EXTRAPULMONARY TUBERCULOSIS

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EXTRAPULMONARY TUBERCULOSIS
HamidReza Naderi MD Department of Infectious
Diseases Mashhad University of Medical Sciences
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• 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.

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• 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 smear-positive and also
  present with extrapulmonary tuberculous disease
  manifestations are categorized as pulmonary TB.

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• 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
  HIV-infected 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.

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• 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.

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• 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.

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• 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

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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.
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• 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.

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• 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.

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• 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.

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• 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.

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• 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.

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• 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.

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GENERAL COMMENTS ON TREATMENT OF EXTRAPULMONARY
TUBERCULOSIS
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• 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.

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• 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.