Case of the Month May 2014, page 4

Answer: The images show a large, intensely hypermetabolic heterogeneous mediastinal mass, most suggestive of a neoplastic process.  No remote masses or hypermetabolic foci are present.  The most likely possibility is lymphoma, though other possibilities, such as germ cell tumors, thymic carcinoma, or thymoma remain.

The pericardial fluid showed atypical cells, but no other marked abnormalities.  An initial biopsy was non-diagnostic. Patient underwent open biopsy via a Chamberlain procedure by CT surgery.  Pathology showed high-grade liposarcoma.

Discussion

Statistically, the most common mediastinal masses are thymomas, neurogenic tumors, benign cysts, and lymphadenopathy.

A useful initial mnemonic when considering anterior mediastinal masses encompasses the five T’s: thymus, thyroid, thoracic aorta, teratoma (germ cell tumors), and “terrible” lymphoma.

On plain films, signs that localize a lesion to the anterior mediastinum include:

  • An obliterated retrosternal clear space
  • Displaced anterior junction line
  • Obliterated cardiophrenic angles
  • Visualization of the hilar vessels through the mass
  • Effacement of the aortic silhouette
  • Lesions that tend to occupy more than one mediastinal component (such as in this case) include mediastinitis, hematomas, vascular entities (e.g., hemangiomata), liposarcoma, bronchogenic cancer, metastases and lymphangiomas (fluid containing).

The differential for a fat-containing mediastinal mass includes the following:
 

  • Thymolipoma
  • Teratoma (Germ cell tumors)
  • Esophageal lipoma
  • Fat deposition
  • Lipoma
  • Lipoblastoma
  • Liposarcoma
  • Extramedullary hematopoiesis

References

P M Tecce, E K Fishman, and J E Kuhlman. CT evaluation of the anterior mediastinum: spectrum of disease.  RadioGraphics 1994 14:5, 973-990
http://www.radiologyassistant.nl/en/p4620a193b679d/mediastinum-masses.html
 

StatDx

< Previous PageVisit our Case of the Month Archive