HRCT IV

LINEAR AND RETICULAR
OPACITIES

NODULES AND NODULAR
INCREASED LUNG OPACITIES
ATTENUATION

PARENCHYMAL Consolidation
OPACIFICATION

Ground glass
HRCT PATTERN
CYSTIC
LESIONS, EMPHYSEMA, AND
BRONCHIEACTASIS

MOSAIC ATTENUATION AND
PERFUSION

DECREASED LUNG
ATTENUATION
AIR TRAPPING ON
EXPIRATORY SCANS

LINEAR AND RETICULAR
OPACITIES

NODULES AND NODULAR
INCREASED LUNG OPACITIES
ATTENUATION

PARENCHYMAL Consolidation
OPACIFICATION

Ground glass
HRCT PATTERN
CYSTIC
LESIONS, EMPHYSEMA, AN
D BRONCHIEACTASIS

MOSAIC ATTENUATION AND
PERFUSION

DECREASED LUNG
ATTENUATION
AIR TRAPPING ON
EXPIRATORY SCANS

 Lung cysts are defined as, well defined
, circumscribed air containing lesions with a
wall thickness of less than 4mm. They are
lined by usually fibrous or cellular
epithelium.

 Cavitiesare defined as radiolucent areas
with a wall thickness of more than 4mm and
are seen in infection
(TB, Staph, fungal, hydatid), septic
emboli, squamous cell carcinoma and
Wegener's disease.

 Common cause are :
1. Langerhans Histiocytosis
2. Lymphangiomyomatosis
3. Lymphoid interstitial
pneumonia

Multiple bizarre shaped cysts.There was an upper lobe
predominance.The patient had a long history of smoking.

40 year old female with no history of smoking . Multiple cysts that are
evenly distributed througout the lung ( in contrast to LCH).Notice the
pneumothorax.

Ehler Danlos Tuberous Sclerosis Pneumocystis

 Histopathological Considerations:
 Pulmonary Langerhans‟ cell histiocytosis (LCH) is a granulomatous
disorder which is strongly linked to cigarette smoking. The earliest
histologic abnormality is a proliferation of Langerhan‟s cells, around the
small airways; cellular nodules develop and become increasingly fibrotic
as the disease progresses. Nodules usually cavitate (often at different
times) and eventually give rise to cysts (often with unusual outlines).

 HRCT Appearances:
 The HRCT appearances depend on the stage of the disease. Not
surprisingly, in early disease, nodules will predominate. However, as
some nodules begin to cavitate there is evidence of a temporal
heterogeneity. The cysts of pulmonary LCH tend to be small (typically
less than 1cm in diameter) and may initially be thick-walled. The bizarre
outline of and distribution (mid and upper zonal with relative sparing of
the lung bases and the tip of the middle lobe/lingula) of cysts is a useful
diagnostic feature

Langerhans’ Cell Histiocytsosis: the early phase
is characterised by a nodular infiltrate.

This photomicrograph shows multiple cysts, the
largest of which has a bizarre shape
characteristic of late stage disease.

 Langerhans cell histiocytosis is also known as
pulmonary histiocytosis X or eosinophilic
granuloma.
LCH is probably an allergic reaction to
cigarette smoke since more than 90% of
patients are active smokers.
In the early nodular stage it is characterized
by a centrilobular granulomatous reaction by
Langerhans histiocytes.
In the cystic stage bronchiolar obliteration
causes alveolar wall fibrosis and cyst
formation.

 Early stage:
 Small irregular or stellate nodules in
centrilobular location.
 Late stage (more commonly seen)
 Cystic airspaces Cysts have bizarre shapes, they
may coalesce and than become larger.
 Upper and mid lobe predominance.
 Recurrent pneumothorax.

Multiple small nodules and cysts in a patient with
pulmonary Langerhans‟ cell histiocytosis. Note that
there is relative sparing of the middle lobe and
lingula.

“Honeycomb” lung in pulmonary Langerhans‟ cell
histiocytosis. Multiple thin-walled cysts of variable
size and some with bizarre outlines. Few nodules
are seen at this stage. stage.

On the left early stage Langerhans cell
histiocytosis with small nodules.
There are no cysts visible

ate stage Langerhans' cell histiocytosis. Cysts progress to typical
bizarre shaped cysts.

In a later stage the nodules start to cavitate and become
cysts.
These cysts start as round structures but finally coalesce to
become the typical bizarre shaped cysts of LCH.
In patients with LCH 95% have a smoking history.

On the left radiological pathological
correlation of Langerhans cell histiocytosis
in respectively nodular stage and early
and late cystic stage

pecimen of Langerhans cell histiocytosis
in three different stage

 On the left a chest film of a 19 year old patient with
Langerhans cell histiocytosis.
The dominant findig on the chest film is a reticular
patern and that's about as far as you can go.
There is also hyperinflation.
No way you would have recognized that this pattern
was caused by multiple cysts.
This is late stage Langerhans cell histiocytosis.
 The most challenging differential diagnosis in this
patient is centrilobular emphysema.
Emphysema however is defined as airspaces without
definable walls.
Usually we can identify the central dot sign.
The upper lobe predominance is not helpfull in the
differential as we can appreciate this in many
inhalational diseases and also in emphysema.

On the left another case of Langerhans'
cell histiocytosis.
It started as small noduli, which
progressed over time to cavitating
nodules.
In the end this will progress to bizarre
shaped cysts, that replace normal lung
tissue.

Langerhans cell histiosytosis: early phase and late phase

 Nodular LCH:
 Sarcoidosis: perilymphatic distribution.
 Metastases: random distribution.
 Cystic LCH:
 LAM: round cysts, evenly distribution in women
in the child-bearing age
 Cystic bronchiectasis: 'signet ring sign'.
 Centrilobular emphysema: no walls, central dot.
 LIP

 Emphysema, when it is severe, can mimick
Langerhans cell histiosytosis.
When it extends beyond the centrilobular
area to the edge of the secondary lobule, it
may look as if it is cystic with walls.
In patients with LCH, the pathologist may
find LCH, but also areas of
emphysema, respiratory bronchiolitis and
even fibrosis.
So these smoking-related diseases do not
represent discrete entities.

Histopathological Considerations:

Lymphangioleiomyomatosis (LAM) is a rare, idiopathic disorder occurring exclusively in females of child-bearing age. The cardinal histopathologic finding
is the abnormal proliferation of „immature‟ smooth muscle cells (so-called LAM cells) around the small airways, pulmonary vessels, lymphatics and alveolar
septa and account for the typical clinical features (recurrent pneumothoraces, chylous effusions and airflow obstruction). Interestingly, the pulmonary
abnormalities of LAM are similar to those seen in patients with tuberose sclerosis.

HRCT Appearances:
The striking finding on HRCT is of multiple thin-walled cysts of roughly uniform size. Unlike LCH, the cysts in LAM tend to be rounded
and uniformly distributed throughout the parenchyma with no regional sparing. Furthermore, there is a conspicuous absence (except in a
few rare reported cases) of nodules. Important ancillary diagnostic features include recurrent (chylous) pleural fluid and pneumothoraces.

Lymphangioleiomyomatosis characterised by
areas of smooth muscle proliferation (LAM cells)
which contribute to the wall of a typical cyst.

Rare disease, that occurs only in premenopausal women
Characterized by progressive proliferation of atypical muscle cells along the bronchioles leading to air trapping and the
development of thin-walled cysts, that replace normal lung parenchyma.
Identical pulmonary changes seen in 1% of patients with tuberous sclerosis (predominant involvement of young men).

Clinical findings:
Majority of patients present with dyspnea.
Chylous pleural effusions (40%), Pneumothorax (40%), hemoptysis (40%).
Patients die within 10 years of the onset of symptoms.
Pregnancy may exacerbate disease.

Numerous thin-walled cysts, surrounded by normal parenchyma.
Cysts range from 2mm to 5cm in diameter, are round in shape and more or less
uniform.
Cysts are distributed diffusely throughout the lungs and upper and lower lobes are
involved to a similar degree.
Wall thickness of the cysts ranges from barely perceptible to 4 mm.
Mediastinal or hilar adenopathy and pleural effusions (40%).
Recurrent pneumothorax (40%)

On the left a typical case of LAM with multiple evenly
spread thin walled cysts complicated by a
pneumothorax.

HRCT in a patient with lymphangioleiomyomatosis. Multiple thin-walled
cysts, of reasonably uniform size, are seen in both lungs; importantly, in
contrast to Langerhans‟ cell histiocytosis, there are no nodules.

Langerhans cell histiocytosis: > 90% are smokers, cysts have irregular shapes and the
basal costophrenic angles are spared.
Centrilobular emphysema: characterized by airspaces that have no perceptible
wall, centrilobular artery seen as dot in the centre.
Lymphoid interstitial pneumonitis: seen in patients with HIV and Sj?gren syndrome.

 Permanent dilatation of the air spaces distal to
terminal bronchiole, accompanied by destruction of
their alveolar walls without obvious fibrosis
 Emphysema typically presents as areas of low
attenuation without visible walls as a result of
parenchymal destruction.

 Most common type
 Strongly associated with
smoking.
 Often the centrilobular artery
is visible within the centre of
these lucencies.
 Most commonly in the upper
lobes

48

Centrilobular emphysema due to smoking. The
periphery of the lung is spared (blue arrows).
Centrilobular artery (yellow arrows) is seen in the
center of the hypodense area

Centrilobular artery (arrows) in many of the low-attenuating
areas.

Histologic specimen shows areas of lung destruction surrounding a
small centrilobular artery (arrow)

 Affects the peripheral parts
of the secondary pulmonary
lobule adjacent to the
pleura and interlobar
fissures

 Produces subpleural
lucencies.

 Can be isolated
phenomenon in young
adults, or in older patients
with centrilobular
emphysema

52

 Paraseptal emphysema is localized near
fissures and pleura and is frequently
associated with bullae formation (area of
emphysema larger than 1 cm in diameter).
 Apical bullae may lead to spontaneous
pneumothorax

Paraseptal emphysema with small bullae

Paraseptal emphysema Honeycomb cysts

Occur in a single layer at the May occur in several layers in the
pleural surface subpleural lung

Predominate in the upper lobes Predominate at the lung bases

Unassociated with significant Asso with other findings of
fibrosis fibrosis.

Associated with other findings of -
emphysema

57

 Affects the entire secondary
pulmonary lobule with
complete destruction of the
entire pulmonary lobule.
 Results in an overall decrease in
lung attenuation
 Reduction in size of pulmonary
vessels
 Lower lobe predominance

 In alpha-1-antitrypsin
deficiency, but also seen in
smokers with advanced
emphysema

58

Alpha-1-antitrypsin deficiency

• Does not represent a specific histological
abnormality
• Emphysema characterized by large bullae
• Often associated with centrilobular and
paraseptal emphysema

Previously known as irregular or cicatricial emphysema
 can be seen in association with fibrosis
 with silicosis and progressive massive fibrosis or
 sarcoidosis

63

Centrilobular Panlobular Paraseptal
emphysema emphysema emphysema
• Most common type • Affects the whole • Adjacent to the
• Irreversible secondary lobule pleura and
destruction of • Lower lobe interlobar fissures
alveolar walls in predominance • Can be isolated
the centrilobular • In alpha-1- phenomenon in
portion of the antitrypsin young adults, or in
lobule deficiency, but older patients with
• Upper lobe also seen in centrilobular
predominance and smokers with emphysema
uneven advanced • In young adults
distribution emphysema often associated
• Strongly with spontaneous
associated with pneumothorax
smoking.

 A sharply demarcated area of emphysema ≥ 1 cm
in diameter

 A thin epithelialized wall ≤ 1 mm.

 Uncommon as isolated findings, except in the
lung apices

 Usually associated with evidence of extensive
centrilobular or paraseptal emphysema

 When emphysema is associated with
predominant bullae, it may be termed bullous
emphysema
67

A thin-walled, gas-filled space within the
lung,
 Associated
with acute pneumonia or
hydrocarbon aspiration.
• Often transient.
• believed to arise from lung necrosis and
bronchiolar obstruction.
• Mimics a lung cyst or bulla on HRCT and
cannot be distinguished on the basis of HRCT
findings.

68

 Thicker and more irregular walls than lung
cysts
.
• In diffuse lung diseases - LCH, TB, fungal
infections, and sarcoidosis.

 Also
seen in rheumatoid lung disease, septic
embolism, pneumonia, metastatic
tumor, tracheobronchial papillomatosis, and
Wegener granulomatosis

70

Is the abnormal dilatation of the medium-sized
bronchi (>2 mm in diameter) caused by destruction of
the muscular and elastic components of bronchial
walls. The proximal bronchi are less affected because
they have more cartilage and are more resistant to
dilation.

75

 Bronchial dilatation
# The broncho-arterial ratio (internal diameter
of the bronchus /pulmonary artery) exceeds 1.
# In cross section it appears as “signet ring
appearance”

 Lack of bronchial tapering
# the earliest sign of cylindrical bronchiectasis
# One indication is lack of change in the size of an
airway over 2 cm after branching.

 Visualization of peripheral airways
# Visualization of an airway within 1 cm of the
costal pleura is abnormal and indicates potential
bronchiectasis
76

Gross pathologic lung specimen from a patient with bronchiectasis. Notice the small
pulmonary artery abutting the much larger dilated bronchus (arrow), both of which
are seen on a cross-sectional view.

# Bronchial wall thickening : normally wall of bronchus
should be less than half the width of the
accompanying pulmonary artery branch.

# Mucoid impaction

# Air trapping and mosaic perfusion

84

mild to severe signs of bronchiectasis (curved arrows) and mild to
moderate signs of bronchial wall thickening. In addition, CT scan shows
mucous plugging (straight arrows) and mosaic perfusion (∗).

Extensive, bilateral mucoid impaction. Mosaic perfusion caused by
large and small airway obstruction. Small centrilobular nodules are
visible in the right lower lobe

 Cylindrical Bronchiectasis

 Varicose Bronchiectasis

 Cystic Bronchiectasis

 Traction Bronchiectasis

# mildest form of this
disease,
# thick-walled bronchi
that extend into the
lung periphery and
fail to show normal
tapering

88

# beaded appearance of
bronchial walls - dilated
bronchi with areas of
relative narrowing
# string of pearls.
# Traction bronchiectasis
often appears varicose.

# Group or cluster of air-
filled cysts,
# cysts can also be fluid
filled, giving the
appearance of a cluster
of grapes.

# Defined as dilatation of
intralobular bronchioles
because of surrounding
fibrosis
# due to fibrotic lung
diseases

92

1. Infective : childhood
pneumonia,pertusis, measles, tuberculosis
2. Non- infective causes : Bronchopulmonary
aspergillosis, inhalation of toxic fumes
3. Connective tissue disorder : Ehlers-Danlos Synd,
Marfan synd , tracheobronchomeglay
4. Ciliary diskinesia : Cystic fibrosis, Kartangener
synd, agammaglobulinemia .
5. Tractional bronchiectasis in interstitial fibrosis.

6. Bronchial obstruction: with endobronchial
tumors, broncholithiasis, and foreign body aspiration.

95

• Emphysema:
areas without walls

• Cyst:
discrete, thin walls

• Honeycombing:
multiple subpleural cysts arranged in rows

MOSAIC ATTENUATION
AND PERFUSION

• Definition: Heterogeneous lung density with areas
of
“groundglass attenuation” alternating with areas of
“decreased” lung density usually having a zonal or
geographic pattern of distribution

 Mosaic perfusion refers to areas of decreased
attenuation which results from regional
differences in lung perfusion secondary to
airway disease or pulmonary vascular
disease.
 The pulmonary arteries will be reduced in
size in the lucent lung fields thus allowing
mosaic perfusion to be distinguished from
ground-glass opacities.

 Lungdensity and attenuation depends
partially on amount of blood in lung tissue.

 May be due to
 vascular obstruction,
 abnormal ventilation or
 airway disease

105

 Patchy ground glass infiltrates resulting from
airspace/interstitial disease: eg PCP
 Air-trapping resulting from large and small airway
obstruction: eg constrictive bronchiolitis
 Vascular disease: eg. chronic embolic PHT

 Parenchymal disease: high attenuation regions are
abnormal and represent ground-glass opacity
 Obstructive small airways disease: low attenuation
regions are abnormal and reflect decreased
perfusion of the poorly ventilated regions, e.g.
Bronchiectasis, cystic fibrosis,constrictive
bronchiolitis
 Occlusive vascular disease: low attenuation regions
are abnormal and reflect relative oligaemia
e.g. Chronic pulmonary embolism

 Peripheral Vessels : if vessels in
hypoattenuated regions of the lung are
smaller than in the other regions, the
pattern is due to mosaic perfusion (i.e.
airways or vascular disease rather than
ground-glass)
 Central Vessels : pulmonary
hypertension, reflected as dilatation of the
central pulmonary arteries, suggests a
vascular cause
 Small Airways : the presence of abnormally
dilated or thick walled airways in the
relatively lucent lung confirms underlying
airway disease

 Parenchymal Changes : ground glass opacity
is the likely cause for mosaic attenuation if
other features of infiltrative disease are
present, such as reticular opacities
(i.e. crazy paving pattern) or nodules
 Air Trapping : refers to regions of lung which
following expiration do not show the normal
increase in attenuation, or show little change
in cross-sectional area (i.e., this is an
expiratory HRCT finding). The presence of
air trapping suggests airway disease

# Areas of increased attenuation have relatively large
vessels, while areas of decreased attenuation have
small vessels.
# Air trapping and bronchial dilatation commonly
seen.
# Causes include: Bronchiectasis, cystic fibrosis and
bronchiolitis obliterans.

110

# decreased vessel size in less opaque regions is often
visible
# common in patients with acute or chronic
pulmonary embolism (CPE),

MOSIAC PATTERN

DEPENDENT LUNG ONLY NONDEPENDENT LUNG

EXPIRATION
PRONE
POSITION

NO AIR
TRAPPING
AIR
TRAPPING
RESOLVE NOT RESOLVE

VESSEL SIZE

PLATE GROUND
ATELECTASIS GLASS
AIRWAYS
DECREASED NORMAL DISEASE

GROUND
VASCULAR GLASS

112

 Air-space Disease
 Pcp, Edema
 Interstitial Disease
 Fibrosis/Microscopic
 Honeycombing
 Combined Air-space / Interstitial
Disease

 Large airway disease
 Bronchiectasis
 Small airway disease
 Constrictive bronchiolitis
 Asthma

Air trapping on expiratory imaging in the absence of inspiratory
scan findings in a patient with bronchiolitis obliterans.

 Chronic pulmonary embolism
 Pulmonary hypertension
 2° increased pulmonary pressure

Mosaic perfusion pattern with marked regional variations in attenuation of
the lung parenchyma and disparity in the size of the segmental vessels,
with larger-diameter vessels in regions of increased attenuation (arrows). A
peripheral parenchymal band or scar (arrowhead) from infarction also is
depicted.

mosaic lung attenuation, with segmental and subsegmental
perfusion defects. A small pleura-based opacity (arrowhead)
caused by previous infarction is seen in the apical segment
of the right lower lobe.

Mosaic Algorithm

Air trapping

Small Small
Airways Vessel

 It refers to mixed densities
which includes
# consolidation
# ground glass opacities
# normal lung
# Mosaic perfusion

• Signifies mixed infiltrative
and obstructive disease

Common cause are :

1. Hypersensitive pneumonitis

2. Sarcoidosis

3. DIP

144

Headcheese sign in
hypersensitivity
pneumonitis.

HRCT scan shows
lung with a
geographic
appearance, which
represents a
combination of
patchy or lobular
ground-glass
opacity (small
arrows) and mosaic

Upper lung zone preference is seen in:

1.Inhaled particles: pneumoconiosis (silica or coal)
2.Smoking related diseases (centrilobular
emphysema
3. Respiratory bronchiolitis (RB-ILD)
4.Langerhans cell histiocytosis
5.Hypersensitivity pneumonitis
6.Sarcoidosis

149

Lower zone preference is seen in:

1. UIP
2. Aspiration
3. Pulmonary edema

150

Central Zone VS. Peripheral zone

1. Sarcoidosis 1. COP
2. Bronchitis 2. Ch Eosinophilic
3. Cardiogenic pulmonary Pneumonia
edema 3. UIP
4. Hematogenous mets

152

# In sarcoidosis the common pattern is right
paratracheal and bilateral hilar adenopathy
('1-2-3-sign').

154

# In sarcoidosis the common pattern is right
paratracheal and bilateral hilar adenopathy
('1-2-3-sign').

# In lung carcinoma and lymphangitic
carcinomatosis adenopathy is usually
unilateral.

#'Eggshell calcification' in lymph nodes occurs
in: Silicosis and coal-worker's pneumoconiosis
and is sometimes seen in sarcoidosis, post
irradiation Hodgkin disease, blastomycosis
and scleroderma .
156

 Pulmonary edema

 Lymphangitic spread of carcinoma - often
unilateral

 Tuberculosis

 Lymphangiomyomatosis (LAM)

 Asbestosis

159

 Ground glass
 •Lobular areas of lower attenuation
 •Normal lung parenchyma
 •Normal lung volumes
 •No architectural distortion
 •No nodules
 •No reticulation

 Main differential diagnosis on imaging
 –Subacute Hypersensitivity Pneumonitis
 –Atypical Infection with associated
bronchiolitis
 –Nonspecific Interstitial Pneumonia (NSIP)
 –Sarcoidosis

 Minor subpleural lung reticulation
 •Minimal architectural distortion with fine
honeycomb lung (Right Upper Lobe for
example)+/-traction bronchiectasis
bronchiolectasis
 •No significant ground glass remote from
areas of involvement

 Upper, mid and lower zonal distribution
 •Mild heterogeneity of lung parenchyma
 •Pattern of reticulation extends to the
pleura with no subpleural lung sparing
 •No nodules
 •No consolidation
 •Difficult to comment on lung volumes on
study provided scout suggest slight loss of
volume

 Main differential diagnosis on imaging:
 –Early Idiopathic Pulmonary Fibrosis of a UIP
pattern
 –Chronic Hypersensitivity Pneumonitis
 –Pulmonary manifestation of collagen
vascular disease in a Fibrotic pattern of NSIP
 –Pulmonary manifestation of drug reaction
 –Sarcoidosis

 Idiopathic Pulmonary Fibrosis /Usual
Interstitial Pneumonia (IPF/UIP)
 •Nonspecific Interstitial Pneumonia (NSIP)
 •Hypersensitivity Pneumonitis
 –Acute
 –Subacute
 –Chronic
 •Drug reaction

 Specific form of chronic fibrosing interstitial
pneumonia limited to the lung and associated
with the histologic appearance of Usual
Interstitial Pneumonia (UIP)
 •Temporal and geographic heterogeneity
 •UIP can also be seen in
 –Asbestosis
 –Chronic Hypersensitivity Pneumonitis
 –Drug induced disease
 –Familial IPF

 Usually symmetric
 •Basal predominant but may be diffuse
 •Irregular
 •Linear
 •May progress to reticulonodular pattern
 •Progress to volume loss
 •In smokers volumes can be normal

 Subpleural distribution
 •Lower lung zone predominant
 •Architectural distortion
 •Irregular intralobular lines
 •Traction bronchiectasis
 •Honey comb lung cysts
 •Air filled cysts

 •5% can be upper lung predominant
 •Ground glass is mild
 •Associated with fibrosis
 •Fewer ground glass opacities remote from
fibrosis
 •Disease activity vs. fibrosis

 Emphysema in 30%
 •Pulmonary ossification
 •Lymph node enlargement
 •No centrilobular or peribronchovascular
nodules
 •No extensive consolidation
 •No extensive ground glass opacities

 Idiopathic Pulmonary Fibrosis IPF
 •Main differential diagnosis
 –Fibrotic NSIP +/-relation to connective
tissue disease
 –Asbestosis
 –Chronic Hypersensitivity

 •Hazy opacities mainly middle and lower
lung zones
 •+/-reticular opacities
 •Can be normal

•Bilateral symmetric ground glass opacities
•Fine reticular opacities
•When only ground glass opacities cellular
form most likely

•Subpleural lung sparing may be distinguishing
feature compared to UIP
•Honeycomb lung much less common than UIP

 •Subpleural lung sparing may be
distinguishing feature compared to UIP
 •Honeycomb lung much less common than
UIP

•Differential Diagnosis
–Hypersensitivity pneumonitis
–Cryptogenic organising pneumonia
–IPF

 Chronic eosinophilic pneumonia with peripheral
areas of ground glass opacity.

 Sarcoid end-stage with massive fibrosis in upper
lobes presenting as areas of consolidation.
Notice lymphadenopathy.

 Chronic eosinophilic pneumonia with peripheral
areas of consolidation.

 Broncho-alveolar cell carcinoma with both areas
of ground glass opacity and consolidation

 Lymphangiomyomatosis (LAM): uniform cysts in
woman of child-bearing age; no history of
smoking; adenopathy and pleural effusion;
sometimes pneumothorax.

 LCH: multiple round and bizarre shaped cysts;
smoking history.

 Honeycombing

 Centrilobular emphysema: low attenuation areas
without walls.

 Centrilobular emphysema: low attenuation areas
without walls. Notice the centrilobular artery in
the center.

 Langerhans cell histiocytosis (LCH): multiple
thick walled cysts; smoking history.

 Honeycombing.

 Lymphangiomyomatosis (LAM): regular cysts in
woman of child-bearing ag

35 yr old smoker with progressive
dyspnea. What is the most likely dx?
1. Infectious
bronchiolitis
2. LAM
3. Thyroid cancer
4. Sarcoid
5. LCH

 There are multiple areas of consolidation.
Ancillary findings are hilar and mediastinal
lymphadenopathy.

 The differental diagnosis of the CT-images is
basically the same as of the chest film.
Histology revealed alveolar sarcoid.
There is only one clue to the diagnosis and that
is the presence of small nodules that can be
identified in image 3, but these are difficult to
see.
This case nicely demonstrates that sarcoidosis
truely is 'the great mimicker'.
Sarcoidosis should be therefore in our
differential diagnostic list!.

Chronic EAA: there is a mosaic attenuation pattern. Within areas of ground-
glass opacification there is traction bronchiectasis and parenchymal
distortion. The areas of apparently spared “black” lung show a diminution in
the number/calibre of pulmonary vessels (indicating small airways disease)

Key Features
Idiopathic Pulmonary Fibrosis Basal and subpleural reticular pattern with
honeycombing ± traction bronchiectasis
Sarcoidosis

Acute Well-defined bronchocentric and subpleural micronodules. Symmetrical
enlarged hilar/mediastinal lymph nodes (with or without calcification)

Chronic Coarse bronchocentric upper lobe fibrosis
Hypersensitivity Pneumonitis

Subacute Ill-defined centrilobular nodules, ground-glass opacification and (lobular)
foci of decreased attenuation (with air-trapping on expiratory CT)

Chronic Diffuse ground-glass opacification, traction bronchiectasis and
parenchymal distortion. Lobular areas of air-trapping
Langerhans’ Cell Histiocytosis Nodules ± cavitation bizarre-shaped, thin-walled cysts. Sparing of
extreme lung bases and tip of middle lobe/lingula

Lymphangioleiomyomatosis Uniform thin-walled cysts; no zonal sparing/no nodules

Lymphocytic Interstitial Pneumonia Ground-glass opacification, nodules, thin-walled cysts

Alveolar Proteinosis Patchy (geographical) ground-glass opacification and thickened
interlobular septa (“crazy-paving” pattern)

 Major Criteria–
 Exclusion of otherknown etiologies
 – Abnormal PFT’S
 – Abn HRCT > 6 mos
 – TBBX/BAL excluding other etiologies
 Minor Criteria
 – Age > 50 yrs
 – Insidious onset DOE
 – Diagnosis > 3 mos duration
 – Bibasilar rales
 In absence of OLB: Dx requires all 4 major - 3/4minor
criteria

 Lymphocytic interstitial pneumonitis or LIP is
uncommon, being seen mainly in patients with
autoimmune disease, particularly Sj?gren's
syndrome, and in patients with AIDS.
Symptoms are nonspecific and often those of the
patient's underlying disease

 HRCT findings are usually nonspecific.

 Histopathological Considerations:
 Lymphocytic interstitial pneumonia (LIP) is a clinicopathological term for a
pulmonary lymphoproliferative abnormality associated with several disease
entities including dysproteinaemic states, connective tissue disorders and HIV
infection. Is is noteworthy that idiopathic LIP is exceedingly rare. On histologic
examination there is a interstitial cellular infiltrate comprising small, mature
lymphocytes and plasma cells.

 HRCT Appearances:
 Admittedly, the HRCT appearances of LIP, may be wholly non-specific: in
individual patients, variable combinations of ground-glass
opacification, nodules (ill-defined centrilobular or subpleural) and
thickening of the interlobular septa, are typical. However, in
some patients with LIP, the above features may be associated with thin-
walled cysts. Furthermore, in some patients with Sjögren‟s
syndrome, there may be (calcified) deposits of amyloid in addition to thin-walled
cysts.

Lymphocytic interstitial pneumonia: there is a
diffuse interstitial infiltrate of lymphocytes, most
marked around the bronchovascular bundles
and thickening of alveolar walls.

On the left a patient with Sjogren's syndrome with LIP

Lymphocytic interstitial pneumonia in Sjögren‟s syndrome. In addition to
the diffuse ground-glass opacification there are multiple thin-walled cysts in
both lungs. At least two irregular nodules (arrows), representing amyloid
deposition, are noted in the right lower lobe

On the left three different patients with lung cysts.
From left to right: Lymphangiomyomatosis, LIP and Langerhans cell
histiocytosis.

HRCT IV

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HRCT IV

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