August 12, 2009

Solitary Vertebral Metastasis Involving the Spinous Process

Figure 1: Chest radiograph (cropped to the thoraco-lumbar junction) shows absence of a spinous process of the T11 vertebra (arrow) in a patient with known hepatocellular carcinoma.
Figure 2: Sagittal-reformatted CT image shows an enhancing soft tissue mass (arrows) involving the spinous process of T11 with epidural extension, causing narrowing of the central spinal canal.

Facts: Spinal Metastasis
  • Spine is the most common site of bone metastasis
  • 10% - 30% of patients with cancer develop symptomatic spinal metastasis
  • 12% - 20% of malignancies present with spinal metastasis
  • Most spinal metastases are extradural lesions that initially start as osseous lesions in a portion of the vertebra
  • Breast, lung, prostate, hemopoietic (lymphoma, multiple myeloma), and renal tumors are common ones metastasizing to the spine
Diagnosis of Solitary Spinal Metastasis
  • Biopsy is mandatory if the isolated spinal lesion is unknown, even in the face of a distant history of a primary malignancy (because it may represent a new primary)
  • Biopsy may be deferred if there is a known history of metastatic disease with multiple lesions -- new spinal lesion may be treated without the need for further histologic evaluation
  • Imaging-guided (fluoroscopy or CT) biopsy is preferable. Better yield for lytic lesion versus sclerotic lesion.
Treatment Plan
  • To help planning the management, detailed imaging study and description is needed. Isolated spinal tumor may be resected by intralesional excision (piecemeal removal of the tumor), or en bloc resection (removal of tumor mass including a cuff of healthy tissue encasing the tumor).
  • In this regards, it is important to describe lesions as "intracomparmental" (i.e. involving vertebral body only, body with pedicle extension, body with pedicle and lamina extension), "extracompartmental" (i.e. with epidural extension, paravertebral extension, 2-3 vertebrae), or "multiple skip lesions"
Our case - isolated metastatic hepatocellular carcinoma to the posterior element of the thoracic spine.

Donthineni R. Diagnosis and staging of spine tumors. Orthop Clin N Am 2009;40:1-7.

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