Assessment of Mediastinal Lymph Node Size in Pneumococcal Pneumonia with Bacteremia
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The significance of mediastinal lymphadenopathy in bacterial pneumonia is unclear.
We performed a retrospective analysis of mediastinal lymph node size determined by chest CT in patients with bacteremic pneumococcal pneumonia. All patients who had positive blood cultures for streptococcus pneumonia over an 11-year period and had a chest CT scan (index CT) within 2 weeks of the positive blood culture were included in the study. Two thoracic radiologists and one pulmonologist independently examined the index CT plus any chest CT scans performed prior (pre-CT) or after (post-CT) the bacteremic episode.
The study cohort of 49 patients was 57% male, 65% White, with mean age of 53 (SD = 20) years. Mediastinal lymphadenopathy was detected in 25/49 (51%) of the cases. The mean size of the largest mediastinal lymph node in short axis was 0.99 (SD = 0.71), ranging from 0.0 to 2.05 cm. There was no correlation noted between the number of lobes involved with pneumonia, and the size of the largest mediastinal lymph node (p = 0.33) or the number of pathologically enlarged mediastinal lymph nodes (p = 0.08). There was a statistically significant increase in the mean size of the largest lymph node between the pre-CT and index-CT group (p = 0.02), and decrease between the index-CT group and the post-CT (p = 0.03).
Pneumococcal pneumonia with bacteremia is associated with mild mediastinal lymph node enlargement. The presence of marked mediastinal lymphadenopathy (short axis LN size > 2 cm) should not be assumed from pneumococcal pneumonia.
KeywordsBacteremia Computed tomography Mediastinal lymphadenopathy Pneumonia Streptococcus pneumoniae
MAJ is the guarantor of the paper, and takes responsibility for the integrity of the work as a whole, from inception to published article. All authors were involved in the study design. SC, AM, HC, NR, performed the data collection and data entry. Two radiologists, JF and FJH, interpreted the CT scan reports. RY performed the statistical analysis. All authors contributed to the writing of the manuscript.
Compliance with Ethical Standards
Conflicts of interest
MAJ consultant for Janssen, Celgene, Questcor, Mistubishi-Tanabe, Novartis. AC, SC, AM, HC, NR, JH, FJH declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee. The Institutional Review Board of Albany Medical College approved this study
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