Schmorl's Node Mimicking Spinal Metastatic Disease: A Case Report and Review of the Literature.

In this report, we present a progressively enlarging, degenerative, intraspongious/intravertebral herniated nucleus pulposus, also referred to as a "Schmorl's node," in a 65-year-old patient with a history of prostate cancer. The patient initially presented to our orthopedic oncology clinic for the evaluation of lytic-appearing lesions involving the L4 and L5 vertebral bodies. He had been diagnosed with prostate cancer approximately four years prior and had been previously treated with prostatectomy. During evaluation for symptoms of neurogenic claudication, computed tomography (CT) demonstrated a hypodense lesion in the L5 vertebral body, which demonstrated mildly increased uptake in the left side of L5 on technetium pyrophosphate nuclear scintigraphy and 18 fluorine fluorodeoxyglucose positron emission tomography-CT scan. CT-guided fine-needle aspiration (FNA) of the lesion was performed and demonstrated no neoplastic findings. He underwent an L4-L5 microscopic unilateral laminotomy with bilateral decompression. However, his neurogenic claudication gradually returned, and he presented to his spine surgeon for further evaluation. Repeat CT of the lumbar spine demonstrated marked interval expansion of the erosive L5 lesion with poorly defined margins as well as a hypodense, erosive lesion in the left side of L4. The patient underwent a repeat FNA, along with a CT-guided core needle biopsy of the lesion at the outside facility which yielded a non-diagnostic specimen. After an extensive discussion with the patient, the decision was ultimately made to proceed with an open biopsy of the L5 lesion with partial L5 corpectomy via left-sided transpedicular approach and L4-S1 decompression and instrumented posterolateral spinal fusion. The primary purpose of the operation was to remove material from the lesion, directly visualize it, and have ample tissue for histopathological analysis. Based on these intraoperative findings and subsequent final histopathologic evaluation, the lesion was definitively diagnosed as a large, aggressive, intraspongious/intravertebral herniated nucleus pulposus. While the differentiation of non-neoplastic conditions, such as a Schmorl's node, from osseous metastatic spine disease can be elusive, it is essential for the appropriate management of patients with a history of malignancy.