      • Usually 1-3 cm in Diameter
      • May be Accompanied by Subpleural Wedge-Shaped Infiltrates
  • Sporotrichosis (see Sporotrichosis)
    • Epidemiology
      • XXXX
  • Staphylococcus Aureus (see Staphylococcus Aureus)
    • Epidemiology
      • Common Cause of Necrotizing Pneumonia and Cavitation
  • Streptococcus (see Streptococcus)
  • Tuberculosis (see Tuberculosis):
    • Epidemiology
      • Cavitation is Common in Post-Primary TB Predominantly Involving the Upper Lobes
      • Tuberculosis is the Most Common Infection to Result in Cavitation: due to the extent of caseous necrosis
      • Presence of Comorbid Conditions (Such as Diabetes Mellitus, HIV Infection, and Anti-TNFα Therapy) Increase the Incidence of Smear Positivity, Cavitation, Treatment Failure, and Non-Tuberculosis-Related Death (Epidemiol Infect, 2015) [MEDLINE]
    • Diagnosis: cavity walls may be smooth or irregular
    • Clinical: tendency to form cavities enhances propagation of tuberculosis, since cavities contain large numbers of organisms which can be aerosolized and transmitted to other hosts


Primary Lung Neoplasm

  • Lung Cancer (see Lung Cancer): cavitation occurs in 10-15% of lung cancers
    • Epidemiology
      • Cavitation Occurs on 7-11% of Lung Cancers (by CXR) and 22% of Cases (by CT scan)
      • Cavitation is More Common in Squamous Cell Histology
      • Presence of Cavitation Portends a Worse Prognosis

Metastases to Lung

Pulmonary Vasculitis

  • Churg-Strauss Syndrome (see Churg-Strauss Syndrome)
    • Epidemiology
      • Infiltrates in Churg-Strauss Syndrome Rarely Cavitate
  • Rheumatoid Nodules (see Rheumatoid Arthritis)
    • Epidemiology
      • Rheumatoid Lung Nodules are Usually Associated with Rheumatoid Skin Nodules
    • Diagnosis
      • Usually Pleural or Subpleural
      • Associated with Interlobular Septae
      • Upper Lobe Predominance
      • More Commonly Multiple than Single
  • Wegener’s Granulomatosis (Granulomatosis with Polyangiitis, GPA) (see Wegener’s Granulomatosis)
    • Epidemiology
      • Approximately 10% of Cases have Cavitary Nodules
    • Diagnosis
      • More Commonly Multiple than Single


  • Acute Pulmonary Embolism With Pulmonary Infarction (see Acute Pulmonary Embolism)
    • Epidemiology
      • Pulmonary infarction occurs in <15% of PE cases, while only about 5% of pulmonary infarctions cavitate
  • Amiodarone (see Amiodarone)
    • Epidemiology
      • Amiodarone May Uncommonly Cause a Hyperdense Infiltrate/Mass Which May Cavitate
  • Amyloidosis (see Amyloidosis)
    • Epidemiology
      • Rare etiology of cavitation
  • Ankylosing Spondylitis (see Ankylosing Spondylitis)
    • Diagnosis: apical fibrobullous disease
  • Bronchiectasis (Localized) (see Bronchiectasis)
    • XXX
  • Chronic Berylliosis (see Beryllium)
    • XXXX
  • Congenital Adenomatoid Malformation (see Congenital Adenomatoid Malformation)
  • Crack Cocaine (see Cocaine)
    • XXXX
  • Cryptogenic Organizing Pneumonia (COP) (see Cryptogenic Organizing Pneumonia)
    • Clinical
      • Solitary Focal COP Pattern (Podule) Which May Cavitate
  • Langerhans Cell Histiocytosis (LCH) (see Langerhans Cell Histiocytosis)
    • Physiology
      • Serial HCRT suggests progression from nodules -> cavitating nodules -> cystic lesions
    • HRCT: upper zone cysts/honeycombing -> most cysts are <1 cm in diameter (however, large cysts may occur as disease progresses) with barely perceptible to few mm wall thickness
  • Lymphomatoid Granulomatosis (see Lymphomatoid Granulomatosis)
    • Clinical
      • Frequently presents with cavitation
  • Progressive Massive Fibrosis/Pneumoconiosis (see Progressive Massive Fibrosis)
    • Clinical
      • Irregularly-shaped fibrotic masses typically in upper lobes, which may cavitate (due to ischemic necrosis)
  • Pulmonary Sequestration (see Pulmonary Sequestration)
    • XXX
  • Sarcoidosis (see Sarcoidosis): aka Necrotizing Sarcoid Angiitis and Granulomatosis
    • Epidemiology
      • Cavitation Occurs in 6.8% of Cases

Etiology of Apical Fibrobullous Disease


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