Melanotic cyst of L5 spinal root: A case report and review of literature
A 45-year-old hypertensive woman presented with history of low back pain for past one week which was abrupt in onset and severe in nature. The pain was non-radiating and confined to low back on the left side, affecting her activities of daily life. On examination, she had paraspinal spasm without any neurological deficits. There were no neurocutaneous markers. Magnetic resonance imaging (MRI) of lumbosacral spine revealed a well defined extra-spinal oval lesion measuring 2.1×1.5×1.8 cm in the left L5-S1 neural foramen causing widening of the canal with a large globular paraspinal mass. The lesion was hypointense on T1 and T2 weighted images with heterogeneous contrast enhancement suggestive of spinal nerve sheath tumor []. Left hemilaminectomy and complete facetectomy was done to visualize a jet-black cystic tumor with thin capsule arising from L5 root in the right neural foramen with para-spinal extension []. As the tumor was being dissected the cyst opened up, which revealed a black cyst fluid with shimmering particles in it. The cyst wall was dissected from the L5 nerve root and removed gross totally. Histopathology revealed small fragments of fibro-collagenous stroma and ganglion cells with no specific cell lining. Cyst contained brownish black pigment that was bleached with melanin bleach and was negative for Pearl's stain []. Post-operatively, patient was completely relieved of her low back pain. She has been on follow-up for more than one and half years with no recurrent symptoms and repeat MRI spine showed no recurrence of lesion.