Subpial lipoma of the spinal cord

We report the case of a 19-year-old woman with an ascending spastic paraparesis and sensory disturbance of both legs which have progressed in recent months with numbness and weakness of the upper limbs. There were no bowel or bladder complaints.

MRI examination revealed a well-circumscribed intradural mass on the posterior aspect of the spinal cord extending between C5 and T5. The lesion was hyperintense on both T1 and T2-weighted images and showed suppression on fat saturation sequence (Fig. 1 and 2). The cord was severely compressed, distorted and displaced anteriorly. No clear cleavage plane was seen between the mass and the cord (Fig. 3).

Spinal cord lipomas not associated with dysraphism are rare and account for only 1% of all spinal cord tumors [1]. Most of them are intradural and subpial thus they are located beneath the pia mater [1]. These usually affect the posterior surface of the medulla, hence dorsal column deficits are first to appear, leading to gait disturbances and loss of sensibility. They have a peak incidence in the 2nd or 3rd decade of life and the thoracic spine is the most common location followed by the cervicothoracic junction [2].

Subpial lipomas are inclusion tumours that arise from a disorder in embryogenesis [3, 4]. Histologically the fat content is composed of mature fat cells with no atypia, which lie in a compactly fibrous connective tissue stroma. They are not true neoplasms but they can increase in size because they behave metabolically identical to normal body fat pool and thus they may enlarge during periods of fat deposition [1-3].

Magnetic resonance imaging allows an accurate anatomical delineation of the tumour and its relationship to surrounding structures. These lesions show high signal on T1-weighted and T2-weighted images and no enhancement after administration of gadolinium. The high T1 and T2-weighted signal intensity decreases on the fat saturation sequences. Exophytic extension of the lipoma is seen in 45% of cases and when present, tends to be at the rostral end of the lesion [3]. Segmental anomalies of vertebra, like hemivertebra, or widening of spinal canal or neural foramina may also be associated [3, 5].

Total removal is usually not feasible because the margins are undefined and tightly attached to the neural parenchyma. Therefore, treatment usually consists in partial resection rather than gross total excision. Long-lasting resolution of any existing neurological deficits occurs in less than 50% of patients [2]. As in our case, in most patients, conservative decompression provides clinical stabilisation [3].

Written informed patient consent for publication has been obtained.