Spinal Metastasis of Unknown Primary Accompanied by Neurologic Deficit or Vertebral Instability

Spinal bone metastases are common. They are mostly localized to the lumbar, thoracic, and cervical spine. The most common primaries to result in spinal metastases include lung, breast, and prostate carcinomas in adults as opposed to leukemia, Ewing sarcoma, rhabdomyosarcoma, and neuroblastoma in children. In patients diagnosed with cancer, bone metastases are found in 40% and spinal metastases in 10%. In this study, we reviewed 25 patients diagnosed with a spinal metastasis of unknown primary who presented with low back pain or acute-onset neurologic deficits and underwent operative treatment.

The retrospective study included 25 patients with a spinal metastasis of unknown primary who presented to our clinic with acute-onset vertebral fracture or neurologic deficit. Statistical descriptions were obtained for each patient. Survival analysis was performed using the Kaplan-Meier method.

The 25 patients included 17 men (68%) and 8 women (32%), with a mean age of 55 years (range, 14-81 years). Eleven patients (44%) presented with varying degrees of motor deficits ranging from flaccid paralysis to paraplegia. Motor deficits were completely reversed in 4 patients postoperatively. The tumors were localized to the upper thoracic spine (T1-4) in 2 patients, in the midthoracic spine (T5-8) in 2 patients, in the lower thoracic spine (T9-12) in 8 patients, in the cervical 7 in 1 patient, and in the lumbar spine in 12 patients. In 10 patients, the tumor affected multiple spinal regions. Nonosseous tumors were not present in 10 patients. Ten patients had an extradural tumor. Costal involvement was detected in 2 patients. The tumors were pathologically identified as lung cancer (n = 3), lymphoma (n = 5), breast cancer (n = 3), gastric cancer (n = 2), liver cancer (n = 2), prostate cancer (n = 2), renal cell carcinoma (n = 2), malignant melanoma (n = 1), plasmacytoma (n = 1), bladder cancer (n = 1), paraganglioma (n = 1), Ewing sarcoma (n = 1), and yolk sac carcinoma (n = 1). Posterior instrumentation was performed in patients with instability. In addition, decompression was performed in patients with neurologic deficit.

Considering that 10% of patients with cancer are diagnosed by vertebral metastasis, presence of malignancy should be suspected and a detailed examination should be performed in patients presenting with vertebral fractures caused by no or minor trauma. Moreover, in patients presenting with neurologic deficit, soft tissue metastases leading to spinal cord compression should be kept in mind and further examinations should be promptly administered.