1.Pulmonary Vascular Disease 2.Pleural Disease Prof. Frank Carey

Pulmonary Circulatuion r Dual supply l Pulmonary arteries l Bronchial arteries r Low pressure system r Pulmonary artery receives entire cardiac output (a filter)

Low pressure system…. r Thin walled vessels r Low incidence of atherosclerosis At normal pressures

Pulmonary Oedema r Accumulation of fluid in the lung l Interstitium l Alveolar spaces r Causes a restrictive pattern of disease

Pulmonary Oedema (causes) 1. Haemodynamic ( hydrostatic pressure) 2. Due to cellular injury i. Alveolar lining cells ii. Alveolar endothelium Localised – pneumonia Generalised – adult respiratory distress syndrome (ARDS)

ARDS r Diffuse alveolar damage syndrome (DADS) r Shock lung l Causes include sepsis, diffuse infection (virus, mycoplasma), severe trauma, oxygen

Pathogenesis of ARDS Injury (eg bacterial endotoxin) r Infiltration of inflammatory cells r Cytokines r Oxygen free radicals r Injury to cell membranes

Pathology of ARDS r Fibrinous exudate lining alveolar walls (hyaline membranes) r Cellular regeneration r Inflammation

ARDS with hyaline membrane

ARDS – cellular reaction

Outcome of ARDS r Death r Resolution r Fibrosis (chronic restrictive lung disease

Neonatal RDS r Premature infants r Deficient in surfactant (type 2 alveolar lining cells r Increased effort in expanding lung physical damage to cells

Embolus r A detached intravascular mass carried by the blood to a site in the body distant from its point of origin r Most emboli are thrombi – others include gas, fat, foreign bodies and tumour clumps

Pulmonary Embolus r Common r Often subclinical r An important cause of sudden death and pulmonary hypertension 95% + of emboli are thromboemboli

Source of most pulmonary emboli….. r Deep venous thrombosis (DVT) of lower limbs

Risk factors for PE are those for DVT…. 1. Factors in vessel wall (eg endothelial hypoxia) 2. Abnormal blood flow (venous stasis) 3. Hypercoaguable blood (cancer patients, post-MI etc) - Virchow’s triad

Effects of PE r Sudden death r Severe chest pain/dyspnoea/haemoptysis r Pulmonary infarction r Pulmonary hypertension

Effects of PE depend on… r Size of embolus r Cardiac function r Respiratory function

Effect of embolus size… r Large emboli l Death l Infarction l Severe symptoms r Small emboli l Clinically silent l Recurrent pulmonary hypertension

Pulmonary Infarct (ischaemic necrosis) r Embolus necessary but not sufficient r Bronchial artery supply compromised (eg in cardiac failure)

Pummonary Embolus

Pulmonary infarct – tumour embolus

Pulmonary Hypertension r Primary (rare, young women) r Secondary

Pulmonary Hypertension (mechanisms) r Hypoxia (vascular constriction) r Increased flow through pulmonary circulation (congenital heart disease) r Blockage (PE) or loss (emphysema) of pulmonary vascular bed r Back pressure from left sided heart failure

Morphology of pulmonary hypertension r Medial hypertrophy of arteries r Intimal thickening (fibrosis) r Atheroma r Right ventricular hypertrophy r Extreme cases (congenital heart disease, primary pulmonary hypertension) – plexogenic change/necrosis

Pulmonary artery – intimal fibrosis

Plexiform lesion – primary pulmonary hypertension

“Cor Pulmonale” r Pulmonary hypertension complicating lung disease r Right ventricular hypertrophy r Right ventricular dilatation r Right heart failure (swollen legs, congested liver etc)

Cardiomegaly due to right ventricular dilatation

Right ventricular hypertrophy and dilatation

The Pleura r A mesothelial surface lining the lungs and mediastinum r Mesothelial cells designed for fluid absorption r Hallmark of disease is the effusion

Pleural Effusion r Transudate (low protein) l cardiac failure l hypoproteinaemia r Exudate (high protein) l pneumonia l TB l connective tissue disease l malignancy (primary or metastatic)

Pleural effusion

Purulent Effusion Full of acute inflammatory cells r Empyema r Can become chronic

Pneumothorax Air in pleural space r Trauma r Rupture of bulla

Large bullae

Pleural Neoplasia r Primary l benign (rare) l malignant mesothelioma r Secondary l common (adenocarcinomas - lung, GIT, ovary)

Mesothelioma r Asbestosis related r Increasing incidence r Mixed epithelial/mesenchymal differentiation r Dismal prognosis

Mesothelioma

Pleural biopsy - mesothelioma

Metastases in Pleura

Differential diagnosis of malignant effusions….. r Cytology, biopsy r Difficult r Immunohistochemistry for lineage specific antigens may help r Medicolegal importance