Schwannoma, Lumbar Paraspinal

H&P

• PMHx: NF1
• PSHx: right AKA
• HPI:
  • Presented to neurosurgery clinic
  • Back pain radiating down RLE to the stump x7m
• PE: GCS 15, full strength, RLE amputated at hip, 1+ reflexes, stable walking with crutches

Imaging

Pelvic MRI without Contrast - Axial T1WI, Axial T2WI, Coronal T1WI, Coronal T2WI

Pelvic MRI T1WI with Contrast - Axial and Coronal

Enhancing right L3-4 and L5-S1 paraspinal lesions consistent with neurofibromas with slight extension into the distal neural foramen but no significant extension into the spinal canal.

PET CT

• 42 mCi F-18 FDG IV
• Mildly hypermetabolic well-circumscribed low density right paraspinal mass measuring 7.3 x 6.8 cm most suggestive of a neurogenic tumor, likely neurofibroma given patient's clinical history.

Differential Diagnosis

• Benign
  • Neuroma
  • Neurofibroma
  • Schwannoma
  • Perineurioma
• Malignant Peripheral Nerve Sheath Tumors

Surgical Intervention

• Approach: anterior trans-abdominal
• Multidisciplinary operation
  • Vascular surgery - exposure and closure
  • Neurosurgery - tumor resection
• Forwent intraoperative neuro-monitoring due to patient's right AKA
• Intraoperative frozen: nerve sheath tumor, favors Schwannoma

Intraoperative Imaging

Supine position with lower thoracic and abdominal areas exposed.

A right curvilinear incision was proposed and marked.

The tumor was exposed with several nerves draping over the capsule.

Gross specimen of the tumor

Tumor cavity within the capsule.

Tumor capsule was preserved, as well as the nerves attached to it.

The wound was closed with Dermabond.

Post-Op Course

• Recovered well neurologically
• Resolved back and radiating pain
• Hgb dropped to 7 and required RBC transfusion
• Urinary retention required replacement of Foley
• Pathology:
  • Frozen: favored schwannoma
  • Permanent: schwannoma
    • +S-100
    • +CD34
    • -calretinin
    • +Antoni A and B
    • Nerve sheath tumor, benign

Discussion

Surgical Techniques

Benign Schwannomas and neurofibromas have different techniques because of different patterns of fascicular involvement.

Schwannoma

• Intraoperative monitoring^[1]
• Grows extrinsic to its parent fascicles
• Well-defined capsule - perineurium and nerve bundles
• Enucleation^[2]