Giant Schmorl's node: Another cause of increased FDG activity and intense uptake on bone scan

Learning Objectives 1. Review pathophysiology of Schmorl’s nodes. 2. Discuss the importance of correlating FDG PET and bone scan findings with radiological imaging of CT and MRI. 3. Illustrate FDG PET and bone scan findings of a giant Schmorl’s node.

Summary: While Schmorl’s nodes are common and are related to herniation of disc material into the vertebral endplate, giant Schmorl’s nodes are rare. The etiology and typical radiological presentation of Schmorl's node will be reviewed. We presented FDG PET and bone scan findings of a 78 year old female with a history of follicular cell thyroid carcinoma status post total thyroidectomy and radioiodine ablation therapy. The patient developed recurrence 6 years after initial diagnosis and was treated with surgical resection of L4 spinous process and a second I-131 NaI ablation. Subsequently, although multiple diagnostic I-131 scans were negative the patient continued to have elevated thyroglobulin prior to a FDG PET/CT study. The whole body FDG PET/CT scan was unremarkable except for focal increased FDG uptake in the right vertebral body of L2. A bone scan showed intense uptake at L2 which was reported as a bony metastasis. However, review of serial CT scans over 2 years and a MRI performed two years ago reveals features characteristic of a giant Schmorl’s node. The initial CT scan from 2006 showed a large lytic concavity at the right vertebral body of L2. The subsequent CT scans from 2007 and 2008 showed development of a sclerotic rim of the lesion, typical of a Schmorl’s node. MRI showed herniation of disc material through the superior endplate of L2 into the vertebral body.