Sarcoidosis

Question 1

Sarcoidosis : Definition

Answer 1

1. Sarcoidosis is a multisystem inflammatory disorder characterized by the formation of granulomas, which are clumps of inflammatory cell
2. These granulomas can develop in various organs, most commonly affecting the lungs and lymph nodes.
3. Non caseating Granulomas - small, inflammatory nodules composed of immune cells, particularly macrophages, epithelioid cells, and lymphocytes

Question 2

Sarcoidosis : Pathophysiology

Answer 2

1. Unknown trigger
2. Immune cell activation - particularly macrophages
3. Macrophage engulf foreign particles - recruit other immune cells such as lymphocytes etc
4. Aggregates of immune cells clump together - Granulomas formed
5. Granuloma - multisystem -> Generate inflammatory response and tissue damage

Question 3

Sarcoidosis : Clinical features

Answer 3

The symptoms of sarcoidosis can vary widely and depend on the organs involved.
Cough, dyspnea, chest pain, and constitutional symptoms such as fever, fatigue, andweight loss
* acute:erythema nodosum, bilateral hilar lymphadenopathy, swinging fever, polyarthralgia
* insidious: dyspnoea, non-productive cough, malaise, weight loss
* ocular: uveitis
* skin: lupus pernio
* hypercalcaemia: macrophages inside the granulomas cause an increased conversion of vitamin D to its active form (1,25-dihydroxycholecalciferol)

Question 4

Sarcoidosis : Investigation

Answer 4

CXR : infiltrates and bihilar lymphadenopathy, fibrosis
Restrictive lung disease - pulmonary fibrosis
Bloods : High ACE, High calcium

Question 5

Tuberculosis : pathophysiology

Answer 5

Inhalation of Mycobacterium tuberculosis via droplet → deposition in the lungs (alveoli) → engulfed by alveolar macrophages → proliferates in macrophages → release → immune response.
* Immediate clearance of the organism: the majority of individuals never develop the clinical disease.
* **Primary disease: rapid progression to active disease if the immune response is inadequate.
* Latent infection (with or without subsequent reactivation disease):
* Non contegious
* TH1 response →caseating granulomaformation (caseous centre with necrotic material, surrounded by lymphocytes** and macrophages) → successful containment.
* Reactivation disease:
* Occurs when the immune response is suppressed.
* Onset of the active disease years after latent infection.

Question 6

Tuberculosis : Clinical features

Answer 6

Constitutional symptoms:
* Fever: usually gradual onset and low-grade.
* Night sweats: maybe drenching.
* Weight loss,anorexia, and malaise are also common.

Pulmonary tuberculosis:
* Most common.
Dyspnoea,cough(+/-haemoptysis), chest pain.
* Cough: over 2 to 3 weeks; initially dry, later productive.
* Chest examination: crackles, bronchial breath sounds, or maybe normal.

Question 7

Tuberculosis : investigation

Answer 7

Latent infection (no active signs of TB)
Tuberculin skin tests
interferon-gamma release assays - preferred if hx of BCG vaccination

Active signs of TB
CXR : Bilar lymphadenopathy, upper lobe aviation
Sputum sample - 3x required
Acid fast stain - identify bacilli
Gold standard : Sputum culture

Question 8

Tuberculosis : Management

Answer 8

1. Latent infection - r/o active infection
   * Isoniazid - 9 months
   * Rifampicin for 4 months
2. Active infection
   * The recommended regimen for drug-susceptible individuals is:
   Intensive phase:two months of isoniazid + rifampin + pyrazinamide + ethambutol.
   Continuation phase:four months of isoniazid + rifampin.

Question 9

Tuberculosis : Drug SE

Answer 9

1. Rifampicin - Orange secretions, enzyme inducer
2. Isoniazid - Peripheral neuropathy: prevent with pyridoxine (Vitamin B6), Agranulocytosis, Liver enzyme inhibitor
3. Pyrazinamide Hyperuricaemia causing gout
4. Ethambutol - Optic neuritis: check visual acuity before and during treatment

Question 10

The most common causes of bilateral hilar lymphadenopathy aresarcoidosisandtuberculosis.