This document provides descriptions and radiographic signs of various pulmonary conditions seen on chest x-rays and CT scans. It includes definitions of terms like secondary lobule and centrilobular emphysema. Specific pathologies covered include Langerhans cell histiocytosis, lymphangioleiomyomatosis, pulmonary fibrosis patterns, and lymphocytic interstitial pneumonia. Radiographic findings are presented for different conditions along with accompanying CT images to illustrate signs like cysts, nodules, and reticulation. Differential diagnoses are discussed based on imaging appearance.

2. Interactive Radiology
Case Presentation
Gamal Rabie Agmy, MD, FCCP
Professor of chest Diseases, Assiut university

3. Spot Diagnosis

5. S Curve of
Golden
When there is a mass
adjacent to a fissure, the
fissure takes the shape
of an "S". The proximal
convexity is due to a
mass, and the distal
concavity is due to
atelectasis. Note the
shape of the transverse
fissure.
This example represents
a RUL mass with
atelectasis

7. Pulmonary Artery
Overlay Sign
This is the same concept
as a silhouette sign. If
you can recognize the
interlobar pulmonary
artery, it means that the
mass seen is either in
front of or behind it.
This is an example of a
dissecting aneurysm.

9. Achalasia of esophagus
Inhomogeneous cardiac density:
Right half more dense than left
Density crossing midline (right black
arrow)
Right sided inlet to outlet shadow
Right para spinal line (left black
arrow)
Barium swallow below: Dilated
esophagus

11. Feeding vessel sign

17. Radiographic Signs of Pneumomediastinum
Subcutaneous emphysema
Thymic sail sign
Pneumoprecardium
Ring around the artery sign
Tubular artery sign
Double bronchial wall sign
Continuous diaphragm sign
Extrapleural sign
Air in the pulmonary ligament

24. Incomplete Border Sign
(Pregnant Lady Sign)
The incomplete border sign is
useful to depict an
extrapulmonary mass on
chest radiograph.
An extrapulmonary mass will
often have a inner well defined
border and an ill-defined outer
margin . This can be attributed
to the inner margin being
tangential to the x-ray beam
and has good inherent
contrast with the
adjacent lung. On the other
hand, the outer margin is
enface or partially enface with
the x-ray beam and merges
with the pleural or chest wall
thus the border is obscured

26. Ginkgo leaf sign
• The ginkgo leaf sign is a chest plain radiography
appearance which is seen at extensive subcutaneous
emphysema of the chest wall. Air outlines the fibers of
the pectoralis major muscle and creates a branching
pattern that resembles the branching pattern in the
veins of a ginkgo leaf.

28. Juxtaphrenic peak sign
The juxtaphrenic peak sign refers to the peaked or
tented appearance of a hemidiaphragm which can
occur in the setting of lobar collapse. It is caused by
retraction of the lower end of diaphragm at an inferior
accessory fissure (most common), major fissure
or inferior pulmonary ligament. It is commonly seen
in upper lobe collapse but may also be seen in middle
lobe collapse.

30. CT angiogram Sign
Identification of vessels within an
airless portion of lung on contrast-
enhanced CT .
The vessels are prominently seen
against a background of low-
attenuation material .
Associatedwith:
bronchoalveolar cell carcinoma
lymphoma
infectious pneumonias.

32. Fallen Lung Sign
This sign refers to the appearance
of the collapsed lung occurring
with a fractured bronchus .
The bronchial fracture results in
the lung to fall away from the
hilum, either inferiorly and laterally
in an upright patient or posteriorly,
as seen on CT in a supine patient.
DD:
Pneumothorax causes a lung to
collapse inward toward the hilum.

34. Luftsichel Sign
•German for sickle of air (luft: air sichel:
crescent)
•Paramediastinal lucency due to
interposition of lower lobe apex between
mediastinum and shrunken upper lobe
•Occurs more commonly on the left than in
the right

36. Halo Sign
CT shows nodular consolidation associated with a halo of ground-glass
opacity (GGO) in both apices resulting from invasive pulmonary
aspergillosis.
This halo represents hemorrhage.
When seen in leukemic patients, is highly suggestive of the diagnosis of
invasive pulmonary aspergillosis.

37. CT Halo Sign

39. Reverse Halo Sign
•Central ground-glass opacity surrounded
by denser consolidation of crescentic or
ring shape, at least 2 mm thick
•First described by Voloudaki in 1996
•Kim in 2003 used the term reverse halo
•Found to be relatively specific for crypto-
genic organizing pneumonia (COP)

40. Reverse Halo Sign
Seen in other conditions:
•Wegener’s granulomatosis
•lymphomatoid granulomatosis
•paracoccidiodomycosis
•neoplastic (metastasis)
•invasive aspergillosis
•lipoid pneumonia

43. Tree-in-Bud Sign
•

45. Pearl ring sign

47. steeple of Salisbury
Cathedral,
Wiltshire, England

48. Steeple sign
The steeple sign (also called wine bottle
sign) refers to tapering of the
upper trachea on a frontal chest
radiograph reminiscent of a church
steeple. The appearance is suggestive
of croup, which should be obvious
clinically. A corresponding lateral x-ray
would show narrowing of the subglottic
trachea and ballooning of the
hypopharyn

50. Cancer Breast
Larger right breast
Inverted nipple
Radiation Fibrosis of
Lung
Right lung smaller
Right hemithorax smaller
Paramediastinal fibrosis

52. Atelectasis Right Lung
Homogenous density right hemithorax
Mediastinal shift to right
Right hemithorax smaller
Right heart and diaphragmatic silhouette are not identifiable

53. Silhouette Sign
Adjacent Lobe/SegmentSilhouette
RLL/Basal segmentsRight diaphragm
RML/Medial segmentRight heart margin
RUL/Anterior segmentAscending aorta
LUL/Posterior segmentAortic knob
Lingula/Inferior segmentLeft heart margin
LLL/Superior and basal segmentsDescending aorta
LLL/Basal segmentsLeft diaphragm
Cardiac margins are clearly seen because there is contrast between the fluid
density of the heart and the adjacent air filled alveoli. Both being of fluid density,
you cannot visualize the partition of the right and left ventricle because there is no
contrast between them. If the adjacent lung is devoid of air, the clarity of the
silhouette will be lost. The silhouette sign is extremely useful in localizing lung
lesions.

55. Air Bronchogram
• In a normal chest x-ray, the tracheobronchial tree is not
visible beyond the 4th order. As the bronchial tree
branches, the cartilaginous rings become thinner, and
eventually disappear in respiratory bronchioles. The
lumen of the bronchus contains air and the surrounding
alveoli contain air. Thus, there is no contrast to visualize
the bronchi.
• The air column in the bronchi beyond the 4th order
becomes recognizable if the surrounding alveoli is filled,
providing a contrast or if the bronchi get thickened
• The term air bronchogram is used for the former state
and signifies alveolar disease.

57. Finger in Glove Sign
Visible on chest radiographs or CT
•Indicates mucoid impaction within an obstructed bronchus
•Characterized by branching tubular or fingerlike opacities

59. Flat waist Sign
This sign refers to flattening of the contours of the aortic knob and adjacent
main pulmonary artery .
It is seen in severe collapse of the left lower lobe and is caused by leftward
displacement and rotation of the heart

60. Secondary lobule
Basic anatomic unit of pulmonary
structure and function.
1-2 cm and is made up of 5-15
pulmonary acini
Supplied by a small bronchiole
(terminal bronchiole) in the
center, that is parallelled by the
centrilobular artery.
Pulmonary veins and lymphatics
run in the periphery
Two lymphatic systems:
 central network
 peripheral network

61. The terminal bronchiole in the center divides into respiratory
bronchioli with acini that contain alveoli.
Lymphatics and veins run within the interlobular septa

62. Centrilobular area in blue
perilymphatic area in yellow

63. Raoof, S. , CHEST 2006; 129:805

64. 64

65. A group of terminal bronchioles
65

66. Unit of lung (0.5-3 cm)
Irregularly polyhedral
Supplied by a group of terminal bronchioles
and accompanying pulmonary arterioles
surrounded by lymph vessels
Demarcated by “interlobular septa”
pulmonary veins
pulmonary lymphatics
connective tissue stroma

67. Accompanying pulmonary arterioles
67

68. Surrounded by lymph vessels
68

69. Pulmonary veins
69

70. Pulmonary lymphatics
70

71. 71
Connective Tissue Stroma

72. Perilymphatic distribution
Centrilobular distribution
Random distribution

73. ARE NODULES IN CONTACT
WITH PLEURA
NO
CENTRILOBULAR
YES
PERILYMPHATIC RANDOM

74. Hypersensitivity
pneumonitis.
HRCT at the level of the
upper lobes reveals an “ill-
defined centrilobular nodular
pattern” characterised by
micronodules of ground-
glass opacity that are
diffusely distributed
characteristically in the
centre of the pulmonary
lobules

75. RBILD.
HRCT at the level of the upper
lobes exhibits an “ill-defined
centrilobular nodular pattern”
characterised by micronodules of
ground-glass opacity that are
diffusely distributed
characteristically in the centre of
the pulmonary lobules. In this case
the history of smoking favours the
diagnosis of respiratory
bronchiolitis interstitial lung disease

76. Miliary TB
HRCT at the level of the upper
lobes exhibits a “miliary nodular
pattern” characterised by random
micronodules diffusely and
symmetrically distributed within the
lungs having approximately the
same size

77. Miliary metastatic disease.
HRCT at the level of the upper lobes
shows a “milary nodular pattern”
characterised by random and
perilymphatic micronodules diffusely
distributed throughout the lungs that
have a more variable size compared ...

79. Differential diagnosis of a nodular
pattern of interstitial lung disease
SHRIMP
Sarcoidosis
Histiocytosis (Langerhan cell
histiocytosis)
Hypersensitivity pneumonitis
Rheumatoid nodules
Infection (mycobacterial, fungal, viral)
Metastases, Miliary TB
Microlithiasis, alveolar
Pneumoconioses (silicosis, coal
worker's, berylliosis)

83. A 27-year-old man is referred to you for evaluation of an
abnormal chest radiograph. About 5 months ago, he consulted
a doctor because of excessive thirst. Evaluation resulted in the
diagnosis of diabetes insipidus, which responded favorably to
desmopressin administered nasally. Recently, he started to
notice shortness of breath when climbing stairs, and a chest
radiograph was obtained.
•Patient history reveals significant tobacco smoking, up to two
packs daily, for at least 14 years. The patient noticed the
shortness of breath for at least 2 years, and recently, he noted
a point of tenderness over the chest wall, lateral to the
posterior axillary line on the left.
•Oxygen saturation is 94% while breathing room air, and the
rest of his vital signs were normal. Auscultation reveals only
rare crackles without prolongation of the expiratory phase.
There is a point of tenderness over the left sixth and seventh
ribs in the posterior axillary line, and a chest CT scan is
obtained.

85. The most likely diagnosis is:
A. Metastatic tumor of unknown primary
site.
B. Sarcoidosis.
C. Langerhans cell histiocytosis.
D. Idiopathic pulmonary fibrosis.

86. The most likely diagnosis is:
A. Metastatic tumor of unknown primary
site.
B. Sarcoidosis.
C. Langerhans cell histiocytosis.
D. Idiopathic pulmonary fibrosis.

87. DECREASED
LUNG
ATTENUATION

88. Lung Cysts
Pulmonary fibrosis (Honeycombing)
Lymphangiomyomatosis
Langerhanscell histiocytosis
Lymphocytic Interstitial Pneumonia (LIP)
Differential Diagnosis

89. Rough Reticular Fine Reticular
Traction
Bronchiectasis
and
Interface
sign
Honey
combing
UIP UIP or NSIP

90. Usual Interstitial Pneumonia UIP
HRCT Findings
Reticular opacities, thickened intra- and
interlobular septa
Irregular interfaces
Honey combing and parenchymal distorsion
Ground glass opacities (never prominent)
Basal and subpleural predominance

91. Basal and subpleural distribution
UIP

92. Lymphangioleiomyomatosis
(LAM)
HRCT Morphology
Thin-walled cysts (2mm - 5cm)
Uniform in size / rarely confluent
Homogeneous distribution
Chylous pleural effusion
Lymphadenopathy
in young women

95. Lymphangioleiomyomatosis (LAM)

96. Tuberous Sclerosis (young man)

97. Langerhans Cell Histiocytosis
HRCT Findings
Small peribronchiolar nodules (1-5mm)
Thin-walled cysts (< 1cm),
Bizarre and confluent
Ground glass opacities
Late signs: irreversible / parenchymal fibrosis
Honey comb lung, septal thickening,
bronchiectasis

98. 1 year later
Peribronchiolar Nodules Cavitating nodules and cysts
Langerhans Cell Histiocytosis

99. Langerhans Cell Histiocytosis

100. Langerhans Cell Histiozytosis
Key Features
Upper lobe predominance
Combination of cysts and noduli
Characteristic stages
Increased Lung volume
Sparing of costophrenic angle
S
M
O
K
I
N
G

101. .......after cessation of smoking

102. Benign lymphoproliferative
disorder
Diffuse interstitial infiltration of
mononuclear cells
Not limited to the air ways as
in follicular Bronchiolitis
LIP
= Lymphocytic Interstitial Pneumonia

103. Sjögren: LIP

104. LIP
= Lymphocytic Interstitial Pneumonia
Rarely idiopathic
In association with:
Sjögren‟s syndrome
Immune deficiency syndromes, AIDS
Primary biliary cirrhosis
Multicentric Castlemean‟s disease

105. Sjoegren disease
Dry eye and dry mouth
Fibrosis, bronchitis and bronchiolitis
LIP
Overlap
Sarcoid, DM/PM, MXCT
SLE, RA (pleural effusion)
Up to 40 x increased risk for lymphoma (mediastinal
adenopathy) and
2 x times increased risk for neoplasma

106. Young woman Dry mouth Smoker
LAM LIP Histiocytosis

107. Wegener„s disease

108. Rheumatoid Arthritis

109. Emphysema
histopathological definition
…..permanent abnormal enlargement of
airspaces distal to the bronchioles terminales
and
…...destruction of the walls of the involved
airspaces

110. Centrilobular Emphysema

111. Panlobular Emphysema

112. CLE and PLE in one Patient

113. Fibrosis and Emphysema

114. LAMEmphysema Fibrosis

115. LCHEmphysema

116. FibrosisEmphysema

118. Emphysema
Emphysema typically presents as
areas of low attenuation without
visible walls as a result of
parenchymal destruction.

119. EMPHYSEMA
Permanent, abnormal enlargement of air
spaces distal to the terminal bronchiole
and accompanied by the destruction of
the walls of the involved air spaces.
119

120. Centrilobular emphysema
Most common type
Irreversible destruction of alveolar
walls in the centrilobular portion of the
lobule
Upper lobe predominance and
uneven distribution
Strongly associated with smoking.

121. Centrilobular (proximal or
centriacinar) emphysema
Found most commonly in the upper lobes
Manifests as multiple small areas of low attenuation without a
perceptible wall, producing a punched-out appearance.
Often the centrilobular artery is visible within the
centre of these lucencies.
121

122. 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.

123. Panlobular emphysema
Affects the whole secondary lobule
Lower lobe predominance
In alpha-1-antitrypsin deficiency, but
also seen in smokers with advanced
emphysema

124. PANLOBULAR EMPHYSEMA
Affects the entire secondary pulmonary
lobule and is more pronounced in the lower
zones
Complete destruction of the entire pulmonary
lobule.
Results in an overall decrease in lung
attenuation and a reduction in size of
pulmonary vessels
124

125. PANLOBULAR EMPHYSEMA
125

126. Panlobular emphysema

127. Paraseptal (distal acinar)
emphysema
Affects the peripheral parts of
the secondary pulmonary lobule
Produces subpleural lucencies.
127

128. Paraseptal emphysema

129. Cystic lung disease
Lung cysts are defined as radiolucent areas with a
wall thickness of less than 4mm.

130. Langerhans cell histiocytosis

131. Lymphangiomyomatosis complicated by pneumothorax

132. Bronchiectasis
Bronchiectasis is defined as localized bronchial
dilatation. (signet-ring sign)
bronchial wall thickening
lack of normal tapering with visibility of airways
in the peripheral lung
mucus retention in the broncial lumen
associated atelectasis and sometimes air
trapping

133. ABPA: glove-fingershadow dueto mucoid impaction in central
bronchiectasisin a patientwith asthma.

134. Signet-Ring Sign
A signet-ring sign represents an axial cut of a dilated bronchus
(ring) with its accompanying small artery (signet).

136. Tram Tracks

137. Bronchial dilation with lack of tapering .

138. HONEYCOMBING
Defined as - small cystic spaces with
irregularly thickened walls composed of
fibrous tissue.
Predominate in the peripheral and subpleural
lung regions
Subpleural honeycomb cysts typically occur
in several contiguous layers. D/D- paraseptal
emphysema in which subpleural cysts usually
138

139. Honeycombing
Honeycombing is defined by the presence of small cystic
spaces with irregularly thickened walls composed of
fibrous tissue.

140. Causes
Lower lobe predominance :
1. UIP or interstitial fibrosis
2. Connective tissue disorders
3. Asbestosis
4. NSIP (rare)
Upper lobe predominance :
1. End stage sarcodosis
2. Radiation
3. Hypersensitivity Pneumonitis
4. End stage ARDS
140

141. Honeycombing
HRCT
showing
subpleural
broncheolecta

142. Honeycombing and traction bronchiectasis in UIP.

143. Typical UIP with honeycombing and traction
bronchiectasis in a patient with idiopathic
pulmonary fibrosis (IPF)

144. Mosiac pattern

145. Where is the pathology ???????
in the areas with increased density
meaning there is ground glass
in the areas with decreased density
meaning there is air trapping

146. Pathology in black areas
Airtrapping: Airway
Disease
Bronchiolitis obliterans (constrictive bronchiolitis)
idiopathic, connective tissue diseases, drug reaction,
after transplantation, after infection
Hypersensitivity pneumonitis
granulomatous inflammation of bronchiolar wall
Sarcoidosis
granulomatous inflammation of bronchiolar wall
Asthma / Bronchiectasis / Airway diseases

147. Airway Disease
what you see……
In inspiration
sharply demarcated areas of seemingly increased
density (normal) and decreased density
demarcation by interlobular septa
In expiration
„black‟ areas remain in volume and density
„white‟ areas decrease in volume and increase in
density
INCREASE IN CONTRAST
DIFFERENCES
AIRTRAPPING

148. Bronchiolitis
obliterans

149. Early Sarcoidosis

150. Chronic
EAA

151. Hypersensitivity pneumonitis
Extr. Allerg. Alveolitis (EAA) HRCT
Morphology
chronic: fibrosis
Intra- / interlobular septal thickening
Irregular interfaces
Traction bronchiectasis
acute - subacute
acinar (centrilobular) unsharp densities
ground glass (patchy - diffuse)

154. Pathology in white Areas
Alveolitis / Pneumonitis
Ground glass
desquamative intertitial pneumoinia (DIP)
nonspecific interstitial pneumonia (NSIP)
organizing pneumonia
In expiration
both areas (white and black) decrease in
volume and increase in density
DECREASE IN CONTRAST
DIFFERENCES

155. DI
P

156. Cellular
NSIP

157. Mosaic Perfusion
Chronic pulmonary embolism
LOOK FOR
Pulmonary hypertension
idiopathic, cardiac disease, pulmonary
disease

158. CTEPH =
Chronic thrombembolic
pulmonary hypertension

159. Hydrostatic pulmonary
oedema
“septal pattern” characterised by
thickened smoothly interlobular
septae in the right parahilar area.
Right pleural effusion is also seen

161. Lymphangitic carcinomatosis.
HRCT of the right lung shows a
“septal pattern” characterised by
diffuse nodular thickening of the
interlobular septae and the right
major fissure