Extradural haemangiolipoma in the spinal canal. Two cases presenting during pregnancy.

Extradural spinal haemangiolipomas are very rare but they account for forty per cent of all lipomas in this position. The two cases described here were middleaged women who both had a paraparesis during their pregnancy which remitted after parturition. Both tumours were in the thoracic region on the posterior surface of the dura. The histological appearances were those of a lipoma with a definite capillary component. The pathogenesis of the relapsing and remitting paraplegia and its relationship with pregnancy is probably multi-factorial. It is proposed that both blood volume and extra-cellular fluid volume changes occurring during pregnancy may be responsible for the fluctuating cord compression. Similarly the hypothesis is put forward that due to the vascularity of the tumour it exerts a "steal" phenomenon over the blood supply to the adjacent cord. Also, because of its vascularity, the tumour could have a pulsatile compressive effect on the cord.