Primary spinal primitive neuroectodermal tumor (PNET) of the central nervous system has a low incidence. The intraspinal case is very rare. Around 30 cases have been reported so far 1).
Spinal PNETs, like their cranial counterparts, are aggressive tumors and patients with these tumors typically have short survival times despite maximal surgery, chemotherapy, and radiation. Because no standard management guidelines exist for treating these tumors, a multitude of therapeutic strategies have been employed with varying success 2)
Ma et al. from the Beijing Tiantan Hospital summarized the cases of primary spinal PNET available in the database of the institute, either intramedullary or extramedullary cases. Then they did literature review of the same disease.
There were eight cases of primary spinal PNET available in there database, with one intramedullary case and seven extramedullary cases. Surgical resection was performed. The histology diagnosis was PNET. Peri-operative image examinations of the whole central nervous system (CNS) were performed to exclude tumors other than spinal cord origin. Then during literature review, 33 reports of the disease were included. The pre-operative diagnosis rate was low. The disease had a high recurrence rate and poor prognosis given available treatment 3).
A 14-year-old teenage girl had suffered from progressive left upper back pain with bilateral lower legs weakness and numbness for 1 year. After treatment, left neck mass was noted 3 years later.
Initially, magnetic resonance imaging (MRI) showed neurogenic tumor involving intradural extramedullary space of T5-T10. Pathology report showed PNET (World Health Organization grade IV) featuring lobules of neoplastic cells with round regular nuclei, high nucleus-to-cytoplasm ratio, and fibrillary cytoplasm. At the time of tumor recurrence, chest MRI then showed recurrent tumor at T2-T3 level of the epidural space with right neural foramina invasion. Brain MRI showed extensive bilateral calvarial metastases and leptomeningeal metastases in the right frontoparietal regions. Bone scan showed multiple bone metastases.
T-spine tumor removal and adjuvant radiotherapy (RT) to T-spine tumor bed were performed in the initial treatment. After clinical tumor recurrence, tumor removal was done again. She then received chemotherapy followed by whole brain irradiation with hippocampal sparing with 35 gray in 20 fractions.
After treatment, follow-up images showed that the disease was under control. There was no neurological sequela. She has survived more than 7 years from diagnosis and more than 4 years from recurrence to date 4).
A 5-year-old Moroccan boy, who presented with torticollis for 1 month. Computed tomography scan and Magnetic resonance imaging of the cervical spine revealed an extradural, dumbbell-shaped mass with extra-spinal extension at the left C1-C6 level. Multiple biopsy specimens were obtained. Histological examination revealed a highly cellular neoplasm composed of diffuse sheets of tumor cells having monomorphic, round to oval, finely vesicular nuclei. Immunohistochemical findings confirmed the diagnosis of intraspinal peripheral primitive neuroectodermal tumor.
After this illustrative case, they reviewed the literature on clinicopathological and therapeutic aspects. In practice, it is important to consider the diagnosis of peripheral primitive neuroectodermal tumor in children and adolescents with an apparent soft-tissue mass located in the spine 5).
A 60-year-old female, which presented clinically as an intraspinal tumor, causing symptoms of lower back pain, numbness and pain in the right lower extremity. The patient underwent tumorectomy. Following primary therapy, the symptoms of spinal cord compression were relieved. The patient underwent several courses of radiotherapy following surgery but refused to continue with chemotherapy. After a further four months, the tumors recurred and the patient succumbed to the disease 6).
A two years old female child presented with weakness both lower limbs. Preoperative MRI of the spine and paravertebral regionIso – hyper intense posterior placed extradural lesion, non contrast enhancing from D11-L2 levels with cord compression D9 to L3 laminectomy done. Granulation tissue found from D11 to L2. with cord compression. The granulation tissue removed in toto. The pathological findings were consistent with PNET. Post operative neurological improvement was minimal. Cranial screening ruled out any intracranialtumour. Hence a diagnosis of primary spinal PNET was made. A review of the literature shows that only 19 cases of primary intraspinal PNETs have been reported to date and the present case extradural in location. Primary intraspinal PNETs are rare tumors and carry a poor prognosis 7).
Multimodal therapy of an intramedullary cervical primitive neuroectodermal tumor in an adult. 8).
A 22-year-old woman with history of severe progressive neck pain, without radiation, associated with paresthesia in the right arm, and palpable right posterior cervical mass. Neurological examination showed increased reflexes in all four limbs, bilateral Hoffman’s sign, right Babinski’s sign, and right hemi-hypoesthesia. Neuroimaging revealed a right posterior cervical lesion with heterogeneous contrast enhancement extending to the neural foramina of the atlas and axis. Patient underwent microsurgical removal of the lesion, and histopathological and immunohistochemical analysis confirmed the diagnosis of peripheral primitive PNET (pPNET). The patient had adjuvant treatment with radiotherapy and chemotherapy. After twelve months, neuroimaging showed no signs of tumor regrowth and the patient had no neurological deficits. However, three months later, the patient developed hydrocephalus and cerebrospinal fluid (CSF) was positive for neoplastic cells. No other treatment was administered and the patient died.
pPNET is a rare malignant tumor with poor prognosis, although promising results with multimodal treatment-surgery, radiotherapy, and chemotherapy. Diagnosis requires immunohistochemical analysis, with identification of neuronal differentiation markers 9).
A 18-year-old female with conus intramedullary tumor diagnosed to be primary spinal primitive neuroectodermal tumor following histopathological examination after surgery 10).
A female who presented at age 21 with diffuse involvement of the lower spinal cord. After biopsy and successful treatment with radiation and chemotherapy, she recurred 10 years later with disease in her cerebellum. She was reinduced with chemotherapy and subsequently received high-dose chemotherapy with autologous stem cell support. She is alive and free of disease 11 years after her initial presentation. This represents the longest survival ever documented for a primary spinal PNET 11).
A 15-year-old girl who presented with gradual onset, over 1 month, of upper back pain and bilateral lower leg weakness. A thoracic spine MRI showed a dumbbell-shaped epidural mass at T2-4 with right paraspinal and posterior mediastinal extension. Surgical resection of the epidural tumor for decompression was performed. The pathologic examination revealed a PNET. Primary spinal PNETs typically have a poor prognosis and optimal therapy has not yet been defined. Surgical resection, with the combination of chemo-radiotherapy or radiotherapy, leads to better outcomes. However, primary epidural PNETs may be classified as a subtype of spinal PNETs because they are free from intrathecal invasion. For these patients, surgery alone and surgery combined with radiotherapy or chemo-radiotherapy remain controversial. Our patient received surgery alone and, 1y ear later, has experienced no local recurrence within the epidural space but the mediastinal part of the tumor has enlarged 12).
A 45-year-old man with a peripheral primitive neuroectodermal tumour arising in the cervical spine. Alexander et al., believed this to be the first report of this type of tumour in the cervical spine 13).
A 25-year-old male patient presented with an extremely rare primary spinal peripheral primitive neuroectodermal tumor (pPNET) manifesting as acutely progressive paraparesis and back pain. Neuroimaging and intraoperative examination showed that the tumor was confined to the epidural space of the thoracic spine. The patient was treated successfully by gross total resection of the tumor followed by chemotherapy and local radiotherapy. The present case illustrates the unexpected occurrence and important differential diagnosis of primary epidural pPNET of the thoracic spine in young patients presenting with progressive paraparesis and back pain 14).
A 29-year-old male with a dumbbell-shaped pPNET at the T9-10 spine level, including details of his examination, surgical procedures applied, histological and genetic findings, and his subsequent treatment. They discussed the clinical course, the pathology and treatment for this disease, the surgical approach to thoracic dumbbell tumors and reviewed the literature. This is the first report of a case of a dumbbell-shaped intradural and spinal peripheral PNET 15).
A 54-year-old woman who presented with quadriplegia and bladder and bowel dysfunction. The patient had suffered symptoms of neck pain for 1 month and left shoulder weakness for 10 days. Magnetic resonance imaging of the cervical spine revealed an intramedullary mass extending from C-2 to C-5 with an exophytic component in the adjacent left subarachnoid space. Multiple biopsy specimens were obtained, and a partial excision was performed. Histological examination revealed nodular growth and neuronal differentiation, with a striking resemblance to desmoplastic medulloblastoma. A positron emission tomography scan did not reveal uptake at any site. These findings confirmed the diagnosis of a primary intramedullary PNET. Postoperatively, the patient was given craniospinal radiotherapy with a radiation boost to the tumor bed 16).