IS Case 370: Retroperitoneal ganglioneuroma
2009 URMC Imaging Sciences
Publication Date: 2010-03-02
Ultrasonography shows a homogeneous, hypoechoic, well-circumscribed mass to the right of the IVC at the level of the umbilicus. CT scan demonstrates a well-circumscribed 7cm homogeneous retroperitoneal soft tissue mass with attenuation slightly less than muscle. There is subtle delayed enhancement of the mass.
Ganglioneuromas and ganglioneuroblastomas are tumors of the sympathetic nervous system that originate from undifferentiated neural crest cells. Ganglioneuromas are composed of mature ganglion cells without any immature elements, atypia or mitotic figures and are therefore benign tumors. Closely related ganglioneuroblastomas and neuroblastomas are composed of immature neuroblasts and are considered more aggressive and malignant. Ganglioneuromas can grow almost anywhere along the paravertebral sympathetic ganglia or in the adrenal medulla. Most commonly (38% of cases) they occur in the posterior mediastinum with the retroperitoneum being the next most frequent site of involvement. Ganglioneuromas usually occur in adolescents and young adults (mean age 7 years), but have been reported in all age groups. From an imaging standpoint, all neuroblastic tumors ( ganglioneuroblastomas, ganglioneuromas, and neuroblastomas) look similar. The main difference is that ganglioneuroblastomas and neuroblastomas can metastasize and have a more aggressive appearance. Retroperitoneal and adrenal ganglioneuromas appear as a well-defined round or lobulated retroperitoneal mass, which may contain calcifications. The lesions tend to grow around major blood vessels, but not invade or compress the vascular flow. On CT, the typically findings include a homogeneous mass with less attenuation than muscle and delayed heterogeneous uptake of contrast. On MRI, ganglioneuromas have characteristic curvilinear bands of low signal-intensity on T2-weighted images which has been described as a "whorled pattern." Once correctly identified, treatment of a localized ganglioneuroma is surgical excision. Complete surgical resection is important to allow adequate tissue sampling and to ensure the pathologist can exclude the presence of immature or aggressive elements.
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