The road to HRCT evaluation of

Dr/Ahmed Bahnassy

Consultant Radiologist

Riyadh Military Hospital

Does chILD differ from adILD?1. Differences in the immune system

responces, cytokine and growth factors

2. Histologic classification differs significantly

3. Specific types presented at children not adults

4. Rarer and less stereotyped than adult ILD

5. More difficult to treat than adults.

DIP Desquamative interstitial pneumonitis

CIP Chronic pneumonitis of infancy

NSIP Non-specific interstitial pneumonitis

FB/LIP Follicular bronchiolitis /lymphoid

Interstitial Pneumonia

OP Organizing pneumonia (old BOOP)

PIG Pulmonary interstitial glycogenosis

NEHI Neuroendocrine cell hyperplasia of infancy

* UIP: Usual interstitial pneuminitis is rare in children.

Examples of common terms of chILD

Diagnostic journey of chILD?• First round investigations:

1. Imaging (HRCT)

2. Lung functions (DLCO)

3. Oxygen saturation (rest /exercise)

4. Blood tests (CBC, ESR, Immune, Serology and PCR, RAST, ACE, HIV)

5. Resp secretions cultures/PCR

6. Sweat chloride test.

7. pH study/Contrast swallow

8. ECG and ECHO

9. Ciliary Brush Biopsy

10. Urine for CMV PCR

• Second round investigations:

1. Upper GI study for ? H type fistula

2. Bronchoscopy and BAL for cytology (LCH, iron laden macrophages, PAP) and cultures

3. Videofluroscopy for aspiration evidence

4. Cardiac Cath

5. Detailed lymphocyte function tests

6. TB –Elispot test

• Third round investigations:

1. Lung biopsy

(Transbronchial,percutaneous, thoracoscopic, open lung) CT guided from affected patch and unaffected patch.

• Special stains (eg. Bompesin or PAS)

• Immunoblotting for sufactant proteins at lung biopsy

• Electron microscopy study of biopsy

• DNA for mutations in SPB, SPC and ABCA3

HRCT in children

parameters

SPL

Glossary ofTerms of HRCT

Same terminology for both adults and pediatrics

beaded septum sign

This sign consists of irregularand nodular thickening of interlobularsepta reminiscent of a row of beads

bronchiectasis

Bronchiectasis is irreversiblelocalized or diffuse bronchial dilatation,usually resulting from chronic infection,proximal airway obstruction, orcongenital bronchial abnormality

signet ring sign

This finding is composed ofa ring-shaped opacity representing a dilatedbronchus in cross section and asmaller adjacent opacity representingits pulmonary artery, with the combinationresembling a signet (or pearl) ring.

bronchiolectasis

Bronchiolectasis is definedas dilatation of bronchioles. It is causedby inflammatory airways disease (potentiallyreversible) or, more frequently,fibrosis

bronchocele

A bronchocele is bronchialdilatation due to retained secretions(mucoid impaction) usually caused byproximal obstruction, either congenital(eg, bronchial atresia) or acquired (eg,obstructing cancer)

bronchocentric

This descriptor is applied todisease that is conspicuously centeredon macroscopic bronchovascular bundlesExamples of diseases witha bronchocentric distribution includesarcoidosis , Kaposi sarcoma ,and organizing pneumonia .

broncholith

A broncholith, a calcifiedperibronchial lymph node that erodesinto an adjacent bronchus, is most oftenthe consequence of Histoplasma or tuberculousinfection.

cavity

A cavity is a gas-filled space, seen as a lucency or low-attenuation area, within pulmonary consolidation, a mass, or a nodule

crazy-paving pattern

This pattern appears asthickened interlobular septa and intralobularlines superimposed on abackground of ground-glass opacity , resembling irregularly shaped pavingstones.

cyst

A cyst is any round circumscribedspace that is surrounded by anepithelial or fibrous wall of variablethickness

consolidation

Consolidation refers to anexudate or other product of disease thatreplaces alveolar air, rendering the lungsolid (as in infective pneumonia).

ground-glass opacity

Area of hazy increased lungopacity, usually extensive, within whichmargins of pulmonary vessels may beindistinct. On CT scans, it appears ashazy increased opacity of lung, withpreservation of bronchial and vascularmargins

halo sign

The halo sign is a CT finding of ground-glass opacity surrounding a nodule or mass..It refers to severe pulmonary infection..first

described with invasive aspergillosis in leukemic patients .

reversed halo sign

The reversed halo sign is afocal rounded area of ground-glassopacity surrounded by a more or lesscomplete ring of consolidation .A rare sign, it was initially reported tobe specific for cryptogenic organizingpneumonia but was subsequentlydescribed in patients with paracoccidioidomycosis

honeycombing

Honeycombing representsdestroyed and fibrotic lung tissue containingnumerous cystic airspaces withthick fibrous walls, representing the latestage of various lung diseases, withcomplete loss of acinar architecture.The cysts range in size from a few millimetersto several centimeters in diameter, andhave variable wall thickness.

parenchymal band

It is a linear opacity, usually1–3 mm thick and up to 5 cm long thatusually extends to the visceral pleura(which is often thickened and may beretracted at the site of contact).It reflects pleuroparenchymal fibrosisand is usually associated with distortionof the lung architecture.

mycetoma

A mycetoma is a discretemass of intertwined hyphae, usually ofan Aspergillus species, matted togetherby mucus, fibrin, and cellular debris colonizinga cavity, usually from prior fibrocavitarydisease (eg, tuberculosis orsarcoidosis)

tree-in-bud pattern

The tree-in-bud pattern representscentrilobular branching structuresthat resemble a budding tree. Thepattern reflects a spectrum of endo- andperibronchiolar disorders, including mucoidimpaction, inflammation, and/or fibrosis

Nice summary From Dr/Richard Webb

Secondary Pulmonary Lobule disease patterns

Same usage for both adults and pediatrics

with different significance

The “Unit” of the lung

The secondary pulmonary lobule is a fundamental unit oflung structure, and it reproduces the lung in miniature.Airways, pulmonary arteries, veins, lymphatics, and thelung interstitium are all represented at the level of thesecondary lobule.

Anatomy of SPL

I-Perilobular pathology

Lymphangitic carcinomatosis

Sarcoidosis

Idipathic pulmonary fibrosis(rare in children)

• Typical HRCT findings in adults.

II-Centrilobular pathology.

Hypersensitivity pneumonitis

Cellular bronchiolitis

Tree-in-budin patients with a centrilobulardistribution of nodules, if the tree-inbudsign can be recognized the differentialdiagnosis is limited: Endobronchial spread of tuberculosis or nontuberculous mycobacteria Bronchopneumonia,infectious bronchiolitis Cystic fibrosis , bronchiectasis of anycause diffuse panbronchiolitisasthma or allergic bronchopulmonaryaspergillosis , constrictivebronchiolitis , follicular bronchiolitis,bronchioloalveolar carcinoma, and

intravascular metastases.

Centrilobular emphysema

Centrilobular (centriacinar) emphysemais characterized histologicallyby areas of lung destruction occurringin relation to centriacinarbronchioles and, therefore, is locatedin the center of the secondary lobuleor surrounding the centrilobular region

III-Panlobular pathology

Lobular Process

Pneumonia

Hypersensitivity pneumonitis

Headcheese sign in hypersensitivity pneumonitis

The headcheese sign is indicative of

mixed infiltrative and obstructive disease, usually associated with bronchiolitis

The most common causes of this patternare hypersensitivity pneumonitis, desquamativeinterstitial pneumonia or respiratorybronchiolitis–interstitial lung disease,sarcoidosis, and atypical infectionswith associated bronchiolitis, such as occurswith M pneumoniae.

Consider the distribution of the pathology

Same principle for both adults and pediatrics.for DD

Cranio-caudal axis

Apical

middle Basal

Transverse axis

CentralPeripheral

Or both

Antero-posterior axis

Anterior Posterior

Or both