Review Question - QID 213126

The finding of an absent unilateral pedicle is referred to as the winking owl sign and represents pedicle destruction from metastatic disease, which would be the most likely cause of a destructive osseous lesion in the spine in adults. The most appropriate next step would be identification of the source of the metastasis.

After the lung and liver, bone is the third most common location for metastatic disease in adults over age 40 years. Primary tumors that are more likely to metastasize to the spine include breast, prostate, lung, renal, and thyroid carcinoma. Even with an identified primary cancer, a second primary cancer must be considered during the workup of a new lesion, as the discovery of new cancer may potentially affect treatment decision-making. For example, preoperative embolization prior to surgical intervention may be considered if a new renal or thyroid carcinoma is diagnosed, whereas a wider-resection may be undertaken for a primary sarcoma of bone.

Rose et al. published a review article on the evaluation and management of metastatic disease in the thoracic and lumbar spine. They stressed the importance of individualization in both diagnostic and therapeutic strategies. They reported three main categories of patients who present with spinal osseous lesions and include patients with known cancer metastatic disease, patients with known cancer without a history of metastatic disease, and patients without prior history of cancer. They concluded that patients in the second and third categories should be properly evaluated with appropriate workup prior to any treatment.

Thiex et al. investigated the role of preoperative transarterial embolization in spinal tumors in a retrospective cohort study. They reported no significant difference in intraoperative blood loss in patients with partial versus complete embolization of their spinal tumor, and that embolization was effective in most cases. They concluded that tumor hypervascularity was not limited to the classically vascular tumors like renal cell carcinoma, and it was observed in some patients with breast and prostate cancer.

Figure A is a lateral radiograph of the lumbosacral spine. Figures B depicts an absent unilateral L1 pedicle referred to as the winking owl sign, which represents pedicle destruction from metastatic disease. Illustration A is a labeled radiograph of the winking owl sign.

Incorrect Answers:
Answer 2: MRI cervical spine is not indicated as the next step as the patient has no neurological deficits, signs of myelopathy, or infectious signs/symptoms to suggest epidural abscess. Identification of the primary malignancy and staging is paramount.
Answer 3: Despite the recent IV drug use, this patient has no signs of infection (afebrile, normal WBC, ESR, CRP).
Answer 4: NSAIDs and physical therapy would be a negligent next step as the patient has a metastatic lesion that needs to be identified.
Answers 5: Identification of the primary malignancy and staging is of paramount importance prior to any surgical intervention.