From the Guidelines
Yes, pneumonia can cause mediastinal lymphadenopathy. When the lungs become infected during pneumonia, the immune system responds by activating lymph nodes in the mediastinum, causing them to enlarge 1. This lymphadenopathy is particularly common in certain types of pneumonia, such as those caused by tuberculosis, fungal infections, atypical bacterial infections, and some viral pneumonias.
Key Points to Consider
- The size of the lymph nodes is an important factor, with nodes greater than 1 cm in short axis being associated with various diseases, including pneumonia 1.
- The texture and density of the lymph nodes, as well as the presence of fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) activity on PET/CT examination, can also provide clues about the underlying cause 1.
- Clinical history and pulmonary findings are crucial in determining the management of lymph nodes 1.
- A short-axis size threshold of 15 mm can guide the decision process for further evaluation or follow-up 1.
Management and Treatment
- Mediastinal lymphadenopathy typically resolves as the pneumonia is treated with appropriate antibiotics or antifungals 1.
- Persistent lymphadenopathy after treatment may warrant further investigation to rule out other conditions like malignancy 1.
- Imaging studies such as chest CT scans are often used to evaluate the extent of both the pneumonia and associated lymphadenopathy 1.
From the Research
Pneumonia and Mediastinal Lymphadenopathy
- Pneumonia can cause mediastinal lymphadenopathy, as evidenced by several studies 2, 3, 4, 5.
- A study published in 2018 found that pneumococcal pneumonia with bacteremia is associated with mild mediastinal lymph node enlargement, with a mean size of the largest mediastinal lymph node of 0.99 cm 3.
- Another study published in 2017 reported a case of adult community-acquired pneumonia with unusually enlarged mediastinal lymph nodes, which were ameliorated to their normal size following antimicrobial treatment 4.
- A study published in 2000 found that mediastinal lymphadenopathy is commonly associated with parapneumonic effusion, with a mean size of enlarged nodes of 1.4 cm 5.
- The presence of marked mediastinal lymphadenopathy (short axis LN size > 2 cm) should not be assumed to be caused by pneumococcal pneumonia, as other pathologies may be responsible 3.
Characteristics of Mediastinal Lymphadenopathy in Pneumonia
- The degree of lymph node enlargement in pneumonia is typically moderate, with a mean size of 0.99-1.4 cm 3, 5.
- The right paratracheal area is most commonly involved, and the subcarinal area may contain the largest nodes 5.
- Multiple sites may be involved, with a mean number of enlarged nodes of 1.9 5.
- The presence of enlarged nodes does not correlate with biochemical and microbiological stage of pleural infection, length of history, or extent of consolidation 5.