ILO CLASSIFICATION OF OCCUPATIONAL LUNG DISEASES DR KHANYAKUDE S MASHAO MBCHB,MMED RAD(D),DOH,PGD(BUSINESS MANAGEMENT)

ETIOLOGY AND PATHOPHYSIOLOGY OF SILICOSIS Silicosis and CWP are occupational lung diseases caused by continued exposure to excessive respiratory Silica and Coal dust. Chronic inflammation that involves phygocytosis of inhaled dust by alveolar and tissue macrophages Free particles not ingested by macrophages enters perivascular lymphatic channels The lymphatic channels drain into mediastinal and hilar lymph nodes

Occupational exposure Free crystalline silica (quartz) or silicon dioxide from Mining of coal, graphite, iron Tin, Uranium, Gold Silver, Copper Also, sand blasters Iron and steel foundry workers Ceramic workers Tunneling

CLINICAL PRESENTATION OF SILICOSIS Three main clinical presentation namely Acute Silicosis , Accelerated silicosis and classic Silicosis. Acute Silicosis An acute progressive form of silicosis that often result in death. Can develop within a few weeks to months of exposure to high levels of silica .(e g sand blasting) Workers present with progressive dyspneoa, cough, weight loss, cyanosis and respiratory failure. The lungs show ground glass appearance similar to pulmonary edema The illness is sometimes complicated by superimposed mycobacterial infections

CLINICAL PRESENTATION CONT Accelerated Silicosis Symptoms of breathlessness within a year of exposure Rate of progression is faster. X-rays changes occur 5-10 years after exposure Radiological features are similar to classic silicosis Classic Silicosis Requires 10-20 years exposure before x-ray appearance o Radiographs frequently overestimate degree of symptoms early o Silicosis has a progressive nature despite cessation of dust exposure.

Radiological features of simple silicosis Multiple small rounded opacities 1-10 mm in size Usually starts in upper lobes Mostly in apical and posterior regions of upper lobes and apical portion of lower lobes May have ground-glass appearance May occasionally calcify centrally (20%) Lymph node enlargement common Eggshell calcification of hilar nodes (5%) Large opacities are conglomerations of small opacities

CT FEATURES OF SIMPLE SILICOSIS Multiple small nodules that are upper lobe predominant and accompanied by calcifications hilar and mediastinal lymphadenopathy: may precede the appearance of parenchymal nodular lesions calcification of lymph nodes common and typically occurs at the periphery of the node this eggshell calcification pattern is highly suggestive of silicosis

SIMPLE SILICOSIS

Complicated Silicosis(progressive massive fibrosis PMF) Massive fibrosis and conglomerate nodule formation in upper lobes with scarring and retraction of hila upwards. Conglomerate nodules are >1 cm in size Usually in mid-zone or periphery of upper lobes Compensatory emphysema occurs in lower lung fields Nodules tend to disappear from rest of lung when PMF develops Progressive Massive Fibrosis (PMF) may cavitate from tuberculosis or ischemic necrosis

COMPLICATED SILICOSIS commonly in the middle lung zone or peripheral one-third of the lung gradually migrating toward the hilum, leaving emphysematous lung tissue between the fibrotic tissue and the pleural surface. The masses can be sausage shaped. CT features are focal soft-tissue masses, often with an irregular or ill-defined margins and calcifications, surrounded by areas of emphysematous change.

COMPLICATIONS OF SILICOSIS Predisposes to TB Exhibits “limited” evidence for carcinogenesis in humans

ASBESTOS REALATED DISEASE Asbestos related disease, in particular affecting the lung, comprise of a broad spectrum of entities related to the inhalational exposure to asbestos fibres. They can be divided into benign and malignant changes

BENIGN ASBESTOS RELATED PLEURAL DISEASE All patients with asbestos-related pleural disease have, by definition, some pleural involvement Pleural involvement without parenchymal disease is common Benign pleural effusion Effusion alone may occur early in the disease (first 20 years) in about 3% of cases Exudative, occasionally bloody, one-sided or bilateral.

BENIGN ASBESTOS RELATED PLEURAL DISEASE Pleural plaque Parietal pleural plaques in the mid lung are the most common asbestos-related disorder and are usually bilateral They occur most often in the 6th-9th interspaces usually sparing the apices and lung bases and involve the parietal pleura Diffuse pleural thickening Less common than pleural plaques Diffuse pleural thickening involves diaphragmatic pleura, blunting of costophrenic sulci and lateral pleural thickening

BENIGN ASBESTOS RELATED PLEURAL DISEASE Pleural calcification Pleural calcification occurs in about 50% with asbestos-related disease, especially along the diaphragmatic pleura Calcified pleural plaques seen en face have a characteristic rolled edge along their margins, denser than in the central portion of the plaque The appearance of the entire plaque has been likened to a holly leaf Later manifestation of pleural disease, calcification may occur in plaque or diffuse pleural thickening (less often)

ASBESTOSIS Asbestosis refers to later development of diffuse interstitial fibrosis secondary to asbestos fibre inhalation and should not be confused with other asbestos related diseases. Epidemiology Asbestosis typically occurs 10-15 years following the commencement of exposure to asbestos and is dose related . Heavy asbestos exposure is predominantly encountered among men, as most exposures are occupational in the setting of construction, mining or ship/automotive industries.

ASBESTOSIS Clinical presentation Clinical presentation is insidious and nonspecific with shortness of breath prompting imaging. Alternatively, the presence of asbestosis may become evident when a patient presents with other asbestos related diseases. Radiographic features Plain radiograph Chest radiograph show irregular opacities with a fine reticular pattern starting in the lung bases. Opacities are small and irregularly shaped Cardiac silhouette may become shaggy Additional evidence of asbestos exposure such as calcified or noncalcified pleural plaques may be evident.

ASBESTOSIS CT Appearances of asbestosis vary with the duration and severity of the condition. Early manifestations are largely confined to the peripheral region of the lower zones and are subtle. They include: centrilobular dot-like opacities: peribronchial fibrosis intralobular linear opacities: reticulation subpleural lines (often curvilinear) These changes may be similar in appearance to dependent atelectasis, especially when located posteriorly, and thus supine and prone scans are recommended .

ASBESTOSIS As the fibrosis progresses, a number of more definite findings are seen, which continue to be particularly sub-pleural and lower lung zone in distribution. They include: parenchymal bands traction bronchiectasis honeycomb fibrosis

ROUNDED ATELECTASIS Round atelectasis, also known as folded lung or Blesovsky syndrome, is an unusual type of lung atelectasis where there is infolding of a redundant pleura. The way the lung collapses can at times give a false mass-like appearance Almost always seen adjacent to a pleural surface There is associated adjacent pleural thickening comet tail sign : produced by the pulling of bronchovascular bundles giving the shape of a comet tail crow feet sign

MALIGNANT ASBESTOS RELATED DISEASES bronchogenic carcinoma: 5x increased risk in Asbestos exposed mesothelioma: less common than bronchogenic carcinoma but has a higher prevalence of asbestos exposure pleural mesothelioma extra pleural (e.g. peritoneal) mesothelioma

MESOTHELIOMA Carcinogenic potential: crocidolite > amosite > chrysotile > actinolite, anthophyllite, tremolite Occupational exposure of asbestos found in only 40-80% of all cases 5-10% of asbestos workers will develop mesothelioma (risk factor of 30X compared with general population) No relation to duration/degree of exposure to asbestos or smoking history Latency period 20-45 years Earlier than asbestosis Later than asbestos-related lung cancer

MESOTHELIOMA Imaging findings Extensive irregular lobulated bulky pleural-based masses typically >5 cm / pleural thickening (60%) Exudative / hemorrhagic unilateral pleural effusion (30-60-80%) without mediastinal shift; effusion contains hyaluronic acid in 80-100%; bilateral effusions (in 10%) Distinct pleural mass without effusion (<25%) Associated with pleural plaques in 50% = pathologic HALLMARK of asbestos exposure Pleural calcifications (20%) Circumferential encasement = involvement of all pleural surfaces (mediastinum, pericardium, fissures) as late manifestation

MESOTHELIOMA Extension into inter-lobar fissures (40-86%) Rib destruction in 20% (in advanced disease) Ascites (peritoneum involved in 35%)

mesothelioma

THREE FUNCTIONS FOR GOOD QUALITY High KV technique(penetrating power of X-ray beam) .A voltage of 100/120 KV X-rays tube current Exposure time( low exposure time)

ADVANTAGE OF HIGH KV TECHNIQUE Optimal contrast between lungs and bones Good visualization of mediastinal structures Low exposure time reduces motion artefacts caused by respiratory or cardiac movement.

TECHNIQUE: CHEST X-RAY PA Quality control 1.Film correctly centred 2.Film correctly exposed 3.Film correctly developed/Digital well processed 4.Critical structures visualized from lung apices to below diaphragm(Visualize costophrenic borders up the costophrenic angle

FILM QUALITY PA or AP view Upright /Erect or supine Breath: Inspiration or Expiration Penetration : Under or over penetration. Rotation

PA vs AP views Scapula is seen in periphery of thorax Clavicle project over lung fields Posterior ribs are distinct Position of markers Scapulae over lung fields Clavicles are above the apices of the lung fields Position of Markers Anterior ribs are distinct

PITFALLS OF CHEST X-RAY INTERPRETATION Poor inspiration Over or under exposure Rotation

HOW TO QUALIFY A GOOD QUALITY RADIOGRAPH Verification of Name, Identity number and Date of examination. Verification of factors of good quality Analysis of thoracic wall and thoracic skeleton. Analysis of mediastinum Analysis of both lung fields Analysis hidden areas(Supra clavicular , behind the heart, below the diaphragm

INTERPRETATION

ASSESSMENT OF CARDIAC SIZE

TECHNICAL QUALITY FOUR GRADES OF QUALITY 1.Good 2.Acceptable with no technical defect likely to impair classification of the radiograph of pneumoconiosis. 3.Acceptable with some technical defects but still adequate for classification 4.Unacceptable for classification purposes

If technical quality is not Grade 1 then comment on defects Over exposure Under exposure Blurring no sharpness Lack of contrast Inadequate positioning Scapulae overlying/Cut offs Artefacts due to processing Other artefacts/hair, jewellery etc Visible grid Wrong film screen combination

GOOD QUALITY WITH DIGITAL CHEST RADIOGRAPHY Advantages 1.Imaging quality adjusted computer processing 2.Easy quick imaging processing/easy storage of images long term on PACS 3.No darkroom and chemical processing Disadvantages 1.Costly initial investment and costly maintenance costs 2. Significant training in digital needed

VIEWING BOXES Viewing boxes should be clean with uniform intensity of illumination. At least 80 w florescent tubes Film reader distance of at least 25 cm(near enough to see a shadow of 1mm Low room light (no direct light) Environment: quiet room Time

DIGITAL MONITORS High definition diagnostic monitors of at least 3 megapixels as required by radiation control board Low room light (no direct light) Environment: quiet room Time

VIEWING OF IMAGES I It is not recommended to Displaying digital images on a personal computer rather than a medical grade monitor Comparing subject digital images to analogue ILO 2000 standard radiographs displayed on a viewing box Viewing subject digital images or analogue images in formats reduced to less than two thirds of the full size. Using images printed on paper for classification

OBJECTIVE OF ILO CLASSIFICATION . To codify the radiographic abnormalities of pneumoconiosis in a simple, reproducible manner. The Classification neither defines pathological entities nor takes into account working capacity. It does not imply legal definitions of pneumoconiosis for compensation purposes. It does not set or imply a level at which compensation is payable

ILO Classification Parenchymal abnormalities Small opacities: small opacities are classified according to shape and size Small rounded opacities P up to 1.5 mm Q about1,5 mm to 3mm R exceeding 3mm

SMALL IRREGULAR OPACITIES s < 1.5 mm t 1.5 to < 3 mm u 3 to < 10 mm

ILO Classification Parenchymal abnormalities Lung zones: each lung is divided into upper ,middle and lower zones Profusion: The concentration of small opacities are classified on the 4 point major category( 0,1,2 or 3. With each major category divided into 3 giving 12 order sub categories of increasing profusion(0,0/1,1/0,1/1,1/2,2/1,2/2,2/3, 3/2,3/3 and 3/+

ILO Classification Parenchymal abnormalities Category 3 represents most profuse The major category(first number) represents the profusion best fit the film. The minor category(second number) represents the profusion seriously considered as an alternative Category 0 refers to absence of small opacities

ILO Classification Parenchymal abnormalities LARGE OPACITIES:A large opacity is defined as any opacity greater than 1cm Category A:One or more large opacities whose combined dimension does not exceed 50 mm Category B: :One or more large opacities with a combine dimension that exceed 50mm but does not exceed the equivalent area of the right upper lobe. Category C: exceeds the equivalent area of the right upper lobe.

ILO Classification Pleural abnormalities Pleural abnormalities are reported with respect to the type Pleural plaques or diffuse thickening Location: chest wall, diaphragm , mediastinal, peritoneal and para-spinal Presence of calcified plaques and pleural calcification Width: only of in profile pleural thickening seen along the chest wall edge Extent: combined distance for involved chest wall

PLEURAL ABNORMALITIES Circumscribed (plaques) or diffuse Site (R/L) – both sides are recorded separately Width a < 5 mm b maximum width > 5 and < 10 mm c maximum width > 10 mm Extent 1 < ¼ lateral projection of chest wall 2 > ¼ but < ½ lateral projection of chest wall 3 > ½ lateral projection of chest wall Pleural Calcification Diaphragms and chest walls recorded separately

ILO Classification Any other abnormality There are about 29 symbols representing important features related to dust diseases and other etiologies e.g. : tba: active TB, em: emphysema ,es: eggshell, hi : hilar- adeno-pathy, ef: effusion.

SYMBOLS di = marked distortion of intrathoracic organs ef = effusion em = definite emphysema (usually COPD) es = eggshell calcification of hilar and/or mediastinal lymph nodes fr = fractured rib(s) hi = enlarged lymph nodes, hilar and/or mediastinal ho = honeycomb lung

SYMBOLS id = ill defined diaphragm (> 1/3 of 1 hemi-diaphragm ih = ill defined heart outline (> 1/3 of left heart outline) kl = septal lines (Kerley B lines) od = other disease pi = interlobular fissure pleural thickening px = pneumothorax rp = rheumatoid pneumoconiosis (Caplan’s syndrome) tb = tuberculosis

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