Respiratory JC018: Pleural Effusion In A Chronic Smoker: Pleural Effusion, Lung Cancer Flashcards
Case: 64 yo male, chronic smoker, retired restaurant worker
- Pleural effusion on CXR
—> Diagnostic + Therapeutic tapping x2
—> Exudative changes
—> Atypical cells with large N/C ratio (need to rule out malignancy)
—> but Pleural fluid cytology + Percutaneous biopsy non-diagnostic
Pathophysiology of pleural effusion
Pleural space: between parietal + visceral pleura
Imbalance across membranes —> movement of fluid from vascular space to pleural space —> accumulation
Parietal pleura (Arterial capillary) + Visceral pleura (Venous capillary):
1. Hydrostatic pressure (push fluid into pleura)
2. Oncotic pressure (draw fluid)
3. Lymphatic drainage (draw fluid)
4. Capillary permeability (leakage of fluid into pleural cavity)
Hydrostatic pressure
↑ due to abnormal fluid retention:
1. **Congestive HF
2. **Renal failure
3. Other forms of volume overload
Oncotic pressure
↓ mainly due to ↓ plasma protein (esp. Albumin):
1. **Cirrhosis
2. **Nephrotic syndrome
3. Severe malnutrition
4. ***Other forms of hypoalbuminemia
Capillary permeability
↑ due to **pleural inflammation:
1. **Infection of lung / pleura (including TB)
2. Collagen vascular disease (involving pleura)
3. **Malignant involvement of pleura
4. Intra-abdominal process (e.g. **pancreatitis, ***liver abscess)
Lymphatic drainage
↓ due to:
1. ***Malignant infiltration of mediastinal, pulmonary, pleural lymphatics
—> ↑ pressure in downstream lymphatics
- Necrotising / ***Granulomatous infections
***Transudative vs Exudative fluid
Transudative:
1. ↑ Hydrostatic pressure
2. ↓ Oncotic pressure
—> ***Pure water movement
Exudative:
1. ↑ Capillary permeability
2. ↓ Lymphatic drainage
—> Direct leakage
—> ***Protein movement also
***Investigations of Transudative vs Exudative fluid
Diagnostic thoracentesis (aka pleural tapping) + ***Pleural fluid analysis
記: ABCCM
- ***Appearance
- turbid
- blood stained
- clear / straw colour - Biochemistry
- ***Protein + LDH (Light’s criteria)
- Glucose, pH - ***Cell count + differential
- Empyema: Neutrophil predominant
- Tuberculous pleurisy: Lymphocyte predominant - ***Cytology
- malignancy / atypical cells
(- 70% yield (CL Lai)) - ***Microbiology
- smear for AFB / other bacteria
***Light’s criteria
Exudative effusion, ***>=1 of following:
- Pleural fluid protein / Serum protein > 0.5
- Pleural fluid LDH / Serum LDH > 0.6
- Pleural fluid LDH > 2/3 normal upper limit for serum
Glucose, pH:
- ↓ together in some exudative process e.g. empyema, rheumatoid pleurisy
Other investigations
- Percutaneous pleural biopsy
- ***exudative effusion
- esp. to confirm TB / cancer - Thoracoscopy / ***Pleuroscopy
Aim: Identification of primary cause of pleural fluid formation
Lung cancer epidemiology
Male patients:
- Predominant
- 80% smokers
Female patients:
- <40% smokers
- >75% **Adenocarcinoma
- high prevalence compared to other countries
—> Environmental factors: Passive smoking, diet, cooking fumes
—> Genetic factors: **EGFR gene mutation important in some non-smoking patients with adenocarcinoma
Pathogenesis of Adenocarcinoma and SCC
Heterogeneous
SCC: arise from ***Central compartment (Bronchial structures)
- Series of transition: Normal epithelium —> Metaplasia —> Dysplasia —> CIS —> SCC
Adenocarcinoma: **Peripheral compartment (Bronchiolo-alveolar structures)
- Not very known
- **Variable histology (can be ∵ heterogeneous genetics abnormalities)
- Normal alveolar / Bronchiolar epithelium
—(less known changes)—> ***Atypical adenomatous hyperplasia (AAH)
—> Invasive Adenocarcinoma
***WHO classification of lung tumour histology
Epithelial tumours:
1. Non-small cell lung cancer (85%)
- Adenocarcinoma (45-55%)
- SCC (20-30%)
- Large cell carcinoma (5-10%)
- Small cell lung cancer (5-10%)
- Mixed
Mesothelial tumours:
1. Malignant mesothelioma
Miscellaneous malignant tumours
***Clinical presentation of lung cancer
Very variable:
- **Patch of consolidation / **Lung mass / **Diffuse involvement / **Pleural effusion
Identification of patients based on:
- Clinical S/S
- Clinical syndrome
- Incidental findings on asymptomatic individuals
- Identification of at risk population
***S/S of lung cancer
- Radiological abnormality only
- ***Constitutional symptoms
- malaise
- ↓ appetite
- ↓ body weight - Primary lesion
- Bronchial mucosa ulceration
—> cough, sputum, ***haemoptysis
-
**Obstructive
—> partial: **wheeze, unresolved pneumonia, dyspnea
—> complete: ***lung collapse
- Intrathoracic spread
- Along lymphatics to both lungs —> **Lymphangitis carcinomatosis: cough, dyspnea (Diffusely opacified both lung fields, DDx: Miliary TB (SpC Medicine))
- **Pleura —> Pleural effusion: chest pain, dyspnea
- **Pericardial effusion —> Cardiac tamponade: dyspnea
- **SVC obstruction: dyspnea, stridor, dysphagia, face swelling
- **L Recurrent laryngeal nerve (L>R ∵ longer course (self notes)): hoarseness
- **Brachial plexus (C8-T2) —> **Pancoast’s syndrome (Davidson): pain in shoulder / arm
- **Inferior cervical sympathetic ganglion —> **Horner: loss of sweating on 1 side of face
- **Esophagus: dysphagia
- ***Chest wall, Ribs: chest pain, swelling - Extra-thoracic manifestations
- Cachexia
- Clubbing
- Supraventricular LN + cervical LN enlargement
- **Liver: hepatomegaly, deranged LFT
- Brain: seizures, change in personality, vomiting
- **Bone: pathological fractures, hypercalcaemia, bone pain
- Adrenal: cortisol insufficiency (rarely)
- ***Spinal cord: cord compression
- Skin
- Choroidal: impaired VA
- Unexplained anaemia - Paraneoplastic syndrome (Systemic non-metastatic syndrome)
- CT
—> **Clubbing, **Hypertrophic pulmonary osteoarthropathy (HPOA): arthralgia, pain, tenderness of extremities
- Ectopic hormones
—> ADH (↓ Na) (e.g. **SIADH) (SCLC (Davidson)): weakness, confusion
—> *ACTH (↓ K) (SCLC (Davidson)): weakness
—> Parathyroid Like-peptide (PLP) (↑ Ca): polyuria, thirst, confusion - Neuromuscular
—> Encephalopathy: dementia, confusion
—> **Cerebellar degeneration: ataxia, clumsiness
—> **Peripheral neuropathy: paresthesia, weakness
—> Myasthenia-like (Lambert-Eaton (SCLC (web)))
—> ***Dermatomyositis (rmb to rule out other head/neck cancer)
