Extradural developmental dural root sleeve cyst presenting as a lumbar paraspinal mass with renal compression in an infant.

Spinal extradural cysts do not normally present as a visible paraspinal mass or cause compression of the abdominal organs. The authors describe the case of a 9-month-old boy with multiple spinal extradural cysts. The largest of these cysts was along the right L-2 nerve root with significant extraspinal extension resulting in a visible slow-growing swelling in the right paraspinal region and radiological evidence of compression of the right kidney with hydronephrosis. Another large cyst along the left T-12 root caused radiologically evident compression of the left kidney but to a lesser degree. The patient also had monoparesis of the left lower limb and phenotypic features of Noonan syndrome. The authors performed marsupialization of the cysts, as well as repair of the fistula between the subarachnoid space and the cyst on the right side along the L-2 root and on the left side along the T-12 root. At 1-year follow-up, there was no paraspinal mass and the lower limbs exhibited normal power. Magnetic resonance imaging confirmed marked reduction in the size of the cysts and relief of the renal compression. To the authors' knowledge, their patient is the youngest reported in literature to have a spinal extradural cyst and also the first with the cyst presenting as a paraspinal mass.