Spinal Lipoma¶

Definition¶

Spinal lipomas are benign fatty tumors that can occur in several forms within or adjacent to the spinal canal. They range from incidental intradural lipomas to clinically significant lipomyelomeningoceles associated with spinal dysraphism. In the context of neoplasms, the most relevant types are intradural lipomas and lipomas of the filum terminale.

Types¶

Intradural Lipoma¶

True intramedullary neoplasm composed of mature fat
Most common in the cervical and thoracic cord
May expand the cord but rarely causes significant neurological compromise
Entirely intradural, not associated with a skin defect

Lipoma of the Filum Terminale¶

Filar lipoma — fatty infiltration of the filum terminale
Very common incidental finding (present in up to 4% of MRIs)
Most are clinically insignificant
If the filum is thickened (>2 mm) with an associated low-lying conus (below L2–L3), consider tethered cord syndrome

Lipomyelomeningocele¶

A form of occult spinal dysraphism where a lipoma is continuous with the spinal cord through a posterior bony defect
Primarily a congenital/developmental condition — discussed in the Congenital/Developmental category

Imaging Findings¶

MRI¶

T1-weighted — High signal (bright), following fat signal. This is the diagnostic hallmark — lipomas are among the brightest structures on T1.
T2-weighted — High signal (but less bright than T1)
Fat-saturated sequences — The lesion loses signal completely on fat-saturated images, confirming its fatty nature. This is the definitive test.
No enhancement — Mature lipomas do not enhance. Enhancement within a fatty lesion should raise concern for liposarcoma (exceedingly rare in the spine).
Location — Intradural, subpial, intimately associated with the cord substance

CT¶

Fat attenuation (-40 to -120 HU)
Well-defined
No calcification or enhancement

Clinical Pearl

A T1-bright intradural lesion that completely suppresses on fat saturation is a lipoma — no further workup needed. The main diagnostic pitfall is confusing a lipoma with a dermoid cyst, which can also be T1-bright. Dermoids are more heterogeneous and may show restricted diffusion if ruptured. A lipoma of the filum terminale is almost always incidental, but if accompanied by a low-lying conus (2 mm), evaluate for tethered cord.

Key Points¶

Spinal lipomas are T1-bright and suppress completely on fat saturation
Intradural lipomas are benign and often incidental
Filar lipomas are common incidental findings — clinically significant only if associated with tethered cord
No enhancement in mature lipomas
Lipomyelomeningoceles are congenital malformations discussed separately

References¶

Gaillard F, et al. Intradural spinal lipoma. Radiopaedia.org. Available from: https://radiopaedia.org/articles/intradural-spinal-lipoma
Gaillard F, et al. Lipomyelomeningocele. Radiopaedia.org. Available from: https://radiopaedia.org/articles/lipomyelomeningocele-1
Kolb L, Yarrarapu SNS, Robson O, Rosario-Collazo JA. Lipoma. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2026. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507906/
Cools MJ, Al-Holou WN, Stetler WR Jr, Wilson TJ, Muraszko KM, Ibrahim M, et al. Filum terminale lipomas: imaging prevalence, natural history, and conus position. J Neurosurg Pediatr. 2014;13(5):559-67.
Trapp B, Freddi TAL, Hans MOM, Calixto IFTL, Fujino E, Rojas LCA, et al. A practical approach to diagnosis of spinal dysraphism. RadioGraphics. 2021;41(2):559-75.
Patwardhan V, Patanakar T, Patkar D, Armao D, Mukherji SK. MR imaging findings of intramedullary lipomas. AJR Am J Roentgenol. 2000;174(6):1792-3.