Tuberculosis Flashcards
Why are children less likely to spread TB?
- Because they rarely develop lung cavities or sputum meat positive TB
- but children above 10 years usually develop adult TB
What is the primary peripheral lesion that occurs as a result of the exudation of polymorphonuclear leucocytes followed by monocytes?
A ghon focus
What is a ghon complex/ ranke’s complex?
It is the ghon focus and the involvement of regional lymph nodes
What are Simon’s foci?
They are small metastatic foci which contain low numbers of mycobacterium and may calcify and are also seen on chest X-ray
In children when is the most risk of developing TB?
-First year after infection especially if with impaired immunity and between <2-3 years
What usually happens aa couple of weeks after the initial infection?
Fever may occur
Enlargement of regional lymph nodes
Hypersensitivity phenomena like erythema nodosum
The TST> 15mm
The disease process goes no further than this
What usually tends to occur in the first 3-9 months following infection?
If they have miliary(disseminated TB) they present with TB-meningitis, lymphobronchial TB and pleural effusions
What age is the safest at getting TB?
5-10 years
What do >10 years usually present with?
TB cavitation in the upper apices similar to adults and pleural effusions
What is IRIS?
TB associated with immune reconstitution inflammatory syndrome which usually occurs with HIV positive children in the first few weeks/months after ARV treatment has been initiated
-accompanied by viral suppression and increase in CD4 count
How does Tuberculosis associated with immune reconstitution inflammatory syndrome present?
It commonly occurs as right sided axillary adenitis due to BCG vaccination given at birth
What is infection without disease?
- incubation phase
- positive TST
- usually a symptomatic children with a normal chest x-ray but at a risk of developing the active disease
What is intrathoracic lymphadenopathy?
It usually occurs after recent infection with Tb
- most children do not have constitutional symptoms but may present with hilar or paratracheal lymphadenopathy and so must be treated with TB drugs to prevent possible further progression of the disease
- we should also always think of a lymphoma
When does a ghon focus show up on chest X-ray?
When it has calcified
What is lymphobronchil Tb?
TB that involves the intrathoracic lymph nodes close the large airways
-this can cause collapse of the airway due to obstruction
If a lymph node ulcerated and the contents are released into the bronchus what can we expect to happen?
Hypersensitivity reaction in the s affected lobe or segment
-usually seen as collapse or consolidation on X-ray
How long does it take for lymphobronchial TB to be treated and for it to resolve?
2-3 months
What kind of pleural effusion can we expect to see in young children? <5 years
Small effusion or thickening of the pleura is seen with the primary focus
What kind of pleural effusion can we expect in older children?
Straw colored, large exudative and lymphocytic effusions are more common and represent pleural hyper-reactivity response
Who is most affected by miliary(disseminated) TB?
- Very young
- malnourished kids
- HIV
What do children with miliary usually present with?
- Wasting
- Hepatosplenomegaly
- Generalised lymphadenopathy
- On auscultation-fine crepitations may be heard
What symptoms in children would suggest miliary TB?
- Fever
- Poor feeding
- Lethargy
What do we see on chest X-ray in miliary TB?
-snowstorm appearance of the diffuse reticulonodular (miliary) pattern throughout the lung fields is highly suggestive of miliary TB
What else presents similarly to the snow storm appearance of miliary TB on X-ray?
Lymphocytic interstitial pneumonitis which occurs in HIV, histoplasmosis, sarcoidosis
What is the rich focus?
It is a foci that allows entry into the blood brain barrier and the CSF that has TB bacilli
-these will undergo cassation and release their contents into the CSF and takes up to 3 months
How long does TBM usually take to show up after primary infection?
3-6 months
Why is the CSF thick and proteinaceous?
-the bacilli and antigen inflammatory response can cause the thick exudate covering the base of the brain and enveloping the cranial nerves and blood vessels and obstructs the CSF flow
What do 80% of children with TBM usually present with?
Obstructive hydrocephalus (communicating or non communicating)
What does the obstructive hydrocephalus cause?
Increased intracranial pressure and may cause cranial nerve palsy
What should we worry about if the child also has vasculitis of the cerebral blood vessels?
Strokes(brain infarcts)
What does TBM initially present with?
- Irritability
- Headache
- Vomiting
How can we stage TBM?
Refined British MRC staging
What is stage 1 oft TBM?
- GCS: 15/15
- No focal neurological fallout
- alert and awake
What is stage 2a?
-GCS: 15/15 with focal neurological deficit
Or GCS: 13-14/15 without focal neurological deficit
What is stage 2b?
-GCS 10-12/15 with or without focal neurological deficit
What is stage 3?
-GCS: less than 10/15 with or without focal neurological deficit
When should we start TBM treatment?
IMMEDIATELY
DO NOT WAIT FOR SPECIAL INVESTIGATIONS
What do we see on chest X-ray of children with TBM?
70-80 have features of primary TB
What would see in CT or MRI scan of the child?
- infractions particularly of the middle cerebral artery
- hydrocephalus
- tuberculoma
What do we usually see on CSF in TBM?
- We usually see a cell count that is low (500x10 to the power of 6/l) with a predominance of lymphocytes
- glucose is low(<2,2mmol/l)
- protein: > 1,2g/l
What is the clinical feature of TBM that we observe on CSF compared to other causes of meningitis?
The CSF values remain abnormal for a long time (for a couple weeks) meaning we should complete TBM treatment
Which lymph nodes are usually involved in children?
- Cervical lymph nodes mostly
2. Inguinal and axillary occassionally
How do the diseased lymph nodes usually feel?
-painless
-matted
-firm
Due to significant periadenitis and fibrosis
How can we diagnose superficial lymphadenitis in TB in children?
We can take a fine needle aspiration biopsy
What would be on our differential diagnosis for superficial lymphadenitis?
- malignancies especially lymphoma
- acute pyogenic infections
- chronic fungal infection
How does abdominal usually occur?
From haematogenous and lymphogenic spread
What are the 4 clinical forms of abdominal TB?
- Intestinal TB-mostly terminal ileum and caecum but any part of the gastrointestinal-intestinal tract may be involved
- Abdominal lymphadenopathy
- Peritoneal disease
- Solid organ TB(liver, spleen)
What are the most common symptoms of abdominal TB?
- Abdominal distension
- Fever
- Loss of weight
- Diarrhea
- Abdominal pain
What do you usually feel on deep palpating in abdominal TB?
- Acute abdomen due to perforation
- Masses-enlarged lymph nodes, matted mesenteric and mental clumping in the RIF, centrally or along both sides of the spine
- Massive ascites
What does compression of the inferior vena cava cause?
Oedema of the lower limbs
What is the differential diagnosis for abdominal TB?
- Lymphoma for abdominal masses
- Malabsorption
- Ascites
- Blood in stools
- Protein losing enteropathy(PLE)
What diagnostic tests can we do to do to diagnose TB of the abdomen?
- Abdominal ultrasound and CT
2. Laparoscopic biopsy might be needed for definitive diagnosis
How does TB usually present in the liver?
Either as a isolated tuberculoma on the liver (hepatic nodule)
How does tuberculous pericarditis present in these children?
- Pericardial friction rub
- Increased cardiac dullness
- Impalpable apex beat
- Muffled heart sounds
How does tuberculous pericarditis occur?
- usually from haematogenous and lymphatic spread
- this then leads to pericarditis with effusion and long term constriction of the heart due to the calcification of the pericardium
What can we do to diagnose TB pericarditis?
- pericardiocentesis-may help with a definitive diagnosis and cans be therapeutic
- we can also do a chest X-ray and echocardiograph
What upper respiratory tract involvement can we expect to see?
- Tonsils asymmetrically enlarged and red and with small yellow nodules and shallow grey ulcers
- Submandibular lymph node swelling may also be seen
What involvement of the eyes would we be able to see in TB in children?
- the everted eyelid reveals thickened granulation with yellow areas
- pre-auricular and tonsillar nodes are enlarged
What is the presentation we can expect in TB of the ear?
- ottorhea (chronic painless discharge)
- facial nerve palsy
- conductive hearing loss
What is the skin involvement in TB?
- Tuberculous wart or chancre
- haematogenous spread may lead to modular lesions, papulonerctotic tubercuilids
What is the bone and joint involvement of TB in children?
- Vertebral involvement(Pott’s disease) is the most common
2. Disease of weight bearing joints(hips and knees)
What is the differential diagnosis for bone and joint involvement in TB?
- Sickle cell anaemia
- Syphillis
- Salmonella
What are the blood abnormalities we can see in TB?
- Normocytic, normochromic anaemia
- Aplastic anaemia
- Pancytopenia
- Neutrophil leucocytosis
Similar to the picture of leukemia
What does TB look like when involving the urogenital system?
- Sterile pyuria should point to TB immediately
How do neonates presenting with TB from the mother present?
- They usually have intra-uterine growth retardation
- Prematurity
- Respiratory disease
What are the three definitive clinical signs that lead to the diagnosis of TB?
- Failure to thrive or weight loss
- Persistent cough or wheeze >2 weeks
- Unusual fatigue(reduced playfulness)
- Prolonged unexplained fever
- Organomegaly or lymphadenopathy
- Lethargic or altered level of conscious
What would indicate a positive turberculin/mantoux test?
- > 10mm
In HIV positive children what would point to a positive TST/Mantoux test?
> 5mm
How long should we wait before we check the result of Mantoux test?
48-72 hours
What are the possible causes of a false positive Mantoux test?
- Incorrect technique
- Immune compromised of any origin
- HIV
- measles
- steroid use
What is the IGRA test?
- used to diagnose TB
- however just shows infection and not disease
- interferon gamma release assays
Where can we get the M.tb organism?
Pus, CSF, bone marrow, pleural and ascetic fluids
Why is difficult for us to get sputum from children?
They swallow sputum and so early morning gastric aspirated or induced sputum collections may be necessary
Why is difficult to do a culture in children?
They are paucibacillary which means that they are often negative
How does the BCG vaccine work?
It prevents disseminated TB in 60-70% early in childhood
