Lipomas

Robert Grant MD (Dr. Grant of the Edinburgh Centre for Neuro-Oncology has no relevant financial relationships to disclose.)
Edward J Dropcho MD, editor. (Dr. Dropcho of Indiana University Medical Center has no relevant financial relationships to disclose.)
Originally released December 10, 1997; last updated February 24, 2015; expires February 24, 2018

This article includes discussion of lipomas, intracranial lipomas, and intraspinal lipomas. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Intracranial and intraspinal lipomas are congenital or developmental in origin and are not true neoplasms. They occur throughout the neuroaxis, but are most commonly found in the midline or just lateral to midline structures. Most intracranial lipomas are identified incidentally and do not change over 5 or more years of interval scanning. Some are associated with midline facial and palatal abnormalities in conjunction with callosal agenesis. Focal disturbances in cerebral cortical development have been shown to occur in association with cerebral lipomas. Epilepsy is a common association and complication. Spinal lipomas generally affect the lumbosacral spine and should only be approached if symptoms are disabling, intractable, and worsening and the cord is displaced or tethered. Long-term prognosis for patients receiving total resection of spinal cord lipoma is much better than that of partial resection, which often produces worse scarring and poorer long-term outcome than conservative management. A cord to sac ratio greater than 50% (tight sac) predicts poorer surgical outcome. In this article, the author reviews the evidence for intervention.

Key points

 

• Lipomas are most commonly found in the midline and are frequently asymptomatic.

 

• Lipomas may be associated with additional dystrophic and congenital malformations.

 

• Most lipomas grow very slowly or not at all, and conservative management is advised in the absence of symptoms and signs.

 

• Surgery on intracranial lipomas does not usually improve seizure control.

 

• In symptomatic filum terminale lipomas, early surgery may improve symptoms for many years.

 

• Surgery for symptomatic lipomas involving brain, brainstem, cerebellopontine angle, and cervicothoracic cord are equally as likely to further deteriorate as to improve.

Historical note and terminology

Intracranial and intraspinal lipomas are congenital or developmental in origin and are not true neoplasms. The first description of an intracranial lipoma has been attributed to Meckel in 1818, who described a lipoma of the optic chiasm. Several years later, Rokitansky described the pathology of a lipoma of the corpus callosum. Mori classified lipomas involving the nervous system pathologically and embryologically into 4 groups (Mori 1985): (1) hyperplasia of fat normally seen in the pia, (2) lipomatous transformation of connective tissue, (3) displacement or inclusion of embryonic cells during formation of the central nervous system, and (4) aberrant growths related to the development of primitive layers of the meninges originating from the embryonic mesenchyme. A new classification system has been proposed for congenital spinal lipomas, dividing them into those without a dural defect (Group 1) and those with a dural defect (Group 2), which reflect differences in embryology, clinical presentation, operative findings, complications, and prognosis (Muthukumar 2009a). Within each group there are several subtypes: (Group 1: filum lipoma, caudal lipoma, and intramedullary lipoma; Group 2: dorsal lipoma, caudal lipoma, transitional lipoma, lipomyelocele, and lipomyelomeningocele).

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