Cavitary lesions of lung

Maj Manu Chopra

Cyst

• Air filled lesion

• Smooth and uniform wall > 1mm

• Epithelial lining +/-

• Infected cyst > surrounding lung inflammation > thick wall

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Cavity

• Air containing space

• Wall thickness > 1mm

• A lesion that has cavitated (regardless of wall thickness)

• 10% cancers cavitate (80% are Sq cell ca)

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How to define a cavity

a. Thickness of wallb. Smoothness / irregularity of inner liningc. Presence & character of contentsd. number

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Cavity wall

Thick • Acute lung abscess• Primary carcinoma• Metastic carcinoma• Wegeners granulomatosisThin• Chronic lung infection Thicker cavities are more often malignant

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Character of inner lining

• Nodular – carcinoma• Shaggy – acute lung abscess• Smooth – most of lung conditions

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Nature of contents

• Liquid - majority• Fungus ball – freely mobile• Echinococcus cyst – water lily sign• Pulmonary gangrene – sloughed, necrotic

iceberg

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Number of lesions

Solitary• Primary carcinoma• Ac lung abscess• Post traumatic lung cystMultiple• Metastatic neoplasm• Wegeners granulomatosis• Septic emboli

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Cavity

• Malignant lesions - Thick, nodular wall

• Benign lesions - Thin, smooth wall

• Wall thickness-

>15mm -85% malignant

5-15mm -75% benign

<5mm -95% benign

<1mm -malignancy rare

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Cavity

• Air fluid level- benign disease

• Focal thickening of cyst or cavity wall or fluid within cyst- s/o malignancy

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Air crescent sign

• Air outlining or capping the superior aspect of the mass or nodule within the cavity resulting in a crescent shaped collection of air

• Gravitational shift of the mass strongly suggests mycetoma and excludes carcinoma

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Supine

Prone

Air crescent sign

• Aspergilloma• Angioinvasive aspergillosis with septic infarction• Ca arising in a cyst• Cavitary ca• Clot in a cyst or cavity• Echinococcus• Mucous plug in cystic bronchiectasis• Papillomatosis• Pulm gangrene

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Cavitary lesions- common

1. Abscess of lung 2. Bronchogenic carcinoma 3. Bulla 4. Cystic bronchiectasis 5. Fungus disease

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Cavitary lesions- common

6. Honeycomb lung 7. Metastasis 8. Pneumatocele 9. Pneumocystis carinii pneumonia 10. Tuberculosis

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1.1. Abscess

• Localized infection >tissue destruction & necrosis

• Communication with tracheobroncheal tree >cavitation & air fluid level

• Inner wall -smooth/shaggy & irregular

• Wall thickness -5 to 15 mm

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1.1. Abscess

• Cause -Anaerobic inf, S aureus, P aeruginosa

• Often result of aspiration

• Infarction, cavitary neoplasm/ conglomerate mass

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1.1. Abscess

• CT-

-Densely enhancing wall- variable in thickness/ irregular in contour

-Internal wall- shaggy

-Contents- low attenuation

-Air fluid level may be seen

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22Pneumococcal pneumonia

23air-fluid level

Predisposing Factors for a Lung Abscess

• DEPRESSED GAG REFLEX

• UPPER AIRWAY INFECTION

• ESOPHAGOGASTRIC DISEASE WITH ASPIRATION

• PULMONARY DISEASE

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1.2.Carcinoma• Diam >2cm - 60%

• Upper lobes- 2/3rd

• Margin- ill defined, irregular, or spiculated

• Shape- irregular/lobulated

• Air bronchograms or bubbly lucencies (pseudocavitation)

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1.2.Carcinoma

• Cavitation with a thick(>15 mm) & nodular wall

• Satellite nodules absent• Calcification absent• Enhancement >15 HU • Doubling time 30 to 200 days

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33Sq cell Ca of bronchus

34Sq cell ca of bronchus

1.3.Bulla

o Thin-walled– <1 mm o air-filled space o Contained within the lung

o 1 cm in size when distendedo Walls may be formed by pleura, septa, or

compressed lung tissueUnilocular / multilocularPoorly ventilatedDecrease in size during ventilation 35

What a bulla isn’t

o Pneumatocoele

o Cavity

o Cyst

o Bleb

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Bulla

o Enlarge progressively over a period of months to years

o Most are associated with emphysema

o May become infected or lead to pneumothorax

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Imaging findings

o Seen more in upper lobes

o Thin-walled, sharply demarcated areas containing no visible blood vessels

o Only portion of wall is usually seen

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Imaging findings

o Tend to trap air

§ May become larger on expiration

o Bullae may become so large as to render the remaining normal lung almost invisible, pancaked atop the hemidiaphragm = vanishing lung syndrome

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Infected Bulla

o Differentiation from lung abscess

§ Bulla contains less fluid § Much thinner wall § No surrounding pneumonitis § Patients less sick

o Clearing may take weeks to months40

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1.4.Cystic bronchiectasis

• Multiple air filled cystic lesions• Thick/thin walled• Clustered • Lobar patchy or diffuse• Air fluid levels ( inf/retained secretions)• Air fluid levels at or about same height in all

the affected cysts with less fluid in the upper lobe cysts (water flows downhill)

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1.4.Cystic bronchiectasis

• CT-1.Increased bronchoarterial diameter >1 (signet

ring sign)2.Lack of tapering- airway diam unchanched for

2 cm distal to a branching point3.Contour abnormality- cluster of grapes4.Visibility of airways in peripheral 1cm of lung

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47Bronchiectasis

1.5.Semi invasive Aspergillosis

• In patients with low grade form of immuno-compromise (COPD, low dose cortico steroid, TB, DM, Collagen vascular disease)

• Tissue invasion and infarction over months

• Mimics appearance of active TB

• Irregular upper lobe consolidation and pleural thickening, slow progression to cavitation 48

49Semi-invasive Aspergillosis

1.5.Aspergilloma• Hyphae form a ball/mycetoma, lying free in

the cavity

• CXR- density surrounded by air within a cavity, best shown by CT (mobile intracavitary mass)-Air crescent sign

• Usually in upper lobes adjacent to pleura which almost always is thickened

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1.6.Honeycomb lung

• Reflects extensive lung fibrosis with alveolar destruction

• HRCT- thick walled air filled cysts, measuring 3mm to 1cm in diameter. Cysts share wall and occur in several layers at the pleural surface

• Associated findigs- reticular opacities, traction bronchiectasis

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54Honeycombing- idiopathic fibrosis

1.7.Metastasis

• 80%- Breast, skeleton and urogenital system

• The commonest primary tumours producing solitary pulmonary metastases- colon , kidney and breast, testicular tumours , bone Sarcomas and malignant melanoma

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1.7.Metastasis

• Cavitation more common in sq carcinomas and sarcomas

• Cavitation of a subpleural metastasis is a recognised cause of spontaneous pneumothorax

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57Metastases, carcinoma of cervix

1.8.Pneumatoceles

• Thin walled air filled space within lung occurs in assosciation with infection

• Haematogenous- septicaemia by S aureus, a common complication of i/v drug abuse

• Cavitation evident on later examination• Due to check valve mechanism• Causes – staph. aureus, pneumocystis carinii,• trauma

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59staph abscess, i/v drug abuser, thin-walled cavities, effusion

60staph tricuspid endocarditis, pneu-matoceles

61Staph bronchopneumonia, pneumatocele

1.9.Pneumocystis carinii

• Cavities, usually thin walled, occasionally up to several mm in thickness, may develop

• Appearances may return entirely to normal, some residual scarring and cyst formation is common

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1.10.Tuberculosis

• Post primary tuberculosis

• Start in the subapical parts of the upper lobes or in the apical segment of the lower lobes as small areas of exudative inflammation. These extend, coalesce, caseate and cavitate

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1.10.Tuberculosis

• Consolidation patchy and nodular and may be bilateral

• Progressive infection indicated by extension and coalescence of the areas of consolidation, and development of cavities

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1.10.Tuberculosis

• A large cavity with smaller satellite cavities, often bilateral but more advanced on one side

• Cavity walls are lined by tuberculous granulation tissue and traversed by fibrotic remnants of bronchi and vessels

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1.10.Tuberculosis

• Cavities- single/ multiple, large/ small and thin/ thick walled

• Fluid levels are sometimes visible

• Chronic cavities- colonised by Aspergilus and other fungi, and mycetomas may develop

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69Tuberculosis, complete destruction of the right lung

70Tuberculosis, bronchopneumonic spread to the opposite lung

71Aspergilloma , previous TB

2.Cavitary lesions- uncommon

1. Amyloidosis 2. Behçet syndrome 3. Cyst (eg, bronchial)4. Cystic adenomatoid malformation 5. Cystic fibrosis (mucoviscidosis)

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2.1.Amyloidosis

• A group of conditions characterised by extracellular deposition of fibrillary protien

• Multiple nodular angular opacities up to several centimetres in size and grow slowly- can cavitate or calcify

• Calcification- fine stippling

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2.1.Amyloidosis

• Alternatively diffuse reticulonodular shadowing or honeycombing due to diffuse deposition of amyloid within alveolar walls, lobular septa and pulmonary arterioles

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2.5.Cystic fibrosis

• Increased viscosity of the bronchial secretions- bronchial obstruction- air trapping/ predisposes to bronchiectasis

• CXR- signs of air trapping with flattening of the diaphragm, bowing of the sternum and increased dorsal kyphosis, and signs of bronchiectasis

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2.Cavitary lesions- uncommon

6. Diaphragmatic hernia 7. Langerhans cell histiocytosis 8. Hydatid cyst 9. Hydropneumothorax10. Inflammatory pseudotumors

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2.7.Langerhens cell histiocytosis

• Earliest- ill-defined transient patchy consolidation• Fine reticulonodular pattern throughout both

lungs, predominantly in the mid and upper zones• Confirmation with lung biopsy• HRCT – a mixture of discrete nodules and cystic

spaces• As fibrosis progresses, a coarser linear pattern

appears, with development of ring shadows, honeycombing and bullae

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2.8.Hydatid disease

• Echinococcal cyst

• Three layers:

(1) Pericyst/ adventitia formed of compressed host tissue

(2) Ectocyst friable middle layer

(3) Endocyst inner germinal layer from producing scolices

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2.8.Hydatid disease• Daughter cysts- formed if viability threatened,

but in the lung the cyst is unilocular

• Approx 20% of pulm cysts bilateral

• 10% associated with hepatic cysts

• Uncomplicated pulm hydatid cysts- well-circumscribed, round or oval, homogeneous masses, up to 10 cm in diam

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2.8.Hydatid disease

• Calcification rare

• Cysts may rupture into the pleura or bronchi

• Rupture into a bronchus- air-fluid level

• Ectocyst may separate from the adventitia so that a double walled cyst may be seen

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92Walls of the cavity have partly collapsed, fluid level

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Water-lily sign

Cudad LLL consolidation

2.14.Paragonimiasis

• Infected shellfish (Southeast Asia, esp Phillippines)

• Commonest reactions in the lung- formation of multiple 1-2 cm-diam cysts and broncho-pneumonic shadows which may resemble tuberculosis

• Dead flukes may calcify

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2.19.Rheumatoid pulmonary nodules

• Necrotic nodules are usually associated with subcutaneous nodules, and are similar histologically

• Well-defined, round opacities up to 7 cm in diameter and may be single or multiple and may cavitate

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2.19.Rheumatoid pulmonary nodules

• Caplan's syndrome- rheumatoid nodules against a background of pneumoconiosis

• The two diseases modify each other and numerous round opacities up to 5 cm in diameter, resembling metastases, may appear

• The solid fibrotic lesions eventually become hyalinised and may calcify

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106Rheumatoid disease, cavitating necrotic nodules

2.23.Wegener’s granulomatosis

• A necrotising vasculitis, involves the upper respiratory tract, the lungs and the kidneys

• A limited variant, confined to the thorax

• Symptoms referable to the upper air passages almost always present

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2.23.Wegener’s granulomatosis

• Cough, haemoptysis and pleurisy accompanied by constitutional symptoms of malaise, weakness and fever

• Rheumatoid and antinuclear factors are commonly found in the blood

• Inflammatory necrosis in the walls of small arteries and veins leading to occlusion of lumen

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2.23.Wegener’s granulomatosis

• Granulation tissue represents a reparative process- undergoes necrosis

• Necrotic granulation tissue forms rubbery pulmonary masses, which may be single or multiple up to several centimetres in diam, fairly well defined and often cavitate: they may resolve spontaneously, while new masses appear

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2.23.Wegener’s granulomatosis

• Cavitating lesions may have thick or thin walls, depending on how much of the necrotic material is expectorated

• Multiple cavities can closely mimic tuberculosis

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111Wegener's granulomatosis pulmonary masses

112Wegener's Granulomatosis, cavitating masses

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2.6. Diaphragmatic hernia

2.9.Hydropneumothorax

• A pneumothorax containing a horizontal fluid level which separates opaque fluid below from Iucent air above

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115Loculated pyo-pneumothorax

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Empyema

Abscess Empyema

Shape Round/ oval Oval/ lenticular/ crescentic

Angles with pleural surface

Acute Obtuse

Wall Irregular, thick Smooth, regular

Pulm vessel/ bronchi

entering wall/ center

displaced

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