21. Tuberculosis and Sarcoidosis

Question 1

Distinguish between TB and sarcoidosis in dx, tx, and prognosis.

What is the main cause of TB and what 3 things are needed to contract it?

What are the 3 highest risk groups for TB in London?

What factors led to the decline in TB in the UK?

Answer 1

(pic)

Mycobacterium tuberculosis (aerobic, hides in macrophages, lower lobe 1^o TB, upper lobes in 2^o, mycolic acid waxy coat). Need pathogen, susceptible host, environment.

HIV⁺, homeless, prison.

TB less virulent, BCG vaccination, abx tx, pasteurisation of milk, improved general health, genetic selection, improved housing.

Question 2

What factors led to an increase in TB in London?

What is MDRTB?

What is XDRTB?

What is the DOTS strategt for TB control?

Answer 2

Immigration, travel of UK citizens to endemic country, HIV, increase in equality (more poor, homeless), mini-epidemics, overcrowding in prisons, substance abuse, spitting in public, stopping BCG.

3.5% of all TB, resistant to isoniazid and rifampicin.

9% of all MDRTB, MDR and injectables and FQs. Cure rate 35%. May be resistant to 2^nd line drugs: amikacin, kanamycin, or capreomycin

(Directly Observed Therapy Strategy): political commitment, detect cases accurately + early, standard supervised/supported tx, drug supply consistent, monitor + evaluate.

Question 3

List some common and uncommon TB symptoms.

What are some differential diagnoses of haemoptysis?

Differentiate between the immune response to primary TB and post-primary TB.

Answer 3

Common__: Cough, sputum, fever, malaise, loss of appetite.
Uncommon: haemoptysis, night sweats, wt loss, lymphadenopathy.

(pic) ask: when it started, time of day, amount, colour, streak/blob?

Primary TB: TB with no pre-existing immunity, non-infectious, high mortality, often outside lung, kids + old, HIV co-infection.
Post-primary TB: TB with pre-existing immunity, infectious, cavities with TB biofilm, surprisingly well tolerated, young adults, immunocompetent (CD4, CD8).

Question 4

Describe some of the images in primary and post-primary TB below.

How is TB diagnosed?

Briefly describe the TB MDT.

Answer 4

Primary: (from top L anti-clockwise) Gohn focus -> lymph nodes -> spread -> miliary TB in liver, brain -> fluid around heart -> pleural effusion -> affects bone, skin etc.
Post-primary: Lymphadenopathy. Patchy consolidation, cavitation.

• *SPUTUM** (or other sample): PCR (MTB and drug resistance), MIRU-VNTR (stain typing), culture + drug sensitivity testing.
• *CXR**
• *Inflammatory markers**
• *Histology**.

Question 5

What is the standard TB treatment? Give the drug names, action (bacteriocidal/static, site of action and any adverse effects.

What could non-adherence be due to?

What is the practical approach to TB dx in e.g. a GP?

What does the BCG contain?

Answer 5

Initial phase: 2RHEZ - 8w isoniazid, rifamipcin, pyrazinamide, ethambutol. Continuation phase: 4RH - 16w isoniazid, rifampicin.

(pic)

Drug resistance. Regimen long and SEs common. Only 2m = ‘interrupted’ tx.

Stage 1: Symptoms? If yes on to:
Stage 2: Mantoux if < 35 yo, CXR if >35 yo.
Ix: sputum, CXR (if not done), inflammatory markers, immunological test.

Live, attenuated form of bacteria. Effective against most severe forms of TB, such as TB meningitis in children. Less effective in preventing respiratory disease (most common form in adults).

Question 6

What is sarcoidosis?

Differentiate between the symptoms of TB and sarcoidosis.

Answer 6

Multisystem granulomatous disorder of unknown cause. Exaggerated immune response - abnormal collections of inflammatory cells that form granulomas. Usually begins in lungs, skin, or lymph nodes. Often no, or only mild, symptoms. Heritability varies according to ethnicity. Lots of different genes and several different types of sarcoid e.g. Japanese.

(pic) Sarcoidosis key = breathlessness. No Mantoux response with sarcoid.

Question 7

What do the following histologies show?

How do sarcoidosis, lymphoma and TB compare with:

a) FBC
b) Ca
c) CRP
d) SACE (Serum angiotensin converting enzyme)
e) CXT
f) Tuberculin response
g) IGRA

Answer 7

Sarcoidosis - granulomas. Bottom R = nodule.

(pic)

Question 8

What do the 4 images show?

Answer 8

Top 2: skin sarcoid (colour depends on colour of person)
Bottom 2: uveitis

Question 9

What can you see in these two CXRs?

Answer 9

L: Bilateral hilar lymphadenopathy.
R: pulmonary infiltrates.

NB: locations of different things differ:TB at top of lung, sarcoid at centre, lung fibrosis at bottom.

Question 10

How is saracoidosis diagnosed?

What can you see in these endobronchial US histologies?

How is sarcoidosis treated?

Answer 10

Bloods, 24hr urine, tuberculin skin test, lung function tests, tissue biopsy. (pic)

Sarcoid granuloma (bottom L).

None - monitor lung function and SACE (serum ACE).
Indications for steroids: hypercalcaemia, eye disease, neurological disease, worsening lung function.

Question 11

Case Study

Afghanistan; UK ‘98, TB contact (wife; pleiral TB) 2002, chemoprophylaxis (Heaf 4), cough 3m, fever, wt loss 7kg in 6w, depression.
Exam: well, thin, BCG scar, chest clear
Investigations: FBC: eosinophils 0.5
U+E, LFT: albumin 30mg/L (low - not usually low in sarcoid)
ACE 46 IU/L; CRP 19 mg/L (high, more commonly raised in TB than sarcoid)
Vit D undetectable
Sputum smeal and culture-negative (1/3 of TB pts are culture -ve)

CXR: midzone affected (usually sarcoid) (pic)

Would you think TB or sarcoidosis?

Answer 11

Given RHEZM as previous tx, wt increased by 1kg at 2m (not much), still breathless (not usually part of TB), CXR no response at 2m (TB = should have been), biopsy lung: non-caseating granuloma.

THUS probably sarcoid.

CT showed dots characteristic of sarcoid (top pic). Gave steroids and lungs got abit better (bottom before after pics)