Neurosurgery notes/Tumours/Cranial and paraspinal nerve tumours/Cauda equina neuroendocrine tumour

Cauda equina neuroendocrine tumour

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Cranial and paraspinal nerve tumours

General

  • Aka
    • Paraganglioma of the cauda equina
    • Cauda equina paraganglioma
  • Is now recognised as a distinct tumour type from the more common paragangliomas encountered in other sites
    • Due to
        • Differences
        Paragangliomas of the CE/FT
        Head and neck paragangliomas
        DNA methylation
        Hypomethylated M3 cluster → Wnt signalling alterations
        Hypermethylation M1 Cluster → TCA cycle-related genes
        Familial associations
        Lack of
        Present
      • Spinal paragangliomas there is low SDH mutation and are generally non familial
        • If a patient has a single spinal paraganglioma it is not genetical
        • If a patient has multiple spinal paraganglioma OR with other neoplasia (pheochromocytoma, GIST, Renal Ca, Pituitary adenoma, Thyroid Ca) it is genetical

Definition

  • Essential:
    • Well-demarcated tumour with Zellballen architecture AND
    • Synaptophysin or chromogranin immunoreactivity in chief cells AND
    • Cauda equina location AND (for unresolved lesions)
    • Methylation profile of cauda equina neuroendocrine tumour
  • Desirable:
    • S100-positive sustentacular cells
    • Cytokeratin-positive chief cells
    • Reticulin silver stain showing typical architecture

Numbers

  • Most common
  • All Cauda equina neuroendocrine tumours are sporadic
    • In contrast, as many as half of all phaeochromocytomas/paragangliomas outside the CNS in adults, and > 80% of these tumours in children, are inherited
  • In cauda equina and filum terminale
  • Mean 46 yrs
  • Male:female= 1.4:17.1

CNS WHO grading

  • Grade 1

Localisation

  • Cauda equina region
    • Most
    • Entirely intradural
    • Attached either to the
      • Filum terminale or
      • To a caudal nerve root (less often)

Origin

  • Regional autonomic nerves and blood vessels
  • Peripheral neuroblasts normally present in the adult filum terminate undergo paraganglionic differentiation

Pathology

  • Macro
    • Oval to sausage-shaped, delicately encapsulated, soft, red-brown masses that bleed freely;
  • Micro
    • See Paraganglioma (Glomus tumour)
    • Approximately 25% of cauda equina neuroendocrine tumours contain mature ganglion cells and a Schwann cell component (gangliocytic neuroendocrine tumours)

Genetics

  • Cauda equina neuroendocrine tumours are histogenetically and molecularly distinct from paragangliomas and phaeochromocytomas outside the CNS
    • Paraganagliomas and phaemochromocytomas
      • Due to mutations in SDH subunit genes
    • Cauda equina neuroendocrine tumour overexpress the transcription factor HOXB13
      • Which is developmentally expressed in the caudal extent of the spinal cord and in the urogenital sinus.
      • It coincides with dynamic changes associated with the formation of the secondary neural tube

Clinical features

  • Low back pain
  • Sciatica
  • Rare:
    • Paraparesis
    • Sphincter problems (CES)
  • Extremely rare
    • Endocrine secretions
      • Catecholamine hypersecretion
        • HTN
          • Differentiating HTN from pheochromocytoma vs essential HTN
            • Clonidine suppression test
              • Which reduces only essential hypertension
              • Clonidine
                  • Centrally acting α2-agonists (presynaptic) → ↓ central adrenergic outflow
                  Clonidine - Mechanism of Action - YouTube
              • If no decrease in plasma catecolamine levels is detected after giving a 0.3 μg/kg oral test dose the study is considered positive (pheochromocytoma).
        • Palpitations
        • Diaphoresis
        • Headaches
      • Frequently actively secrete neuropeptides, particularly 5-hydroxytryptamine and somatostatin, although symptoms related to this chemical production are usually absent.
    • SAH

Radiology

  • Indistinguishable from that of schwannoma or ependymoma
  • Sharply circumscribed
  • Can be partially cystic
  • Can be Gd enhancing
  • A low signal intensity rim (cap sign) on T2-weighted images can be caused by subcapsular haemosiderin
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sCT
sMRI T1W1
T2W1
C+ (Gd)
Spinal paraganglioma
Common contrast enhancement (due to rich capillary network). Rarely causes changes in the vertebral bone.
Isointense
Hyperintense, hemorrhage is common, leading to a hemosiderin cap sign
Intense enhancement is virtually always seen
Spinal meningioma
Isodense or moderately hyperdense mass hyperostosis may be seen but is not as common as in the intracranial forms, calcification may be present.
Well circumscribed, isointense to slightly hypointense
Isointense to slightly hyperintense
Moderate homogeneous enhancement. Dural tail
Spinal ependymoma
Ependymomas may expand the spinal canal, cause scalloping of the vertebral bodies and extend out of the neural exit foramina.
Usually isointense, hemorrhage and calcification can also lead to regions of hyper or hypointensity
Hyperintense, low intensity may be seen at the tumor margins because of hemorrhage. Calcification may also lead to regions of low T2 signal
Typically homogeneous
Images
T1
T1
T1
T1
T1+C
T1+C
T1+C
T1+C
T2
T2
T2
T2

Treatment

  • Surgical resection is the treatment of choice, sometimes with preoperative embolisation to reduce intra-operative blood loss.

Prognosis

  • Slow-growing
  • Curable by total excision;
    • Post-resection recurrence rate of less than 5%
  • Rare CSF seeding or mets outside of CNS
    • In contrast, 10-20% of paragangliomas outside the CNS have metastatic potential

Differential diagnosis

  • The differential diagnosis is essentially that of other intradural extramedullary tumours, particularly those located in the lumbar region.
    • Myxopapillary ependymoma
    • Neurogenic tumour
    • Spinal schwannoma
    • Spinal neurofibroma
    • Spinal meningioma (rare in the lumbar region)