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MRCP Clinical Sciences > Respiratory Medicine > Flashcards

Respiratory Medicine Flashcards

1
Q

Definition of Sarcoidosis

A

A chronic, multisystem granulomatous disease characterized by the presence of

  1. Noncaseating granulomas, and
  2. Chronic interstitial lung disease (fibrosis)
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2
Q

Epidemiology of Sarcoidosis

A
  • Most common non-infectious granulomatous disease
  • Accounts for 25% of chronic ILD
  • Common in blacks & non-smokers
  • Peak incidence - 20-39 yoa
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3
Q

What is the characteristic histological lesion in Sarcoidosis?

A

A granuloma composed of macrophages, lymphocytes and epithelioid histiocytes, which fuse to form multinucleate giant cells

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4
Q

Clinical features of Sarcoidosis?

A

Lungs - dyspnoea, non-productive cough, malaise, WL

  • Noncaseating granulomas in the interstitium as well as mediastinal and hilar lymph nodes
  • Granulomas contain multinucleated giant cells (MGCs)

Extrapulmonary disease

Lymphadenopathy

  • Painless, rubbery LN enlargement (esp Blacks)
  • Cervical & scalene muscle LNs most commonly

Skin

  • Lupus pernio - violaceous rash on the nose & cheeks
  • Erythema nodosum - Nodular painful lesions containing noncaseating granulomas

Eyes

  • Acute anterior uveitis - 25% (uvea - pigmented middle layer of the eye)
    • Blurry vision, glaucoma, corneal opacities

GI tract

  • Liver
    • Mostly subclinical, but > Granulomatous hepatitis
    • Most common cause of non-infectious cause of hepatitis
    • Hepatomegaly
  • Spleen
    • Splenomegaly

Cardiac

  • May involve the cardiac muscle and the conduction system
    • Arrhythmias, BBB or complete heart block

Hypercalcaemia (10-20%)

  • Increased synthesis of 1-α-hydroxylase in the granuloma by the MCGs > increased conversion of vit D to its active form (Calcitriol)

Hypercalciuria (30-50%)

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5
Q

What is the effect of Calcitriol on calcium in the body?

A

Calcitriol (vit D) increases blood calcium levels

  • Promotes absorption of dietary Ca from the GI tract
  • Increases renal tubular reabsorption of Calcium
  • Stimulates the release of Ca from the bone
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6
Q

What is Lofgren syndrome?

A

The combination of

  • Bilateral hilar lymphadenopathy
  • Erythema nodosum
  • Swinging fever
  • Polyarthralgia

Excellent prognosis

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7
Q

What is Heerfordt-Waldenstrom syndrome?

A

Uveoparotid fever

  • Parotid enlargement, fever and uveitis secondary to sarcoidosis
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8
Q

Diagnosis of Sarcoidosis

A

BHL + EN in a young adult - diagnostic of acute sarcoidosis

BHL + EN + fever + arthralgia - Lofgren syndrome

Main differential

  • TB
  • Lymphoma

Thoracic CT

  • Hilar & mediastinal lymphadenopathy
  • Nodules along bronchi, vessels
  • Ground-glass shadowing

Tissue biopsy (transbronchial & endobronchial, or skin biopsy of one of the plaques)

  • Non-caseating granulomas in 85-90%

Elevated ACE & Ca - but non-specific

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9
Q

Grading of CXR changes in Sarcoidosis

A

Stage 0: clear CXR

Stage 1: BHL

Stage 2: BHL + pulmonary infiltrates

Stage 3: Diffuse pulmonary infiltration

Stage 4: Pulmonary fibrosis

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10
Q

Treatment of Sarcoidosis

A

Stage 0 & 1 - disease usually resolves spontaneously

Stage 2

  • Serial lung function tests + treatment if progressive deterioration

Treatment

  • Steroid therapy indicated for
    • Hypercalcaemia & hypercalciuria resistant to dietary restriction
    • Opthalmological & neurological Cx
  • Treatment regime
    • 0.5 mg/kg/day Prednisolone for the first 4 weeks, then wean down to the lowest maintenance dose possible
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11
Q

Definition of Idiopathic Pulmonary Fibrosis

A

Chronic, progressive fibrosing interstitial pneumonia of unknown cause occurring primarily in older adults, characterised by usual interstitial pneumonia (UIP) on lung biopsy, in the absence of an obvious cause

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12
Q

What is meant by Usual Interstitial Pneumonia (UIP)?

A
  • Honeycombing
  • Minimal cellular inflammation
  • Regions of proliferating myofibroblasts (fibroblastic foci) occurring in a patchy distribution
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13
Q

Epidemiology of IPF

A
  • A disease of middle-aged and elderly people (40-70)
  • More common in men
  • Possibly the result of an autoimmune response to inhaled environmental antigens (?metal, wood)
  • Association with EBV
  • Accounts for 30% of RLD, 80% of ILD (Interstitial LD)
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14
Q

What is the likely pathogenesis of IPF?

A
  1. Repeated cycles of alveolitis triggered by ?agent
  2. Release of cytokines produces interstitial fibrosis
  3. Alveolar fibrosis leads to proximal dilatation of the small airways
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15
Q

Treatment of IPF

A

Limited options

  • Pirfenidine
    • ​An immunosuppressant with anti-inflammatory and anti-fibrotic effects
    • May be used in those with a FVC of 50-80%
    • Shown to slow the rate of FVC decline & disease progression
  • Single-lung transplantation in those < 65
  • Pulmonary rehabilitation
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16
Q

Drugs causing pulmonary fibrosis

A

BBCMAN

Bleomycin (chemo)

Busulfan (chemo)

Cyclophosphamide (chemo + immunosuppressant)

Methotrexate (chemo + immunosuppressant)

Amiodarone

Nitrofurantoin

17
Q

Upper vs Lower zone lung fibrosis

A

Upper zone fibrosis - CHARTS

  • Coal worker’s pneumoconiosis
  • Histiocytosis/Hypersensitivity pneumonitis
  • Ankylosing spondylitis
  • Radiation
  • Tuberculosis
  • Silicosis/Sarcoidosis

Lower zone fibrosis

  • IPF
  • CTD - Connective tissue diseases (esp SLE)
  • Drug-induced - BBCMAN
  • Asbestosis
18
Q

Extrinsic allergic alveolitis / Hypersensitivity pneumonitis

A

A condition caused by hypersensitivity-induced lung damage due to a variety of inhaled organic particles

  • Thought to be largely caused by
    • Type III hypersensitivity (IgG)
      • Immune-complex mediated tissue damage
    • Type IV (delayed hypersensitivity) also thought to play a role
      • Esp in the chronic phase
19
Q

What EAA/HSP and their causative organisms do you know?

A
  • Bird fanciers’ lung:
    • Avian proteins in excreta
  • Farmers lung: spores of Saccharopolyspora rectivirgula
    • Mouldy hay
  • Malt worker’s lung: Aspergillus clavatus
  • Mushroom workers’ lung: thermophillic actinomycetes
  • Ventilation pneumonitis
    • Inhabitants of air-conditioned buildings where thermophilic actinomycetes grow in the humidification system
  • Bagassosis
    • Exposure to Thermoactinomyces sacchari in sugar cane processors
20
Q

Clinical features of Extrinsic Allergic Alveolitis

A

Acute

  • Develops hours after exposure to high concentrations
  • SOB + ‘flu-like’ Sx - fever, headache, myalgia
  • Short-lived symptoms, usually completely resolves within 48 hours
  • Inspiratory crackles

Subacute/chronic

  • Cough, SOB, fatigue, weight loss
  • Clubbing if ass with irreversible pulmonary fibrosis
21
Q

How is a diagnosis of EAA made?

A

Diagnosis made by establishing

  • A Hx of exposure to antigen
  • Demonstration of precipitating antibodies in the patient’s serum

CXR

  • General haze with diffuse small nodules
  • Chronic: progressive upper/mid-zone fibrosis

BAL - lymphocytosis (>40%)

Precipitins - specific antibodies in serum against the identified antigen

Blood - no eosinophilia

Corticosteroids

  • Accelerate the rate of recovery from an acute attack
  • Not generally helpful once established fibrosis has developed
22
Q

Pulmonary fibrosis in EAA

A
  1. Multiple episodes of acute exposure to agents causing EAA, or
  2. Long-term, low-grade exposure (owners of budgerigars)

Will lead to irreversible pulmonary fibrosis

Presentation

  • Progressive dyspnoea
  • Weight loss
  • Fatigue

Prompt diagnosis of EAA necessary, because the disease is reversible when diagnosed early

23
Q

What are the main types of Altitude-related disorders?

A
  • Acute Mountain Sickness
  • High Altitude Pulmonary Oedema
  • High Altitude Cerebral Oedema
24
Q

Discuss Acute Mountain Sickness (AMS)

A

Acute Mountain Sickness (AMS)

  • Generally self-limiting
  • Starts to occur above 2,500 - 3,000 m
  • Develops gradually over 6-12 hours, can last a number of days
  • Features
    • Headache
    • Nausea
    • Fatigue

Prevention and treatment of AMS

  • The risk of AMS positively correlated to physical fitness
  • Gain altitude at no more than 500 m per day
  • Acetazolamide (a carbonic anhydrase inhibitor) used to prevent AMS
  • Treatment - descent
25
Q

High Altitude Pulmonary Oedema (HAPE)

and

High Altitude Cerebral Oedema (HACE)

A

Both are potentially fatal conditions

HAPE - Presents with classical pulmonary oedema features

Mx of HAPE

  • Descent
  • Nifedipine
  • Oxygen if available

HACE - Presentes with headache, ataxia, papilloedema

Mx of HACE

  • Descent
  • Dexamethasone
26
Q

Alpha1-Antitrypsin deficiency

A

A common inherited condition caused by a lack of a protease inhibitor (Pi) normally produced by the liver

The role of A1At

  • To protect cells from enzymes such as neutrophil elastase

It classically causes emphysema (i.e. COPD) in patients who are young and non-smokers

Genetics

  • Located on chromosome 14
  • Inherited in AR/co-dominant fashion
  • Alleles classified by their electrophoretic mobility
    • M - for normal
    • S - for slow
    • Z - for very slow
  • Phenotypes
    • Normal = PiMM
    • Homozygous PiSS (50% normal A1AT levels)
    • Homozygous PiZZ (10% normal A1AT levels)

Features

  • Patients who manifest disease - usually the PiZZ phenotype
  • Lungs - panacinar emphysema, most marked in lower lobes
  • Liver
    • ​Adults - cirrhosis & hepatocellular carcinoma
    • Children - cholestasis

Investigations

  • A1AT concentrations
  • Spirometry - obstructive picture, large lung volumes, reduced KCO

Management

  • No smoking
  • Supportive - bronchodilators, physiotherapy
  • IV alpha1-antitrypsin protein concentrates
  • Surgery - lung volume reduction surgery, lung transplantation
27
Q

Eligibility for LTOT

A

Patients are eligible for LTOT if they exhibit all of the following:

  • PO2 on air < 7.3 kPa
  • Normal/elevated PCO2
  • FEV1 < 1.5 L / <40% of predicted
  • PO2 7.3-8.0 kPa with evidence of
    • Pulmonary hypertension, or
    • Polycythaemia, or
    • Peripheral oedema, or
    • Nocturnal hypoxaemia

ABG must be measured when the pt is clinically stable

  • At least 6 weeks post-exacerbation, and
  • On two occasions that are at least 3 weeks apart
  • The PO2 on O2 therapy should be >8 kPa without an unacceptable rise in PCO2
  • O2 should be given via a concentrator for at least 15 h/day
  • Pt must stop smoking before LTOT is considered

MRCP Clinical Sciences (1 decks)

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