Primary well differentiated neuroendocrine tumor of the filum terminale. Case report and literature review. / Tumor neuroendocrino bien diferenciado intradural-extramedular primario del filum terminale. Presentación de un caso y revisión de la literatura.

OBJECTIVE: To present a case of a well-differentiated primary intradural-extramedullary neuroendocrine tumor of the filum terminale and to conduct a literature review. CASE: A 68-years old patient was assessed after presenting lower back pain and sciatica with ineffective pain relief. The patient presented an intradural-extramedullary lumbar lesion arising from the filum terminale, which was partially resected. The pathology diagnosis was a well-differentiated primary neuroendocrine tumor (carcinoid tumor). After a multidisciplinary evaluation, fractionated stereotactic radiotherapy was administered. No progression or metastatic spread was observed in successive assessments. DISCUSSION: Neuroendocrine tumors are heterogeneous neoplasms derived predominantly from enterochromaffin cells, in which chemotherapy plays a very limited role. In contrast, radiotherapy has been described in partially resected lesions. CONCLUSION: Well-differentiated primary neuroendocrine tumors with intradural-extramedullary lumbosacral location are an exceptional rarity. Isolated surgical resection, or associated with an adjuvant radiotherapy treatment in subtotal resections, could be considered an effective therapeutic strategy.