INTERSTITIAL LUNG DISEASES

NAVDEEP SINGH

HRCT - TECHNIQUE

Narrow slice thickness (1 mm) at 10 mm intervals. Image reconstruction with high spatial resolution. Generally end inspiration views are taken. One can also take expiration , prone views when

required. A window width of 1300 , window level of -6oo HU

is set. No IV injection of contrast is used.

COMMON PATTERNS RETICULAR - caused by thickened interlobular or

intralobular septa.- infiltration by fibrosis, abnormal cells, or

fluid.- Interlobular septal thickening is usually

described as smooth OR irregular.- manifests as a fine reticular pattern on HRCT.- Late stage – honeycombing, characterized

by cystic airspaces surrounded by irregular walls.

Honeycombing

HRCT showing subpleural broncheolectasis

Nodular interstitial thickening in sarcoidosis

Nodular - feature of both interstitial and airspace

disease.- Perilymphatic nodules within the lung

interstitium, especially those related to the lymphatic vessels, are seen in the interlobular septa, subpleural and peribronchovascular regions.

- Centriacinar nodules- Random

Centriacinar nodules

Centriacinar nodules in a patient with subacute hypersensitivity pneumonitis

PERILYMPHATIC NODULES

Perilymphatic and Random distribution of

nodules , seen in sarcoidosis.

Ground glass - is defined as a generalized increase in

opacity that does not obscure pulmonary vessels.

- include partial filling of the airspaces, considerable thickening of the interstitium, or a combination of the two.

Groundglass appearence

-Opacity without obscuration of vessels.- Resolving pulmonary haemorrhage

Mosaic - refers to regional attenuation differences

demonstrated on HRCT. - depends on the amount of blood,

parenchymal tissue and air in that area.- small airways disease, occlusive vascular

disease and infiltrative lung disease.

Mosaic pattern

Mosaic pattern due to air trapping/altered perfusion

ATS –ERS classification of IIPs (idiopathic interstitial pneumonia)

This is a clinical , radiological , pathological classification.

1.UIP 2.NSIP 3.COP 4.RB-ILD 5.DIP 6.LIP 7.AIP

UIP/IPF HISTOLOGIC PATTERN

CHARACTERISTICS Temporal inhomogeneity Dense fibrosis Fibroblastic foci Patchy lung involvement Subpleural and basal predominance DIFFERENTIAL DIAGNOSIS Idiopathic (IPF) Collagen-vascular disease Asbestosis Drug toxicity Radiation Chronic hyersensitivity pneumonitis Familial pulmonary fibrosis

CRITERIA FOR A DIAGNOSIS OF IDIOPATHIC PULMONARY FIBROSIS

MAJOR CRITERIA

– Exclusion of known causes such as exposure, drugs etc - Abnormal pulmonary function tests with restrictive pattern - HRCT findings - Transbronchial lung biopsy or BAL

MINOR CRITERIA

- Age > 50 years - Insidious onset of dyspnea on exertion - Duration of illness >3 months - Bibasilar inspiratory crackles

The number of fibroblastic foci on lung biopsy is an important predictor of survival.

Classic chest radiographic features include bilateral asymmetric peripheral reticular opacities most profuse at the lung bases associated with lung volume loss.

As the disease progresses, it often appears to ‘creep’ around the periphery of the lung to involve the anterior aspects of the upper lobes.

The rapid development of a diffuse increase in the attenuation of lung parenchyma in patients with IPF should raise the possibility of an opportunistic infection

Usual interstitial pneumonia. HRCT abnormalities predominate in the posterior, subpleural regions of the lower lobes and comprise honeycombing and traction bronchiectasis within the abnormal lung.

UIP PATTERN

Coarse reticular opacities, subpleural honeycombing and traction bronchiectasis

Usual interstitial pneumonia. HRCT performed (A) before and (B) after clinical deterioration in a patient with biopsy proven usual interstitial pneumonia. HRCT obtained during the accelerated phase of the disease demonstrates a generalized increase in lung attenuation and progression of both the reticular and honeycomb patterns.

CHAPTER 19 - High-Resolution Computed Tomography of Interstitial and Occupational ...Page 7 of 55

Non-specific interstitial pneumonia

NSIP is characterized by varying degrees of interstitial inflammation and fibrosis without the specific features that allow a diagnosis of UIP or DIP.

NSIP may have significant fibrosis, it is usually of uniform temporality (in comparison to UIP).

On HRCT, NSIP is characterized by a predominant pattern of ground-glass opacification in a predominantly basal and subpleural distribution with or without associated distortion of airways.

A reticular pattern is common but honeycombing is sparse or absent.

NSIP may be distinguished from UIP on CT by a more prominent component of ground-glass attenuation and a finer reticular pattern in the absence of honeycombing.

Non-specific interstitial pneumonia. The predominant abnormality is patchy, bilateral ground-glass opacification, mild reticulation and traction bronchiectasis. There is no frank honeycombing destruction.

Cryptogenic organizing pneumonia

is identifiable in a variety of different contexts, including infection, malignancy, drug-related lung injury.

On a chest radiograph the most frequent feature of COP is patchy, often subpleural and basal, areas of consolidation with preservation of lung volumes.

The areas of airspace consolidation have a propensity to progress and change location over time.

On HRCT, consolidation corresponding to areas of organizing pneumonia is the cardinal feature found more frequently in the lower zones, with either a subpleural or a peribronchial distribution.

Ground-glass opacification, subpleural linear opacities and a distinctive perilobular pattern.

The histopathological appearance of organizing pneumonia is a uniform temporal appearance of mild interstitial chronic inflammation associated with an intraluminal organizing fibrosis in distal airspaces.

Cryptogenic organizing pneumonia. HRCT through the upper lobes demonstrates areas of consolidation in a subpleural and peribronchial distribution in association with areas of ground-glass opacification (left upper lobe).

Respiratory bronchiolitis–interstitial lung disease and desquamative interstitial

pneumonia

strong association with cigarette smoking insiduous onset of dyspnoea and cough. chest radiograph is relatively insensitive On HRCT,in RB–ILD = areas of patchy

ground-glass opacification (resulting from macrophage accumulation within alveolar spaces and alveolar ducts)

and poorly defined low attenuation centrilobular nodules .

In addition, upper lobe centrilobular emphysema.

DIP = Ground-glass opacification is typically lower zone, peripheral and may be patchy.

Some features of interstitial fibrosis may be seen.

Smoking cessation is an important part of the management.

global term smoking related-interstitial lung disease (SR-ILD) has been proposed

Respiratory bronchiolitis–interstitial lung disease. HRCT shows (A) subtle areas of ground-glass opacification and (B) ill-defined centrilobular nodules

Several areas of non-specific ground-glass opacification in the right middle lobe and both lower lobes

Acute interstitial pneumonia

idiopathic form of the ARDS histological pattern seen in AIP is that of

diffuse alveolar damage (DAD), which is also found in infection, connective tissue disease, drug toxicity, toxic inhalation, uraemia and sepsis.

DAD has an acute exudative phase and a subsequent organizing and fibrotic phase.

diffuse involvement with temporal homogeneity.

chest radiograph shows bilateral patchy airspace opacification.

HRCT demonstrates a combination of ground-glass opacification, consolidation, bronchial dilatation and architectural distortion.

Lymphoid interstitial pneumonia

characterized by a widespread interstitial lymphoid infiltrate of the lung.

association with autoimmune diseases, most often Sjögren's syndrome. Other diseases include dysproteinaemias, autologous bone marrow transplantation and viral, mycobacterial and human immunodeficiency virus (HIV) infections, Intrathoracic Castleman's disease.

Female > male

progressive cough and dyspnoea usually predominate.

HRCT findings are nodules of varying sizes, areas of ground-glass opacification, thickened bronchovascular bundles, interlobular septal thickening and thin-walled cysts (1–30 mm).

The cysts in LIP are usually discrete, are not found in clusters and are found deep within the lung parenchyma.

Lymphocytic interstitial pneumonitis. There is a background of ground-glass opacification and a few thin-walled cystic airspaces.

     

LANGERHANS CELL HISTIOCYTOSIS

is a granulomatous disorder characterized histologically by the presence of large histiocytes containing rod- or racket-shaped organelles.

male-to-female ratio is about 4:1, and the vast majority of adult patients are cigarette smokers.

present with dyspnoea, cough, constitutional symptoms or a spontaneous pneumothorax.

Pulmonary involvement is widespread, bilateral and usually symmetrical.

Typical appearances are of reticulonodular shadowing in the mid and upper zones of the lungs that are of normal or increased volume.

The nodules vary in size from micronodular to approximately 1 cm in diameter and, although histopathological examination will often demonstrate cavitation.

On HRCT are nodules (ranges from a few mm to 2 cm), several of which show cavitation (this feature often clinches the diagnosis) and have bizarre shapes.

Langerhans cell histiocytosis. (A) Shows the characteristic combination of thin-walled cysts and poorly defined nodules, some of which are just beginning to cavitate. (B) Image from a patient with more advanced disease. There are numerous irregularly-shaped cysts bilaterally and a pneumothorax on the right.

LYMPHANGIOLEIOMYOMATOSIS

characterized histologically by two key features: cysts and proliferation of atypical smooth muscle cells (LAM cells) of the pulmonary interstitium, particularly in the bronchioles, pulmonary vessels and lymphatics.

LAM is a rare disease seen almost exclusively in women.

approximately 1% of patients with tuberous sclerosis.

pattern of generalized, symmetrical, reticular, or reticulonodular opacities with normal or increased lung volumes.

Pleural effusions occur in 10–40% of patients and pneumothoraces in approximately 50% of cases. The effusions are chylous and result from involvement of the thoracic duct by the leiomyomatous tissue.

characterized by numerous thin-walled cysts randomly distributed throughout the lungs with no zonal predilection.

Imaging features that help distinguish LAM from LCH include a more diffuse distribution of cysts typically with no sparing of the bases, more regularly shaped cysts and normal intervening lung parenchyma.

Lymphangioleiomyomatosis. (A) There is a profusion of thin-walled cystic airspaces scattered evenly throughout the lungs. The cysts are relatively uniform in size. (B) In a more advanced case of LAM, note the small left-sided pleural effusion.

Case 1 65 year old male with progressive

breathlessness. Chest Xray shows prominent

bronchovascular markings

HRCT shows-Honeycombing-Traction bronchiectasis-Septal thickening

Diagnosis – UIP pattern

Case 2

50 year old male with history of dry cough , malaise , low grade fever.

Chest Xray- shows persistent pneumonitis patches.

HRCT shows bilateral peripheral consolidation and

groundglass opacities suggesting the ….

diagnosis of COP.

CASE 3

North Indian worker brought by his employer. He complains of recent breathlessness on coming to work.

Normal chest Xray.

HRCT shows ground glass opacities were seen in both lungs.

Referring doctor informed me that patient was working in a poultry farm . So

, possible Subacute hypersensitivity pneumonitis.