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EXTRAPULMONARY
TUBERCULOSIS
HamidReza Naderi MD
Department of Infectious Diseases
Mashhad University of Medical Sciences
Extrapulmonary TB, like pulmonary TB, is the
result of infection with organisms of the
Mycobacterium tuberculosis complex, which
include M. tuberculosis, Mycobacterium
bovis or Mycobacterium africanum.
Extrapulmonary TB is defined as disease
involving structures other than lung
parenchyma and is less common than
pulmonary TB.
Extrapulmonary tuberculous disease occurs as
result of contiguous spread of tubercle
organisms to adjoining structures, such as
pleura or pericardium, or by
lymphohaematogenous spread during
primary or chronic infection.
According to the World Health Organization
(WHO) patients who are sputum smearpositive and also present with
extrapulmonary tuberculous disease
manifestations are categorized as pulmonary
TB.
Extrapulmonary TB may occur in multiple sites, with
relative frequencies of 42% for lymphatic, 18% for
pleural, 12% for bone or joint, 6% for genitourinary, 6%
for meningeal, 5% for peritoneal, and 11% for other
sites.
The lymph nodes are the most common site of
extrapulmonary TB for both otherwise normal and HIVinfected patients.
Involvement of the meninges is more common in young
children than in other age groups (present in
approximately 4% of children with TB), and the
incidence of TB in the remainder of the extrapulmonary
sites increases with age.
• Lymphadenitis
• Tuberculous lymphadenitis (scrofula) is the most
common form of extrapulmonary TB.
• The diagnosis of scrofula usually is made by fine
needle aspiration of an affected lymph node.
Although AFB smears are positive in only
approximately 20% of cases, granulomatous
inflammation may be obvious.
• Overall, fine needle aspiration has a sensitivity of 77%
and specificity of 93% for TB infection.
• Pleural Effusion
• Pleural extrapulmonary TB may occur early
after primary infection with MTB and manifest
as pleurisy with effusion, or more rarely, it may
occur late in postprimary cavitary disease and
arise as an empyema.
• Tuberculous pleural involvement often causes
no symptoms and resolves spontaneously;
however, in untreated patients, a 65% relapse
rate has been reported, with development of
active pulmonary or extrapulmonary TB within
5 years.
The diagnosis usually is confirmed by •
microscopic and chemical examination of
pleural fluid or pleural biopsy.
White blood cell counts usually range from 500 •
to 2500 cells/mL. The fluid is an exudate with
protein usually exceeding 50% of the serum
protein, and the glucose may be normal to low.
Because there are few bacilli, AFB smears rarely
are positive, and cultures grow MTB for only 25
to 30% of patients.
Pleural biopsy can confirm the diagnosis in •
approximately 75% of patients.
• Bone and Joint Infection
Bone and joint TB remains a disease of older children
and young adults in developing countries.
Skeletal TB presumably develops from reactivation of
dormant tubercles originally seeded during stage 2 of
the primary infection or, in the case of spinal TB, from
contiguous spread from paravertebral lymph nodes to
the vertebrae.
Generally, spinal TB (Pott's disease) accounts for 50 to
70% of the reported cases; the hip or knee is involved
in 15 to 20% of cases, and the ankle, elbow, wrists,
shoulders, and other bones and joints account for 15
to 20% of cases.
• Paraspinal “cold” abscesses develop in 50% or more
of cases, with occasional formation of sinus tracts.
• The so-called skip lesions can easily be missed in
imaging the spine for Pott's disease.
• The main complication of Pott's disease is spinal
cord compression.
• Medical management includes chemotherapy,
modified bedrest, and early ambulation and results
in improvement in approximately 90% of patients
without neurologic involvement.
• Surgical treatment usually is reserved for patients
with neurologic complications.
• Central Nervous System Disease
• Approximately 6% of all cases of
extrapulmonary TB involve the central
nervous system (CNS).
• The peak incidence of CNS TB is in newborn
to 4-year-old children.
• Tuberculous meningitis usually results from
the rupture of a subependymal tubercle into
the subarachnoid space, rather than from
direct hematogenous seeding of the CNS.
• Gastrointestinal Disease
• Gastrointestinal TB infection usually is secondary to
hematogenous or lymphatic spread but also may
result from swallowed bronchial secretions or direct
spread from local sites, such as lymph nodes or
fallopian tubes.
• TB may occur in any gastrointestinal location from
the mouth to the anus, but lesions proximal to the
terminal ileum are rare.
• The ileocecal area is the most common site of
involvement, producing signs and symptoms of
pain, anorexia, diarrhea, obstruction, hemorrhage,
and often a palpable mass.
• The most common clinical manifestations of
gastrointestinal TB are abdominal pain, fever,
weight loss, anorexia, nausea, vomiting, and
diarrhea.
• Approximately 12 to 16% of cases present as an
acute abdomen.
• The signs and symptoms can be so similar to those
of other diseases that the diagnosis often is made
at surgery.
• The clinical manifestations of anal TB include
fissures, fistulas, and perirectal abscesses.
• Peritonitis
• Tuberculous peritonitis may develop from local
spread of MTB infection from a tuberculous lymph
node, intestinal focus, or infected fallopian tube.
• In addition, peritonitis can develop from seeding of
the peritoneum in miliary TB or from the
reactivation of a latent focus.
• The patient commonly has pain and abdominal
swelling associated with fever, anorexia, and weight
loss.
Paracentesis is essential for diagnosis.
The peritoneal fluid is exudative, with a cell
count of 500 to 2000 cells per mL.
Lymphocytes usually predominate, with rare
exceptions early in the process, when
polymorphonuclear leukocytes may
predominate.
AFB smears of the fluid have a low diagnostic
yield, with a reported sensitivity of no more
than 7%, and the culture result is positive in
only 25% of the cases. Peritoneal biopsy
often is necessary to confirm the diagnosis.
GENERAL COMMENTS ON
TREATMENT OF EXTRAPULMONARY
TUBERCULOSIS
• Extrapulmonary foci usually respond to treatment
more rapidly than does cavitary pulmonary
tuberculosis due to the lower burden of organisms
in the former.
• Therapy with four-drug regimens (INH, RMP, PZA,
and EMB) for 2 months, followed by INH and RMP
for 4 months, is advised in most cases caused by
drug-sensitive organisms. The exceptions include
bone and joint disease (6 to 9 months), and
tuberculous meningitis (9 to 12 months though
optimal duration unknown).
• Adjunctive corticosteroids are recommended for
persons with pericardial or central nervous system
(CNS) tuberculosis.
In lymph node TB, the most common form of •
extrapulmonary TB, the affected nodes may enlarge
while patients are receiving appropriate therapy
and even after completion of therapy without
evidence of bacteriological relapse.
For large lymph nodes that are fluctuant and appear •
to be about to drain spontaneously, aspiration
(traverse through normal skin) or incision and
drainage appears to be beneficial.