Respiratory (2) Flashcards
Define idiopathic pulmonary fibrosis
A chronic, progressive, interstitial restrictive lung disease of an unknown cause which results in fibrosis and thickening of interstitial lung tissue and dyspnoea.
Summarise the aetiology of idiopathic pulmonary fibrosis
Unknown cause
Occurs in genetically predisposed patients
Type II pneumocytes overproliferate, causing increased numbers of myofibroblasts which produce collagen in the interstitium
Risk factors: Age 50-70 Male Smoking Occupational dust, metal or wood exposure GORD Diabetes Family history
Summarise the epidemiology of idiopathic pulmonary fibrosis
More common in males
More common with increasing age - age at presentation 60-70 years old
Familial form presents younger - 55 to 60 y/o
What are the presenting symptoms of idiopathic pulmonary fibrosis?
Progressive symptoms Dry, non-productive, irritative cough - does not respond to anti-tussives Dyspnoea on exertion NO WHEEZE Weight loss Fatigue Malaise
What are the signs on physical examination of idiopathic pulmonary fibrosis?
Clubbing
Cyanosis
Dry late-inspiratory bibasilar fine crackles
Signs of right heart failure in advanced disease
What are the appropriate investigations for idiopathic pulmonary fibrosis?
CXR:
Usually normal at presentation.
Early disease may show ground glass shadowing.
Late stage disease shows reticulonodular shadowing and signs of cor pulmonale.
High-resolution CT: more sensitive in early disease the an CXR. Reticular opacities, honeycombing, increased thickness of interstitial space
Pulmonary Function Tests: Restrictive features - decreased FEV1, FVC, TLC, lung compliance, normal or increased FEV1/FVC
ANA, anti-CCP and Rheumatoid Factor: 1/3 of patients are positive for ANA or RF
Bronchoalveolar Lavage: exclude infections and malignancy
Lung Biopsy: gold standard for diagnosis BUT may not be appropriate - fibrosis, areas of normal surrouded by scar tissue, honeycombing
Define lung cancer
Primary malignant neoplasm of the lungs
Can be small cell or non-small cell
Small cell/oat cell carcinoma - malignant epithelial tumour arising from cells lining the lower respiratory tract
Non-small cell: Adenocarcinoma Squamous cell carcinoma Large cell Bronchial carcinoid
Summarise the aetiology of lung cancer
Small cell carcinoma:
Highly associated with smoking
From small, immature neuroendocrine cells
Aggressive, rapidly metastasising
Adenocarcinoma:
Most common type in female non-smokers
Squamous cell:
Highly associated with smoking
Other risk factors: FHx Radon exposure Asbestos Air pollution Ionising radiation
Summarise the epidemiology of lung cancer
Adenocarcinoma is most common type in non-smokers
Adenocarcinoma - 35%
Squamous cell carcinoma - 30%
Small cell carcinoma - 30%
Large cell carcinoma - 15%
Non-small cell 3 times more common in men
What are the presenting symptoms of lung cancer?
Local symptoms:
Cough
Dyspnoea
Weight loss, fever, fatigue, night sweats
Infiltration into blood vessels - haemoptysis
Symptoms from compression of SVC - facial swelling, dyspnoea
Symptoms from compression of laryngeal nerve - hoarse voice
Symptoms from compression of brachial plexus - pain in shoulder and arm
Small cell:
Symptoms from SIADH
Symptoms of due to ACTH paraneoplastic Cushing’s - weight gain, fatigue
Symptoms of Lambert-Eaton syndrome - weakness which improves with use
Squamous cell carcinoma:
Symptoms of hypercalcaemia due to paraneoplastic PTHrp release - abdominal pain, confusion, bone pain, constipation
What are the signs on physical examination of lung cancer?
Wheeze, crackles, reduced breath sounds, dullness to percussion
Weight loss
Horner’s syndrome due to pancoast tumour - miosis, anhydrosis, ptosis
Signs of Cushing’s if paraneoplastic small cell
SVC compression: facial congestion, distension of neck veins, upper limb oedema
Brachial Plexus: wasting of small muscles of hand
Hypertrophic Osteoarthropathy - clubbing, painful swollen wrist/ankles (periosteal new bone formation) - adenocarcinoma
Signs of metastases:
Hepatomegaly
Supraclavicular lymphadenopathy
What are the appropriate investigations for lung cancer?
CXR - coin lesion, single or multiple pulmonary nodules, Lobar Collapse, Pleural Effusion, Mediastinal or Hilar Fullness
Small cell and squamous cell likely central mass
CT chest, liver, adrenals - non-calcified nodule, useful for staging
Bronchoscopy and biopsy
Sputum cytology - malignant cells
FBC - may show anaemia
U&E’s - elevated calcium due to PTHrp paraneoplastic squamous cell carcinoma
LFTS (normal/elevated if lone, increased ALP in bone metastases)
Isotope bone scans
Define extrinsic allergic alveolitis
An excessive immune response to inhaled antigens, usually from occupational exposures to organic dusts, leading to inflammation of the alveoli and distal bronchioles.
Summarise the aetiology of extrinsic allergic alveolitis
Inhalation of antigenic dusts (microbes, animal proteins) induce a hypersensitivity response in susceptible individuals
Farmer’s lung - inhalation of thermophilic actinomycetes from damp, moudly hay
Pigeon fancier’s lung - inhalation of bird poo and feathers
Malt worker’s lung - mouldy barley containing aspergillus
Exposure to inhalation of actinomycetes from mouldy sugar cane
Humidifier lung: water containing bacteria and Naegleria (amoeba)
Risk Factors:
Smoking
Viral infection
Exposure to: avian protein, mould and bacterial antigen
Summarise the epidemiology of extrinsic allergic alveolitis
UNCOMMON (2% occupational lung disease)
50% reported cases affect farm workers
6-21% of pigeon breeders found to develop extrinsic allergic alveolitis
