mediastinal paraganglioma

Mediastinal paragangliomas are rare tumors derived from chromaffin cells (neuroectodermal cells) that can arise from two major clusters of sympathetic ganglion cells:

• paravertebral (aortosympathetic paraganglia)
• great vessels of the chest (aortopulmonary paraganglia)
• cardiac (extremely rare; may be located along the epicardium, in the atrial cavity, the interatrial septum or the ventricles) 

For further discussion on clinical presentation and pathology, please refer to the parental article on paragangliomas.

Terminology

Paraganglia are clusters of neuroendocrine cells dispersed throughout the body and closely related to the autonomic nervous system, with either parasympathetic or sympathetic function. The largest cluster of cells is found within the adrenal medulla, with smaller collections in the paravertebral space, and head and neck region. Tumor arising in the paraganglia are called paragangliomas. They are classified by both location and secretory function.

Radiographic features 

CT

Mediastinal paragangliomas are seen in as a mass in a characteristic location in the paraaortic region of the middle mediastinum or paravertebral region of the posterior mediastinum corresponding to major cluster of sympathetic ganglion cells. Uncomplicated mediastinal paragangliomas demonstrate intense contrast enhancement.

MRI

• T1: salt and pepper appearance due to enhancing parenchyma (salt) and signal flow voids of vessels (pepper)
• T2
  • hyperintense 'light bulb' appearance
  • salt and pepper enhancement also seen 
• T1 C+ (Gd): heterogenous prolonged enhancement

Differential diagnosis

Differential diagnosis on CT, based on location and contrast enhencement pattern, includes:

• focal Castleman’s disease (angiofollicular lymph node hyperplasia) 
• mediastinal hemangioma
• hypervascular metastases (e.g. RCC)

Siehe auch:

• Paragangliom