Mediastinal Masses

Today we discussed a case of a young woman who presented with dyspnea and was found to have a large mediastinal mass. This ended up being a poorly differentiated carcinoma (of unknown primary) complicated by pericarditis with associated echocardiographic evidence of tamponade, severe left PA artery compression, and post-obstructive pneumonia. She ultimately required pericardiocentesis with extended catheter drainage and was started on palliative chemo-radiation, but expired after several days.  

We discussed a systematic review (Virk in Heart BMJ) about percutaneous interventions for malignant pericardial effusions. Isolated pericardiocentesis demonstrated a pooled recurrence rate of 38.3%. Pooled recurrence rates for extended catheter drainage, pericardial sclerosis and percutaneous balloon pericardotomy were 12.1%, 10.8% and 10.3%, respectively.

A common approach to the differential for mediastinal masses is by compartment (most common in each category in bold):  

Anterosuperior compartment (~60% malignant; the 5 terrible Ts):

  • Thymus: thymoma, thymic cyst, hyperplasia, carcinoma
  • Thyroid: particularly substernal goiter, ectopic thyroid tissue, also parathyroid adenoma
  • Terrible Lymphoma
  • Teratoma and germ cell tumor (including seminoma, yolk sac tumor, embryonal carcinoma, choriocarcinoma)
  • Tissues, other: hemangioma, lipoma, liposarcoma, fibroma, fibrosarcoma

Middle compartment (~30% malignant):

  • Vascular masses/enlargement
  • Esophageal tumors
  • Lymphadenopathy: lymphoma, metastatic lung cancer, sarcoid, infections, Castleman disease
  • Cysts: bronchogenic, pericardial

Posterior Compartment (~20% malignant; spine and neuro):

  • Neurogenic tumors: neurofibroma, neurosarcoma, ganglioneuroma, neuroblastoma, chemodectoma, pheochromocytoma
  • Meningoceles
  • Thoracic spine lesions (Potts for example)
  • Descending thoracic aortic aneurysm