Diagnosis of the case presented in the previous edition

RADIOLOGICAL DIAGNOSIS

Diagnosis of the case presented in the previous edition

Gustavo Sobreira Taberner; Eduardo Scortegagna Junior; Cleonice Isabela S. Silva; Nestor L. Müller

Department of Diagnostic Imaging, Universidade Federal de São Paulo, Escola Paulista de Medicina and the Radiology Department of Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada

Miliary tuberculosis with tuberculous pericarditis

COMMENTS: Pulmonary tuberculosis (TB) is one of the most serious respiratory infections. The clinical manifestations of TB vary depending on the site affected and immune status of the host, as well as on the number and type of comorbidities. Pulmonary TB is caused by Mycobacterium tuberculosis and is traditionally classified as either primary or secondary (usually referred to as post-primary or reactivation TB). Primary TB typically presents as air-space consolidation, enlarged hilar or mediastinal lymph nodes, pleural effusion and, occasionally, a miliary pattern. The post-primary form is more common in adult patients, resulting from reactivation at the site of a previously acquired infection. The most common manifestations include opacities (linear or nodular) and cavitations, predominantly in the apical and posterior portions of the upper lobes. Pleural effusion and a miliary pattern are less common in the post-primary form.

Miliary TB is caused by the hematogenous dissemination of M. tuberculosis, to which immunocompromised individuals are more susceptible.

Radiographically, miliary TB is characterized by a fine nodular pattern. In 30 to 40% of patients with miliary TB, the nodules are not visible in radiological images, even in retrospect. High-resolution computed tomography (HRCT) can be useful in the diagnosis of miliary TB in patients presenting normal chest X-rays or nonspecific radiographic findings. In HRCT scans, these nodules are well defined, measuring 1 to 3 mm in diameter. The distribution of the nodules is random in relation to the structure of the secondary lobule of the lung, and they may be found in the cephalocaudal or central-peripheral regions. Due to their smaller size and uniformity of diameter, as well as their diffuse distribution throughout the lung, miliary nodules are, in most cases, easily distinguished from the centrilobular nodules found in TB patients presenting bronchial dissemination. Other HRCT findings than can be seen in miliary TB include nodular thickening of the interlobular septa/fissures, nodular irregularity of the blood vessels and areas of ground-glass attenuation.

Pericarditis is a complication that affects pulmonary TB patients at a rate of 1 to 8%, being even rarer in cases of miliary TB. It is believed that pericardial involvement is caused by infected ganglia and the anatomical proximity of the lymph nodes to the pericardial sac. Although a more remote possibility, the pericardium may be affected by hematogenous dissemination of the bacteria.

The tomographic findings most commonly seen in tuberculous pericarditis are pericardial thickening (greater than 3 mm), well-defined pericardium in contrast-enhanced imaging and pericardial effusion, the last of which may or may not be present.

Approximately 10% of patients with tuberculous pericarditis develop constrictive pericarditis. Computed tomography scans of such patients reveal fibrotic thickening and, frequently, pericardial calcification.

REFERENCES

1. Suchet IB, Horwitz TA. CT in tuberculous constrictive pericarditis. J Comput Assist Tomogr 1992;16:391400.

2. Lee KS, Song KS, Lim TH, Kim PN, Kim IY, Lee BH. Adult onset pulmonary tuberculosis: Findings on chest radiographs and CT scan. AJR 1993;160:7528.

3. Gültekin F, Bakicinz, Elaldi Nazif B. Tuberculous pericarditis: A report of three cases. Curr Med Res Opin 2001;17:1425.

4. Webb WR, Müller NL, Naidich DP. High-resolution CT of the Lung, Third Edition. Philadelphia: Lippincott-Raven, 2001.

Readers correctly diagnosing the case presented in the March/April 2004 issue:

Ana Luiza Schneider Moreira - Pavilhão Pereira Filho Sta. Casa de Porto Alegre, Porto Alegre, RS

Bibiana Policena de Oliveira - Universidade Federal de Pelotas, Pelotas, RS

Caio Júlio César dos Santos Fernandes - Universidade de São Paulo, São Paulo, SP

Daniela Toss - Hospital Dia do Pulmão, Blumenau, SC

João Paulo Maciel - Universidade Federal da Bahia, Salvador, BA

Jorge L. Pereira-Silva - Universidade Federal da Bahia, Salvador, BA

Lilian Pinto de Azevedo Oliveira - Samer Hospital, Resende, RJ

Lucia Maria Macedo Ramos - Santa Casa de Misericórdia de Passos, Passos, MG

Luiz Carlos Corrêa da Silva - Pavilhão Pereira Filho Sta. Casa de Porto Alegre, Porto Alegre, RS

Luiz Carlos Pereira Junior - Universidade Federal de Pelotas, Pelotas, RS

Wagner Malheiros - Diagnóstico e Imagem, Juiná, MT

Wilson Assami - Diagnóstico e Imagem, Juiná, MT

Publication Dates

• Publication in this collection
  10 Oct 2005
• Date of issue
  June 2005