CLINICAL NOTES: Mediastinal mass. Paravertebral.
MACROSCOPIC DESCRIPTION: "Mediastinal mass": Well circumscribed soft grey tissue, 160g, 120x65x45mm. One surface partly lined by shiny membranous pleura over an area 110x70mm. Opposite surface roughened, inked black. Bisected to reveal rubbery soft solid grey tissue with vague nodularity and septa. No areas of necrosis or haemorrhage seen.
MICROSCOPIC DESCRIPTION: Sections show a well demarcated, unencapsulated tumour composed of a proliferation of loosely arranged spindle cells with undulating nuclei and scattered single cells and groups of ganglion cells. The ganglion cells have abundant, amphophilic cytoplasm, large eccentric nuclei and prominent nucleoli. There is a mild patchy lymphocytic infiltrate, scattered adipocytes and occasional psammomatous calcifications. Mitoses are rare. Immature neural elements, haemorrhage and necrosis are not seen. The tumour is 0.4mm from the resection margin but appears completely excised.
DIAGNOSIS: Mediastinal mass: Ganglioneuroma. Completely excised.
Paraspinal ganglioneuromas are extremely rare benign tumours.
Like neuroblastomas and ganglioneuroblastomas, ganglioneuromas are derived from the primordial neural crest cells that form the sympathetic nervous system.
Ganglioneuromas most commonly arise in the paravertebral sympathetic chains of the posterior mediastinum (41.5%) or retroperitoneum (37.5%). Less common sites include the adrenal gland (21%) and neck (8%). Paravertebral ganglioneuromas frequently extend through the neural foramina to involve the epidural space of the spinal canal.
The differential diagnosis for a posterior mediastinal mass is broad and includes:
- neurogenic tumours
- malignant peripheral nerve sheath tumour
- neuroblastic tumours
- non-neurogenic tumours
- paraspinal abscess
- descending aortic aneurysm
- oesophageal neoplasm
- hiatus hernia
- Bochdalek hernia
- lymphadenopathy or lymphoma
- extramedullary haematopoiesis
- foregut duplication cysts
- neurenteric cyst
- oesophageal duplication cyst
- thoracic meningocoele