Case and content by Lauren Brown, MD
Expert radiologist interpretation by David Godwin, MD
Differentiate a mediastinal from intrapulmonary mass.
20 yo woman presents with one week of new left-sided chest and mid-thoracic back pain associated with shortness of breath, chills and non-drenching night sweats. She denies weight change, cough, hemoptysis, or sick contacts.
How do you differentiate a mediastinal mass from an intra-pulmonary mass?
- Extra-pulmonary masses are typically well-defined because they are bordered by the pleura
- Intra-pulmonary masses are typically ill-defined, or spiculated, as they are infiltrating the lung parenchyma.
- This case highlights the importance of a lateral image. The lateral image shows a clear posterior border (in blue) of the mediastinal mass that shows up as an ill-defined mass on the PA image.
- The posterior opacity on the lateral film is a left-sided pleural effusion (blue line). The silhouette of the right diaphragm (green line), which travels from the spine to the chest wall, remains clear, while the left diaphragm is obscured by the effusion.
DIAGNOSIS AND OUTCOME
TAKE HOME POINTS
- Extra-pulmonary masses are typically well-defined because they are bordered by the pleura, while intra-pulmonary masses are typically ill-defined, or spiculated, as they are spreading through the lung parenchyma.
What is your differential for an anterior mediastinal mass?
Traditionally the mnemonic is the 4 T’s:
- Teratoma (or other germ cell tumors)
- Terrible lymphoma