Reticular Pattern

Gamal Rabie Agmy, MD, FCCP

Professor of chest Diseases,

Assiut university

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)

HRCT of the lung

Reticular pattern – definition

Glossary of Terms for Thoracic Imaging – Radiology 2008; 246:697

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

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

Reticular pattern

Interlobular septal thickening – dd

smooth thickening

pulm. edema pulm. hemorrhage lymphangitic carc. lymphoma

nodular thickening

lymphangitic carc. sarcoidosis amyloidosis

irregular thickening

fibrosis

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

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

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

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

Reticulation or not reticulation ……

“crazy paving”

Reticulation or not reticulation ……

alveolar proteinosis

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

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

Reticular pattern

Honeycombing – differential diagnosis

basal distribution

middle/upper distribution

chronic HP sarcoidosis

IPF collagen vasc. dis. asbestosis drugs

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

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

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

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)

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.

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)

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

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.

Focal septal thickening in lymphangitic carcinomatosis

Septal thickening and ground-glass opacity

with a gravitational distribution in a patient

with cardiogenic pulmonary edema.

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

Tree-in-bud

Tree-in-bud describes the appearance of an irregular and often nodular

branching structure, most easily identified in the lung periphery.

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

Attenuation pattern

High Attenuation pattern

GROUND GLASS

CONSOLIDATION

Low Attenuation pattern

Emphysema

Lung cysts (LAM, LIP, Langerhans cell histiocytosis)

Bronchiectasis

Honeycombing

Dark bronchus sign in ground glass opacity.

Complete obscuration of vessels in consolidation.

Ground-glass opacity

Broncho-alveolar cell carcinoma with ground-glass

opacity and consolidation

Consolidation

Two patients with chronic consolidations as a result of COP

(cryptogenic organizing pneumonia)

Mosaic attenuation

The term 'mosaic attenuation' is used to describe density

differences between affected and non-affected lung areas.

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

Mosaic pattern in a patient with hypersensitivity pneumonitis

Mosaic pattern in a patient with chronic thromboemboli

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)

CRAZY PAVING PATTERN

It is scattered or diffuse ground-glass

attenuation with superimposed interlobular

septal thickening and intralobular lines.

Causes:

42

Crazy Paving in a patient with Alveolar proteinosis.

Crazy Paving

Combination of ground glass

opacity and septal thickening :

Alveolar proteinosis.

Combination of

ground glass opacity

and septal thickening

: Alveolar proteinosis 45

Head cheese sign

It refers to mixed

densities which includes

# consolidation

# ground glass

opacities

# normal lung

# Mosaic perfusion

• Signifies mixed

infiltrative and

obstructive disease

Head cheese sign

Common cause are :

1. Hypersensitive pneumonitis

2. Sarcoidosis

3. DIP

47

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).

Low Attenuation pattern

Emphysema

Lung cysts (LAM, LIP, Langerhans cell

histiocytosis)

Bronchiectasis

Honeycombing

Differential diagnosis of

interstitial lung diseases

Reticular pattern

Nodular pattern

High Attenuation pattern

Low Attenuation pattern

Lymphangitic

carcinomatosis:

irregular septal

thickening, usually

focal or unilateral

50% adenopathy',

known carcinoma.

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)

Cardiogenic

pulmonary edema

Lymphangitic

carcinomatosis

Lymphangitic

carcinomatosis with

hilar adenopathy

Nodular pattern

1.Hypersensitivity pneumonitis:

2.Miliary TB: random nodules

3.Sarcoidosis

4.Hypersensitivity pneumonitis

Nodular pattern

Hypersensitivity pneumonitis Miliary TB

Sarcoidosis Hypersensitivity pneumonitis

Low Attenuation pattern

Lymphangiomyomatosis (LAM) LCH

Honeycombing Centrilobular emphysema

Low Attenuation pattern (2)

Centrilobular emphysema: Langerhans cell histiocytosis (LCH)

Honeycombing. Lymphangiomyomatosis (LAM)