Presentation
Presented for thoracic subcutaneous edema and paresis of the pelvic limbs.
Patient Data
Referral radiographs show increased opacity and widening in the dorsal caudal mediastinum, with lack of visibility of the aorta. There is a partially included cranial mediastinal mass in the region of the sternal or thoracic lymph nodes. On the ventrodorsal projection, there is an additional mass cranial to the left kidney and medial to the spleen.
There is a large 7 cm length by 3 cm height by up to 4 cm width caudal mediastinal mass ventral to T8-T13. This mass is T1W hypointense, T2W predominantly hyperintense, STIR hyperintense, and heterogenously contrast enhancing.This mass is extending through the left T9-10, T10-11, and T11-12 intervertebral foramina into the vertebral canal where it is causing a compressive left sided extradural mass effect from T9 through T12. The spinal cord is deviated predominantly to the right, decreased in diameter, and there is complete loss of the circumferential signal from CSF/epidural fat in this region. Concurrently the mass extends dorsally between the left 9-12 ribs and surrounds the tenth rib. The bone marrow of the surrounded ribs is contrast enhancing.
There is a second lobular 4.5 by 2.9 cm mass medial and slightly cranial to the left kidney. An additional structure consistent with a left adrenal is not identified; however; motion and slice thickness limit evaluation of this area. The right adrenal is identified. There are two additional right retroperitoneal nodules which are STIR hyperintense, T1W hypointense, T2W hyperintense, and heterogeneously contrast enhancing; these are best delineated on the STIR sequence.
There is a contrast enhancing nodule within the ventral aspect of the left epaxial musculature. There is a 3 cm diameter cranial mediastinal mass with similar T1W hypointensity, T2W hyperintensity, and heterogeneous contrast enhancement.
The mass is consistent with neoplasia, especially that of developmental origin (e.g primitive nueroectodermal tumor, neuroblastoma, neuroendocrine neoplasia, round cell neoplasia).
Gross pathology images of the two masses.
Case Discussion
This tumor was classified as a a peripheral, primitive neuroectodermal tumor (pPNET) due to positive immunohistochemical staining to synaptophysin and triple neurofilament protein, Peripheral PNETs are exceptionally rare and aggressive, and in people are represented by the Intraosseous pPNET (Ewing's sarcoma), the extraosseous pPNET, and thoracopulmonary Askin's tumor. This group is separate from the peripheral nervous system PNETs including neuroblastoma, ganglioneuroblastoma, and ganglioneuroma 1. These tumors arise from germinal neuroepithelial cells of the neural crest that normally differentiate into ganglia, the adrenal medulla, skin melanoblasts, and parts of the peripheral nervous system 3. Two similar case reports suggest this tumor location may be associated with ganglia or peripheral nerves 3,4.
On necropsy, the mass was found to be two masses, one invading the epidural space and one adjacent to the left kidney and adrenal gland. No invasion was found into the aorta or spinal cord, and the bone was not examined histologically. The mediastinal mass was comprised of the same neoplasm and suspected to be lymph node metastasis.
Unable to process the form. Check for errors and try again.