INTRODUCTION
Tuberculosis (TBC) is an airborne communicable disease caused by Mycobacterium tuberculosis,
transmitted by patients with pulmonary TBC.
Infection occurs more commonly in adults (25-39 and 60-75 years old patients).
Population groups with increased risk: immunocompromised individuals (AIDS,
lymphoma,
leukemia),
diabetics patients,
children and the aged,
alcoholics,
the poor,
immigrants from third-world countries,
prisoners,
nursing home residents,
health care workers and the homeless.
Up until the mid 1980s,
there was a steady decline in the prevalence of tuberculosis.
Since that time,
however,
there has been a resurgence of tuberculosis.
His increase has been seen not only in Africa and Asia,
but also in Europe and so TBC remains an important cause of morbidity and mortality worldwide.
This resurgence is due to the acquired immunodeficiency syndrome (AIDS) epidemic and the increasing number of drug-resistant strains of Mycobacterium tuberculosis (Multidrug-resistant Tuberculosis or MDR).
- MDR
MDR tuberculosis is no more infective than normal tuberculosis.
However,
it is a more serious infection,
requiring prolonged administration of more toxic second-line drugs,
associated with higher morbidity and mortality rates.
Patients also remain infectious for a longer period once treatment has been started.
- IMMUNOCOMPROMISED PATIENTS
They have a significantly higher prevalence of tuberculosis than does the general population and are also more likely to be infected with MDR tuberculosis.
The pattern of disease is different in immunocompromised patients,
who have a higher prevalence of extra-pulmonary involvement.
SUBTYPE OF TUBERCULOSIS
Tuberculosis is usually confined clinically to the respiratory system (pulmonary TBC, 80% of cases).
However,
it can affect any organ system (extra-pulmonary TBC),
particularly in immunocompromised individuals.
Pulmonary tuberculosis is classically divided into primary and postprimary (reactivation) tuberculosis.
In extra-pulmonary TBC the more common sites involved are: bones,
genitourinary system and central nervous system. Other sites involved are,
in order of frequency: abdomen,
heart (cardiac TBC),
eye (ocular TBC)
RADIOLOGIST'S ROLE
Tuberculosis demonstrates a variety of clinical and radiologic features depending on the organ site involved and has a known propensity for dissemination from its primary site.
Thus,
tuberculosis can mimic a number of other disease entities,
and it is important to be familiar with the various radiologic features of tuberculosis to ensure early,
accurate diagnosis.
Furthermore,
there is a considerable overlap in the radiologic manifestations of both primary and postprimary pulmonary TBC.
However,
confirming the diagnosis is more important than identifying the subtype,
because this allows initiation of a correct clinical management.