Acute tuberculosis

A c u t e Tu b e rcu l o s i s
David Schlossberg,
KEYWORDS  Tuberculosis  TB  Pneumonia  Pneumonitis  CAP
a,b,c, * MD, FACP

Tuberculosis (TB) can present as an acute process and should be included in the differential diagnosis of community-acquired pneumonia (CAP). It may mimic classic bacterial pneumonia or masquerade as an atypical pneumonia, with nonproductive cough and systemicsymptomatology. This review summarizes the clinical and radiologic manifestations of acute forms of TB, emphasizing risk factors and diagnostic clues. The various presentations of TB reflect its pathogenesis and pathophysiology. Mycobacterium tuberculosis is inhaled from droplet nuclei that are suspended in air. These nuclei contain from one to three organisms, which are then distributed in thewell-ventilated areas of the lung, especially the periphery of the midlung fields, most commonly in the right middle lobe, superior segments of the lower lobes and anterior segments of the upper lobes. Right-sided infection is more common than left. Infection is typically unifocal, although it may be bilateral. Clinical manifestations of the initial infection are characteristically minimal; in fact,most patients are asymptomatic. When symptoms are present, cough and dyspnea are most common, with occasional chest pain, sore throat and systemic complaints of fever and malaise. The most common chest X-ray (CXR) is normal; when present, abnormalities include either peripheral infiltrates or adenopathy or both. The infiltrates are seen in anterior as well as posterior segments, and lower lobes aswell as upper. They may be rounded, ill-defined, or dense, and may be segmental or lobar. Hilar or mediastinal adenopathy are characteristic and reflect the lymphatic circulation, in that left-sided infiltrates may result in bilateral adenopathy, whereas a focus in the right lung causes adenopathy only on the right. As with various etiologies of atypical pneumonia, the CXR findings are frequentlymore dramatic than symptoms would predict. Pleural effusions are common in primary TB and may exist without corresponding parenchymal infiltrates or adenopathy. Lymph nodes draining the parenchymal focus of primary infection may enlarge and obstruct bronchi either by direct compression or by caseation and rupture through the

Temple University School of Medicine, Philadelphia, PA, USA Universityof Pennsylvania School of Medicine, Philadelphia, PA, USA c Tuberculosis Control Program, Philadelphia Department of Public Health, 500 South Broad Street, Philadelphia, PA 19146, USA * Tuberculosis Control Program, Philadelphia Department of Public Health, 500 South Broad Street, Philadelphia, PA 19146. E-mail address: dschloss@ix.netcom.com
b

a

Infect Dis Clin N Am 24 (2010) 139–146doi:10.1016/j.idc.2009.10.009 0891-5520/10/$ – see front matter ª 2010 Elsevier Inc. All rights reserved.

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Schlossberg

bronchial wall; in such cases, obstructive emphysema or atelectasis my complicate or even dominate the clinical presentation, sometimes referred to as epituberculosis. Erythema nodosum has also been described. This primary focus usually heals, withscarring and calcification of the peripheral parenchymal focus and the draining lymph nodes; together, these two remnants of the primary infection are called the Gohn complex or Ranke complex. If, instead of healing, the initial infection progresses (progressive primary), cavitation and bronchogenic spread may occur as part of the initial infection; infants younger than 5 are at particular risk forlocal progression as well as miliary dissemination. From age 5 to puberty there is a period of relative resistance to such progression, with a return of increased susceptibility in adolescents and young adults. Thus, in adolescents and young adults, primary TB spans a spectrum that includes asymptomatic infection, typical childhood pattern of lower lung field infiltrate with regional adenopathy,...