Giant fatty Schmorl's nodes: CT findings in four patients.

OBJECTIVE: To describe the CT features of an unusual type of lumbar Schmorl's node (SN) appearing as giant fatty lesion of the vertebral bodies. DESIGN AND PATIENTS: >Four patients (4 men; mean age 48.5 years) collected during a 9-month period were examined with MDCT for unremarkable lumbar symptoms; none had relevant history of specific trauma during the last years preceding the CT. RESULTS AND
CONCLUSIONS: The CT findings had a similar showing: a central or para-central osteolytic lesion in contact with the upper end plate of the vertebra, occupying about two-thirds to three-quarters of the body height and being surrounded by a thin and well-delineated bony rim. There was a clear interruption of the superior vertebral end plate above the lesion and an almost normal height of the adjacent vertebral disk. The CT appearance suggested a uniform fat content which was confirmed by density measurements ranging from -20 to -30 HU. The origin remains unknown, but a parallel is drawn between giant fatty SNs and giant cystic SNs. Intravertebral disk herniation is likely to be the initial phenomenon, with a preponderant responsibility of the "secondary induced intramedullar tissular disorders" to constitute the final size of the lesion. One hypothesis could be a fracture of trabecular bone with secondary hemorrhage and cystic or fatty degeneration. Alternatively, intramedullary vascular disturbances may lead to foci of bone necrosis that heal by fibroblastic proliferation followed by mucoid or fatty degeneration. It is also possible that giant fatty SNs could represent end stage of giant cystic SNs.