This document discusses several common interstitial lung diseases. It begins with an overview and then focuses on sarcoidosis, describing its typical radiological presentation including small nodules in a perilymphatic distribution and stages of disease. Other diseases discussed include silicosis, lymphangitic carcinomatosis, pulmonary edema, hypersensitivity pneumonitis, tuberculosis, and chronic eosinophilic pneumonia. For each disease, the document outlines key radiological findings on HRCT and chest x-ray and provides differential diagnoses.

1. InterstIal lung dIseases
Dr. Shrikant Nagare

2. Introduction
• Interstitial lung diseases (ILD’s)represent a
large number of conditions that involve the
parenchyma of lung- the alveoli, the alveolar
epithelium, the capillary endothelium, and the
spaces between these structures, as well as
perivascular and lymphatic tissues.

3. • There are numerous interstitial lung diseases,
but in clinical practice only about ten diseases
account for approximately 90% of cases.
• Knowledge of both, the radiological and
clinical appearance of these more common
interstitial lung diseases, is therefore
important for recognizing them in the daily
practice and including them in the differential
diagnosis.

5. Sarcoidosis
• Sarcoidosis is a systemic disorder of unknown origin.
It is characterized by non-caseating granulomas in multiple
organs, that may resolve spontaneously or progress to
fibrosis.
• Pulmonary manifestations are present in 90% of patients.
• Less than 5% of patients die from sarcoidosis usually as a
result of pulmonary fibrosis.

6. Sarcoidosis

7. Sarcoidosis
• Stages:
Chest films in sarcoidosis have been classified into
four stages:
I. Bilateral hilar lymphadenopathy
II. Bilateral hilar lymphadenopathy + pulmonary disease
III. Only pulmonary disease
IV. Irreversible fibrosis
These stages do not indicate disease chronicity or
correlate with changes in pulmonary function.

8. • Patient with stage I disease.
There is hilar and paratracheal adenopathy and no sign of
pulmonary involvement.

9. HRCT findings in Sarcoidosis.
• Common findings:
– Small nodules in a perilymphatic distribution (i.e. along
subpleural surface and fissures, along interlobular septa and the
peribronchovascular bundle).
– Upper and middle zone predominance.
– Lymphadenopathy in left hilus, right hilus and paratracheal (1-2-
3 sign). Often with calcifications.
• Uncommon findings:
– Conglomerate masses in a perihilar location.
– Larger nodules (> 1cm in diameter, in < 20%)
– Grouped nodules or coalescent nodules surrounded by multiple
satellite nodules (Galaxi sign)
– Nodules so small and dense that they appear as ground glass or
even as consolidations (alveolar sarcoidosis)

10. Sarcoidosis: typical presentation with nodules along the bronchovascular
bundle and the fissures
Notice the partially calcified node in the left hilum.

11. A detailed view with the
typical HRCT-presentation
with nodules along
bronchovascular bundle (red
arrow) and fissures (yellow
arrow).
This is the typical
perilymphatic distribution of
the noduless.

12. Another typical presentation of sarcoidosis with mediastinal lymphadenopathy
and small nodules in a perilymphatic distribution along bronchovascular bundles
and along fissures (yellow arrows).
Always look for small nodules along the fissures, because this is a very specific and
typical sign of sarcoidosis.

13. Fibrosis in Sarcoidosis
• Progressive fibrosis in sarcoidosis may lead to
peribronchovascular (perihilar) conglomerate masses
of fibrous tissue.
The typical location is posteriorly in the upper lobes,
leading to volume loss of the upper lobes with
displacement of the interlobar fissure.
Other diseases that commonly result in this appearance
are:
• Silicosis
• Tuberculosis
• Talcosis

14. Sarcoidosis with conglomerate masses of fibrous tissue

15. A typical chest film of long standing
sarcoidosis (stage IV) with fibrosis in the
upper zones and volume loss of the upper
lobes resulting in hilar elevation.
Fibrosis results in obliteration of pulmonary
vessels, which can lead to pulmonary
hypertension.
Sarcoidosis with fibrosis in the upper lobes.
Typical chest film.

16. Alveolar Sarcoidosis
In this case the appearance resembles a
ground glass attenuation, but with a close look
you may appreciate that the increased
attenuation is the result of many tiny grouped
nodules.
Also notice the hilar lymphadenopathy

17. • A case of fibrosing sarcoidosis, showing fibrosis, traction
bronchiectases and crowding of the involved bronchi,
predominantly in the perihilar region and upper lobes.
Nodular abnormalities are absent, but the appearance
and the location of the fibrosis are very suggestive of the
diagnosis of sarcoidosis.

18. Differential diagnosis of Sarcoidosis
• Lymphadenopathy:
– Primary TB: asymmetrical adenopathy
– Histoplasmosis
– Lymphoma
– Small cell lung cancer with nodal metastases
• Nodular pattern:
– Silicosis / Pneumoconiosis: predominantly centrilobular and subpleural
nodules.
– Miliary TB: random nodules.
• Fibrotic pattern:
– Usual Interstitial Pneumonia (UIP): basal and peripheral fibrosis,
honeycombing.
– Chronic Hypersensitivity Pneumonitis: mid zone fibrosis with mosaic pattern.
– Tuberculosis (more unilateral).

19. Silicosis / Coal worker
pneumoconiosis
• Silicosis and Coal worker pneumoconiosis (CWP) are
pathologically distinct entities with differing histology,
resulting from the inhalation of different inorganic dusts.
• The radiographic and HRCT appearances of these diseases,
however, may not be distinguishable from each other and
may be similar to sarcoidosis.
• Silicosis and CWP occur in a specific patient group
(construction workers, mining workers, workers exposed to
sandblasting, glass blowing and pottery).

20. HRCT findings in Silicosis/CWP
• Small well-defined nodules of 2 to 5mm in diameter in both
lungs.
• Upper lobe predominance
• Nodules may be calcified
• Centrilobular and subpleural distribution
• Sometimes random distribution
• Irregular conglomerate masses, known as progressive massive
fibrosis
• Masses may cavitate due to ischemic necrosis.
• Often hilar and mediastinal lymphnodes.

21. A case of silicosis showing nodules of varying sizes with a
random and subpleural distribution. One nodule contains
calcification (arrow).
Note the absence of a lymphatic distribution pattern
(peribronchovascular and along fissures), which would be
suggestive of sarcoidosis.

22. Differential diagnosis of Silicosis /
Pneumoconiosis
• Sarcoidosis : can be difficult to distinguish (look for
distribution of nodules).
• Infection: miliary TB, fungus.
• Hematogenous metastases: silicotic nodules in subpleural
and peribronchiolar location up to the level of the secondary
pulmonary lobule, may have a seemingly random distribution
and simulate metastases and miliary infections.
• Langerhans cell histiocytosis: can be difficult to distinguish
from silicosis in the early stage, when LCH is solely
characterized by the presence of small nodules. Look for
nodules with cavitation.

23. Lymphangitic Carcinomatosis
• Lymphangitic Carcinomatosis results from
hematogenous spread to the lung, with subsequent
invasion of interstitium and lymphatics.
• Lymphangitic Carcinomatosis is seen in carcinoma of
the lung, breast, stomach, pancreas, prostate, cervix,
thyroid and metastatic adenocarcinoma from an
unknown primary.

24. HRCT findings in Lymphangitic
Carcinomatosis
• Interlobular septal thickening, thickening of fissures
and thickening of the peribronchovascular interstitium
(bronchial cuffing).
• Depending on filling with fluid or with tumor cells,
septal thickening is irregular or smooth.
• Focal or unilateral abnormalities in 50% of patients.
• Hilar lymphadenopathy in 50% of patients.
• Pleural effusion due to pleuritic carcinomatosis ( > 50%
of patients).

25. A patient with Lymphangitic Carcinomatosis.
Notice the focal distribution.
This finding is helpful in distinguishing Lymphangitic Carcinomatosis from other
causes of interlobular septal thickening like pulmonary edema or sarcoid.
There is also lymphadenopathy.

26. Differential diagnosis of Lymphangitic
Carcinomatosis
Diseases showing septal thickening:
• Cardiogenic pulmonary edema:
bilateral abnormalities, filling of
alveoli, enlarged heart, rapid
response to diuretics, ground-glass
opacity due to filling of alveoli with
fluid, gravitational distribution of
the alveolar fluid.
• Alveolar proteinosis: sharply
demarcated secondary lobules with
ground glass attenuation as
opposed to secondary lobules with
normal aeration, superimposed
inter and intralobular septal
thickening (crazy paving).

27. Cardiogenic pulmonary edema
• Patients with pulmonary edema are not
imaged with HRCT as their diagnosis is usually
based on a combination of clinical and chest
radiographic findings.
However sometimes the diagnosis is not that
straightforward and knowledge of the HRCT
appearance of pulmonary edema can be
helpful in avoiding misdiagnosis.

28. HRCT findings in cardiogenic
pulmonary edema
• Bilateral septal thickening and ground-glass
opacity.
• Perihilar and gravitational distribution
predominatly in the dependent lung.
• Cardiomegaly and pleural fluid.

29. Cardiogenic pulmonary edema
• Typical features of cardiogenic
pulmonary edema
There is smooth septal
thickening and some ground
glass opacity in the dependent
part of the lungs.
In addition there is bilateral
pleural fluid.
In a patient with a known
malignancy lymphangitic
carcinomatosis would be high
in the differential diagnostic
list.

30. Differential diagnosis of cardiogenic
pulmonary edema.
• Lymphangitic carcinomatosis
• Interstitial pneumonia (viral, mycoplasma)
• ARDS
• Pulmonary hemorrhage

31. Hypersensitivity Pneumonitis
• Hypersensitivity pneumonitis (HP) is also known as
extrinsic allergic alveolitis (EAA).
HP is an allergic lung disease caused by the inhalation
of a variety of antigens (farmer's lung, bird fancier's
lung, 'hot tub' lung, humidifier lung).
• The radiographic and pathologic abnormalities in
patients can be classified into acute, subacute, and
chronic stages.
• Mostly HRCT is performed in the subacute stage of HP,
weeks to months following the first exposure to the
antigen or in the chronic phase.

32. Subacute hypersensitivity
pneumonitis
• The key findings in the subacute hypersensitivity
pneumonitis are:
• ill-defined centrilobular nodules of ground-glass
opacity (80% of cases) or
• mosaic pattern of a combination of patchy ground-
glass opacity due to lung infiltration and patchy
lucency due to bronchiolitis with air trapping

33. Subacute hypersensitivity pneumonitis with ill-defined
centrilobular nodules
Case with subacute hypersensitivity pneumonitis with a typical mosaic pattern and
without any signs of septal thickening or distortion of the airways.

34. Subacute hypersensitivity pneumonitis
There is subtle opacity in the centre of the secondary lobules (arrows) with
sparing of the subpleural region.

35. Subacute hypersensitivity pneumonitis
with mosaic pattern
Some secondary lobules demonstrate ground-glass opacity due to lung
infiltration, while others are more lucent due to bronchiolitis with air trapping.

36. Chronic hypersensitivity pneumonitis
The key findings in chronic hypersensitivity
pneumonitis are:
• Mosaic pattern with areas of ground-glass
attenuation and areas of low attenuation.
• Fibrosis and parenchymal distortion in a mid
zone distribution.

37. Chronic hypersensitivity pneumonitis:
Nonspecific chest film, typical HRCT-findings.
The HRCT shows a mosaic pattern.
Additionally there is septal and intralobular reticular thickening,
indicating already existing irreversible fibrosis.

38. Differential diagnosis of
Hypersensitivity Pneumonitis
• Subacute stage:
– RB-ILD: seen in smokers, upper lobe predilection,
usually associated with centrilobular emphysema.
– Alveolar proteinosis.
• Chronic stage:
– UIP: may show very similar HRCT findings.
UIP has a strong lower zone distribution.
In chronic HP fibrotic changes are typically seen
throughout the whole lung parenchyma from the
periphery towards the centre.

39. UIP with honeycombing (left) and chronic HP (right)

40. Tuberculosis
• Primary TB: Initial infection with consolidation, adenopathy and
pleural effusion.
• Secondary TB : Post-primary or reactivation TB.
This is the reactivation of the original infection.
Usually located in the apical segments of upper lobes with
cavitation
• Endobronchial spread: May occur in both primary and secondary
TB, when the infection is not contained.
• Hematogenous spread (miliary TB): May occur in both primary
and secondary TB, when the infection is not contained.

41. HRCT findings in TB
• Primary TB:
– Consolidation anywhere, lymphadenopathy and pleural
effusion. Usually regresses to calcified lung nodule and
calcified ipsilateral lymph node.
• Secondary TB:
– Consolidation in apical segments of upper lobes or
superior segments of lower lobes.
– Cavitation
• Endobronchial spread:
– Tree in bud appearance
• Miliary TB:
– 2-3 mm nodules with random distribution.

42. TB: cavitating lesion and
endobronchial spread
There is a cavitating lesion and typical tree-in-bud appearance. The
blue arrow indicates the biopsy needle.

43. Miliary TB
• This represents a haematogenous
dissemination of infection and may occur in
association with either primary or post
primary disease.
• It is characterized by uniform small nodules
with a random distribution.

44. Miliary TB
Uniform small nodules with a random distribution

45. Endobronchial spread of TB
• This can occur with primary or postprimary infection.
• In most subjects, the primary infection is localized and clinically
inapparent. However, in 5 to 10% of patients with primary TB, the
infection is poorly contained and dissemination occurs.
This is termed progressive primary tuberculosis.
• Extensive cavitation of the tuberculous pneumonia lead to endobronchial
spread of the infection.
• Rupture of necrotic lymph nodes into the bronchi can also result in
endobronchial dissemination.
• Tree-in-bud appearance is typical for active endobronchial spread of
infection. It occurs in acute tuberculosis but also in any other bacterial
infection.

46. Endobronchial spread of TB with tree-
in-bud

47. Differential diagnosis of TB
• Primary TB: Acute bacterial pneumonia
• Secondary TB: Sarcoidosis, Silicosis, Pneumoconiosis
• Endobronchial spread of TB: Bronchopneumonia,
Hypersensitivity pneumonitis
• Miliary TB: metastases of medullary thyroid ca,
chorion ca and melanoma. In both miliary TB and
metastases the nodules have a random distribution.
In miliary TB the nodules are more uniform in size.

48. LEFT: miliary TB
RIGHT: metastases

49. Chronic eosinophilic pneumonia
• Chronic eosinophilic pneumonia is an idiopathic condition
characterized by filling of the alveoli with eosinophils.
• It is associated with an increased number of eosinophils in the
peripheral blood and patients present with fever, cough,
weight loss, malaise, and shortness of breath.
The symptoms are often severe and last three months or
more.
Patients respond promptly to treatment with steroids.

50. HRCT/CT findings in Chronic
eosinophilic pneumonia
• Contrast enhanced CT in a patient with chronic
eosinophilic pneumonia.
Notice peripheral distribution of the consolidations.

51. Differential diagnosis of Chronic
eosinophilic pneumonia
• Organizing pneumonia (COP)
• Löffler syndrome (eosinophilia and vanishing
peripheral consolidations)
• Churg-Strauss syndrome (also serum
eosinophilia, asthma, systemic vasculitis
affecting multiple organs: renal insufficiency,
arthralgia and myocarditis and pericarditis)
• Pulmonary infarcts

52. Chronic eosinophilic pneumonia (left)
versus Organizing pneumonia (right)
The images show the similarities between chronic eosinophilic pneumonia and
organizing pneumonia.
Differentiation has to be made on the basis of clinical and laboratory findings.

53. Pneumocystis carinii pneumonia
• Pneumocystis carinii pneumonia (PCP) or
pneumocystis jiroveci as it is currently named, is an
opportumistic infection in immunocompromised
patients.
• PCP used to affect most HIV-infected patients at some
point during the course of their disease, but with the
new anti-viral drugs it has become less common.
• Nowadays PCP is seen more in immunosuppressed
patients, i.e. transplant recipients and patients on
chemotherapy.

54. HRCT findings in PCP
• Perihilar or diffuse ground-glass opacification.
• Sometimes thickened septal lines in association with
areas of ground-glass
• Later cysts (or pneumatoceles) in 10-35% of patients,
typically involving upper lobes
• Cysts may have bizarre shapes and thick walls
• Following therapy these lesions eventually regress,
resulting either in complete disappearance, or residual
nodules or scars
• Pneumothorax in 35% of patients with cysts

55. Immunocompromised patient with
PCP
The CT findings are diffuse ground-glass opacification.
The findings are not specific for PCP, but in this clinical setting PCP is the most likely
diagnosis.

56. ARDS
• Acute respiratory distress syndrome (ARDS) is a sudden, life-threatening
lung failure requiring mechanical ventilation.
• ARDS represents the result of increased permeability often in combination
with injury to the respiratory epithelium.
A variety of underlying conditions, from infections to major trauma, can
cause ARDS.
Primary pulmonary risk factors include aspiration, pneumonia, toxic
inhalation and pulmonary contusion.
Extrapulmonary risk factors are sepsis, pancreatitis, multiple blood
transfusions, trauma and the use of drugs such as heroin.
• Mild forms of ARDS may resolve completely, while severe forms result in
irreversible fibrosis.
Why some people develop ARDS and others do not is unknown.

57. Extra-pulmonary ARDS
• A patient who was involved in a traffic accident and within hours
developed ARDS.
The dominant pattern is ground glass opacity.
In the dependent parts of the lung there is also some consolidation, so
there is a gradient from front to back.
An important finding in extra-pulmonary ARDS is the symmetry of the
abnormalities.

58. Pulmonary ARDS
• Patient who developed ARDS as a result of pneumonia (i.e. pulmonary
ARDS).
Note the patchy distribution of lung disease and the almost complete
distortion more basal.
Patient is ventilated with PEEP (positive end expiratory pressure ) leading to
a barotrauma of the lung parenchyma: there are multiple subpleural cysts
and a bilateral pneumothorax.

59. Idiopathic interstitial pneumonias
• The idiopathic interstitial pneumonias (IIPs) comprise a
heterogeneous group of disorders.
• They represent fundamental responses of the lung to injury
and do not represent 'diseases' per se.
• Idiopathic indicates unknown cause and interstitial
pneumonia refers to involvement of the lung parenchyma by
varying combinations of fibrosis and inflammation.
• IIPs include seven entities listed in the table in order of
relative frequency.
• These diseases have specific patterns of morphologic findings
on HRCT and histology.

61. Usual Interstitial Pneumonitis (UIP)
• UIP is a histological diagnosis.
UIP has distinctive HRCT findings and is usually shown at lung biopsy,
when honeycombing is visible.
• If the UIP pattern is of unknown cause (i.e. idiopathic), the disease is
called Idiopathic pulmonary fibrosis (IPF).
IPF accounts for more than 60% of the cases of UIP.
• In the presence of a surgical biopsy showing a UIP pattern the diagnosis of
IPF requires exclusion of other known causes of UIP including drug
toxicities, environmental exposures (asbestos), and collagen vascular
diseases like RA, SLE, polyarteritis nodosa and scleroderma.
• A long list of drugs have been implicated, but this pattern is most
commonly the result of cytotoxic chemotherapeutic agents such as
bleomycin, busulfan, vincristine, methotrexate, adriamycin, and
carmustine (BCNU).

62. UIP due to IPF
• The findings on the chest film comprise volume loss and fibrotic changes in the basal
lung area.
The radiographic appearance of honeycombing comprises reticular densities caused
by the thick walls of the cysts.
Whenever you see a chest film with long standing reticulation with a lower lobe and
peripheral preference also think 'UIP'.
Chest film in a patient
with UIP demonstrating
the reticular pattern in
basal and subpleural
distribution due to
honeycombing.

63. HRCT findings in UIP
• Honeycombing consisting of multilayered thick-walled
cysts.
• Architectural distortion with traction bronchiectasis due to
fibrosis.
• Predominance in basal and subpleural region.
• Mild mediastinal lymphadenopathy

64. Nonspecific interstitial pneumonia
(NSIP)
• NSIP representing cases of idiopathic interstitial pneumonia
that cannot be classified as UIP, DIP, or OP.
• NSIP is histologically characterized by a homogeneous,
uniform pattern of cellular interstitial inflammation
associated with variable degrees of fibrosis.
• In contrast, UIP is associated with extensive fibrosis which is
temporally inhomogeneous (i.e. various lesions are of
different ages).
• NSIP ranges from type I which is a cellular pattern seen as
ground glass opacity on HRCT to type IV with a fibrotic
pattern, which may be indistinguishable from UIP.

65. • This patient had a rash and muscle
weakness.
• The predominant finding is ground
glass opacity (GGO).
There is very subtle traction
bronchiectasis, indicating that the GGO
is the result of fibrosis and therefore
irreversible.
The history of this patient is suggestive
for the diagnosis dermatomyositis.
• NSIP is by far the most common
interstitial lung disease in patients with
connective tissue disease.
NSIP

66. COP / BOOP
• Cryptogenic organizing pneumonia (COP) used to be described as
bronchiolitis obliterans with organizing pneumonia (BOOP) in an earlier
version of the classification of idiopathic interstitial pneumonias.
• It is a inflammatory process in which the healing process is characterized
by organization of the exudates rather than by resorption ('unresolved
pneumonia').
• Organizing pneumonia is mostly idiopathic and then called cryptogenic,
but is also seen in patients with pulmonary infection, drug reactions,
collagen vascular disease, Wegener's granulomatosis and after toxic-fume
inhalation.
• OP presents with a several-month history of nonproductive cough, low-
grade fever, malaise and shortness of breath.
There is a good response to corticosteroid therapy and a good prognosis.

67. HRCT findings in OP
• Bilateral peripheral consolidations, sharply
demarcated.
• Consolidations may be migratory.
• Lesions may show pleural tags or spiculae and give the
impression of volume loss and slight retraction of the
surrounding parenchyma (DD bronchogenic
carcinoma).
• Bronchial wall thickening and dilatation are seen in
most patients and are usually restricted to areas of
consolidation or ground glass opacifications.
• Additional findings are pleural thickening, small pleural
effusions and parenchymal bands.

68. A patient with the typical bilateral peripheral consolidations of OP.
After exclusion of other diseases such as lymphoma, infection, bronchoalveolar
carcinoma, the diagnosis of cryptogenic organizing pneumonia was made.

69. • A patient with rheumatoid arthritis and bilateral
peripheral consolidations as a result of organizing
pneumonia.
Patients with OP associated with collagen vascular
diseases respond less well to therapy with steroids.

70. Differential diagnosis of Organizing
Pneumonia
• Chronic eosinophilic pneumonia
• Bronchoalveolar cell carcinoma
• Aspiration pneumonia
• Pulmonary infarction
• Lymphoma

71. Chronic eosinophilic pneumonia (left)
versus Organizing pneumonia (right)
The images show the similarities between chronic eosinophilic pneumonia and
organizing pneumonia.
Differentiation has to be made on the basis of clinical and laboratory findings.

72. RB-ILD and DIP
• Respiratory bronchiolitis (RB), respiratory
bronchiolitis-associated interstitial lung
disease (RB-ILD), and desquamative interstitial
pneumonia (DIP) represent different degrees
of severity of small airway and parenchymal
reaction to cigarette smoke.

73. • All smokers have various degrees of respiratory bronchiolitis,
but it is usually asymptomatic.
• The term RB-ILD was proposed to describe the bronchocentric
(or centrilobular) lung disease in these patients and the term
DIP was used to describe the more diffuse disorder.
• Radiologically however these diseases cannot be clearly
separated because of the overlap of CT findings.

74. HRCT findings in RB-ILD
• Centrilobular nodules of ground glass opacity
with upper lobe predominance
• Bronchial wall thickening
• Secondary lobuli with decreased attenuation
(air trapping)

75. RB-ILD
The dominant feature is ground glass opacification and there are some thickened
interlobular septa (arrow).
Usually these patients will also have smoking induced centrilobular emphysema and
there is some evidence that respiratory bronchiolitis is the precursor of emphysema.

76. RIGHT: Hypersensitivity pneumonitis in non-
smoker
Note the difference in severity of ground glass opacities and the well defined areas of
air trapping in HP.
If a patient is a smoker, think RB-ILD and look for additional smoking related features.
If a patient is a non-smoker, think HP, and look at the expiratory CT scans.
Somehow smoking seems to protect against HP.
This is not a 100% specific criterion but is quite helpful for differential diagnosis.
LEFT: RB-ILD in smoker.

77. Acute interstitial pneumonia AIP
• AIP, earlier named Hamman Rich Pneumonitis
is a rare idiopathic lung disease characterized
by diffuse alveolar damage with subsequent
fibrosis.
It has a fatal outcome in many cases.
The histologic pattern as well as the HRCT
findings in AIP are indistinguishable from
acute respiratory distress syndrome (ARDS).

78. HRCT characteristics of AIP
• Diffuse or patchy consolidation, often with a
crazy paving.

79. AIP
There are areas of consolidation and extensive areas of ground-glass density
with a crazy-paving appearance.
These abnormalities developed in several days and this rapid progression of
disease combined with these imaging findings are very suggestive of the
diagnosis AIP.

80. Lymphocytic interstitial pneumonitis
LIP
• LIP is uncommon, being seen mainly in
patients with autoimmune disease,
particularly Sjögren's syndrome, and in
patients with AIDS.
Symptoms are nonspecific and often those of
the patient's underlying disease

81. HRCT findings are usually nonspecific.
A patient with Sjogren's syndrome with LIP.

82. Uncommon interstitial lung
diseases

83. Lymphangiomyomatosis
• 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).

84. Key findings in
Lymphangiomyomatosis
• 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%).

85. Lymphangiomyomatosis
A typical case of LAM with multiple evenly
spread thin walled cysts complicated by a
pneumothorax.

86. Differential diagnosis of
Lymphangiomyomatosis
• 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 Sjögren syndrome.

87. Langerhans cell histiocytosis
• 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.

88. HRCT findings in Langerhans cell
histiocytosis
• Early stage:
– Small irregular or stellate nodules in centrilobular
location.
• Late stage (more commonly seen)
– Cystic airspaces < 10 mm in diameter with walls that
range from barely perceptible to several millimetres
thick.
– Cysts have bizarre shapes, they may coalesce and than
become larger.
– Upper and mid lobe predominance.
– Recurrent pneumothorax.

89. Early stage Langerhans cell
histiocytosis with small nodules
There are no cysts visible.

90. • 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.

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

92. Radiological pathological correlation of
Langerhans cell histiocytosis in respectively
nodular stage and early and late cystic stage.

93. Differential diagnosis of Langerhans
cell histiocytosis
• 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

94. Alveolar proteinosis
• Alveolar proteinosis is a rare disease characterized by filling of
the alveolar spaces with PAS positive material due to an
abnormality in surfactant metabolism.
The diagnosis is based on the suggestive HRCT pattern (crazy
paving) and the characteristic features of BAL fluid (Broncho
Alveolar Lavage)
• Usually between 30 and 50 years old.
• Nonproductive cough, fever, and mild dyspnea.
• Prognosis has improved since the advent of treatment using
bronchoalveolar lavage.

95. Key findings in alveolar proteinosis
• Crazy paving pattern: reticular pattern
superimposed on ground glass opacification.
• Opacifications range from ground glass to
consolidation.

96. A typical case of alveolar proteinosis with extensive
thickening of interlobular and intra-lobular septa.
This is caused by the fact that the proteinacious material,
which is removed from the alveolar space by macrophages is
transported to the interstitium and thus leads to thickening
of septa.

97. Differential diagnosis of alveolar
proteinosis
• The crazy paving pattern is a rather non-specific finding.
Many other diseases may present with this finding and are
listed in the differential diagnosis.
• Non cardiogenic edema, ARDS, Acute Interstitial
Pneumonia.
• Pneumonia:
– Infection (PCP and CMV).
– OP (organizing pneumonia).
– Chronic eosinophilic pneumonia.
• Haemorrhage.
• Bronchoalveolar ca.

98. thank You