Reticular pattern

2. Reticular Pattern
Gamal Rabie Agmy, MD, FCCP
Professor of chest Diseases,
Assiut university

3. Reticular Pattern
A reticular pattern results from the summation
or superimposition of irregular linear opacities.

The term reticular is defined as meshed, or in
the form of a network. Reticular opacities can be
described as fine, medium, or coarse, as the
width of the opacities increases.

A classic reticular pattern is seen with
pulmonary fibrosis, in which multiple curvilinear
opacities form small cystic spaces along the
pleural margins and lung bases (honeycomb
lung)

4. HRCT of the lung
Reticular pattern – definition
Glossary of Terms for Thoracic Imaging – Radiology 2008; 246:697

5. HRCT of the lung
thickening of the interstitial fiber network by
Reticular pattern – significance
fluid
fibrous tissue
infiltration by cells or other material
pulm. edema
lymphangitic carcin.
veno-occlusive dis.
alveolar proteinosis
IPF
collagen vascular dis.
drug-related fibrosis
amyloidosis
Predominant pattern Associated / occasional
finding
sarcoidosis
pneumoconiosis
pulm. hemorrhage
asbestosis

6. HRCT of the lung
Reticular pattern – HRCT
numerous, clearly visible interlobular septa
outlining lobules of characteristic size and shape
interlobular septal thickening
very fine network of lines within visible lobules
intralobular interstitial thickening
several layers of air-filled cysts, 3-10 mm in diameter,
with thick walls (1-3 mm)
honeycombing

7. Reticular pattern
Interlobular septal thickening – dd
smooth
thickening
pulm. edema
pulm. hemorrhage
lymphangitic carc.
lymphoma
nodular
thickening
lymphangitic carc.
sarcoidosis
amyloidosis
irregular
thickening
fibrosis

8. Reticular pattern
Interlobular septal thickening – pulmonary edema
smooth septal thickening, isolated or in combination
with ground-glass opacity
peribronchovascular and subpleural interstitial th.
perihilar and gravitational distribution, bilateral
findings of CHF

9. Reticular pattern
Interlobular septal th. – lymphangitic carcinomatosis
tumor filling of pulmonary vessels and lymphatics
direct tumor infiltration of the interstitium
vascular and lymphatic distension distally to tumor
emboli or obstruction
breast ca.
lung ca.
stomach ca.
pancreas ca.
Secondary to:
prostate ca.
adenoca. of
unknown origin

10. Reticular pattern
Interlobular septal th. – lymphangitic carcinomatosis
smooth or nodular septal thickening
smooth or nodular thickening of peribronchovascular
interstitium and fissures
thickening of the intralobular axial interstitium
focal or asymmetric distribution

11. Reticular pattern
Interlobular septal thickening – sarcoidosis
reticulation is not a predominat finding
distorsion of the lung architecture and secondary
lobule anatomy is common, especially when septal
thickening is present
upper lobe predominance

12. Reticulation or not reticulation ……
“crazy paving”

13. Reticulation or not reticulation ……
alveolar proteinosis

14. Reticular pattern
Interlobular septal thickening – “crazy paving”
scattered or diffuse ground-glass attenuation with
superimposed interlobular septal thickening and
intralobular lines
described in a variety of infectious, neoplastic,
idiopathic, inhalation, and sanguineous disorders of
the lung
Rossi SE – Radiographics 2003; 23:1509

15. Reticular pattern
Honeycombing – significance
air-containing cystic spaces having thick,
fibrous walls lined by bronchiolar
epithelium


fibrosis is present
UIP is likely the histologic pattern
IPF is very likely, in the absence of a
known disease

16. Reticular pattern
Honeycombing – differential diagnosis
basal
distribution
middle/upper
distribution
chronic HP
sarcoidosis
IPF
collagen vasc. dis.
asbestosis
drugs

17. honeycombing /
intralobular reticulation
basal and peripheral
distribution
typical HRCT findings
sens. 77%
spec. 72%
PPV 85%
PPV 96%*
Swigris JJ – Chest 2005; 127:275
lung biopsy in patients who
do not show typical features
Reticular pattern
Honeycombing – idiopathic pulmonary fibrosis
* confident diagnosis

18. Reticular pattern
Honeycombing – collagen vascular diseases
rheumatoid arthritis and scleroderma
almost indistinguishable from UIP due to IPF
associated findings, typical of the disease, may help in the
differential diagnosis

19. Reticular pattern
Honeycombing – drug reaction
findings of fibrosis, similar to those seen in IPF
peripheral and subpleural predominance
highest incidence with cytotoxic agents
temporal relationship between drug administration and
development of pulmonary abnormalities
Honeycombing – chronic hypersensitivity pneum.
possible association with poorly
defined nodules, mosaic attenuation
or air-trapping
upper and middle zone
predominance

20. Reticular pattern
Intralobular interstitial thickening – significance
thickening of the pulmonary interstitium
at a sublobular level
isolated (fibrosis)
in association with septal thickening
or the “crazy paving” pattern
very fine linear structures below the
resolution of HRCT (gg appearance)


21. Reticular pattern
adapted from: Webb RW – HRCT of the lung, III ed; 2001
interlobular septal thickening
irregular, lung
distorsion
nodular smooth
•fibrosis
(sarcoidosis,
asbestosis)
•pulm. edema
•linf. carc.
•hemorrhage
•sarcoidosis
•linf. carc.

22. Reticular pattern
adapted from: Webb RW – HRCT of the lung, III ed; 2001
honeycombing
•IPF (60%)
•collagen vascular dis.
•drug reaction
•asbestosis (uncommon)
subpleural, posterior
LL predominance
•sarcoidosis
•chronic HP
•radiation
other distribution
(UL; parahilar)

23. Reticular pattern
adapted from: Webb RW – HRCT of the lung, III ed; 2001
intralobular interstitial thickening
& septal thickening & GGO
isolated
NSIP
findings of fibrosis
honeycombing
differential dx

24. Reticular pattern
In the reticular pattern there are too many lines, either as
a result of thickening of the interlobular septa or as a
result of fibrosis as in honeycombing.

25. Focal septal thickening in lymphangitic carcinomatosis

26. Septal thickening and ground-glass opacity
with a gravitational distribution in a patient
with cardiogenic pulmonary edema.

27. Tree-in-bud
Centrilobular nodules m/b further characterized by presence or
absence of ‘‘tree-in-bud.’’

Tree-in-bud -- Impaction of centrilobular bronchus with mucous,
pus, or fluid, resulting in dilation of the bronchus, with associated
peribronchiolar inflammation .

 Dilated, impacted bronchi produce Y- or V-shaped structures

This finding is almost always seen with pulmonary infections.

27

28. Tree-in-bud
Tree-in-bud describes the appearance of an irregular and often nodular
branching structure, most easily identified in the lung periphery.

29. Typical Tree-in-bud appearance in a patient with active TB.

30. Attenuation pattern
High Attenuation pattern

GROUND GLASS
CONSOLIDATION

Low Attenuation pattern

Emphysema
Lung cysts (LAM, LIP, Langerhans cell histiocytosis)
Bronchiectasis
Honeycombing

31. Dark bronchus sign in ground glass opacity.
Complete obscuration of vessels in consolidation.

32. Ground-glass opacity

33. Broncho-alveolar cell carcinoma with ground-glass
opacity and consolidation

34. Consolidation

35. Two patients with chronic consolidations as a result of COP
(cryptogenic organizing pneumonia)

36. Mosaic attenuation
The term 'mosaic attenuation' is used to describe density
differences between affected and non -affected lung areas.

37. Mosaic attenuation

Lung density and attenuation depends
partially on amount of blood in lung tissue.

May be due to
vascular obstruction,
abnormal ventilation or
airway disease
37

39. Mosaic pattern in a patient with hypersensitivity pneumonitis

40. Mosaic pattern in a patient with chronic thromboemboli

41. Crazy Paving Pattern
Crazy Paving is a combination of ground glass opacity with
superimposed septal thickening

Crazy Paving can be seen in:
Alveolar proteinosis
Sarcoid
NSIP
Organizing pneumonia (COP/BOOP)
Infection (PCP, viral, Mycoplasma, bacterial)
Neoplasm (Bronchoalveolarca (BAC)
Pulmonary hemorrhage
Edema (heart failure, ARDS, AIP)

42. CRAZY PAVING PATTERN
It is scattered or diffuse ground-glass
attenuation with superimposed interlobular
septal thickening and intralobular lines.
Causes:

42

43. Crazy Paving in a patient with Alveolar proteinosis.

44. Crazy Paving
Combination of ground glass
opacity and septal thickening :
Alveolar proteinosis.

45. Combination of
ground glass opacity
and septal thickening
: Alveolar proteinosis 45

46. Head cheese sign
It refers to mixed
densities which includes
# consolidation
# ground glass
opacities
# normal lung
# Mosaic perfusion

•Signifies mixed
infiltrative and
obstructive disease

47. Head cheese sign
Common cause are :

1.Hypersensitive pneumonitis

2.Sarcoidosis

3.DIP
47

48. Headcheese sign
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
perfusion (large arrows).

49. Low Attenuation pattern
Emphysema

Lung cysts (LAM, LIP, Langerhans cell
histiocytosis)

Bronchiectasis

Honeycombing

50. Differential diagnosis of
interstitial lung diseases
Reticular pattern

Nodular pattern

High Attenuation pattern

Low Attenuation pattern

52. Lymphangitic
carcinomatosis:
irregular septal
thickening, usually
focal or unilateral
50% adenopathy',
known carcinoma.

54. Cardiogenic
pulmonary edema:
incidental finding in
HRCT, smooth septal
thickening with basal
predominance (Kerley
B lines), ground-glass
opacity with a
gravitational and
perihilar distribution,
(peribronchial cuffing)

55. Cardiogenic
pulmonary edema

56. Lymphangitic
carcinomatosis

57. Lymphangitic
carcinomatosis with
hilar adenopathy

58. Nodular pattern

1.Hypersensitivity pneumonitis:
2.Miliary TB: random nodules
3.Sarcoidosis
4.Hypersensitivity pneumonitis

59. Nodular pattern
Hypersensitivity pneumonitis Miliary TB
Sarcoidosis Hypersensitivity pneumonitis

60. Low Attenuation pattern
Lymphangiomyomatosis (LAM) LCH
Honeycombing Centrilobular emphysema

61. Low Attenuation pattern (2)
Centrilobular emphysema:
Langerhans cell histiocytosis (LCH)
Honeycombing.
Lymphangiomyomatosis (LAM)