A migrated lumbar disc herniation simulating a dumbbell tumor.

We report a case of a migrated lumbar disc hemiation, which on magnetic resonance imaging (MRI) simulated a dumbbell tumor in a 44-year-old woman who had severe pain in her right buttock and leg. A large epidural mass mimicking a dumbbell tumor was detected at the L5 vertebral level by MRI and computed tomography over myelography. Surgical fenestration of the L4/L5 interlaminar space revealed a dorsolateral epidural mass connected to the L5/S1 intervertebral disc extending laterally through the right L5/S1 intervertebral foramen. Histologically, it was degenerative disc material without active inflammation. Reevaluation of the MRI suggested some clues that might be useful in differentiating such a herniated disc from an epidural tumor.