Intradural extramedullary spinal nerve sheath myxoma: a report of two cases.

Nerve sheath myxoma, a myxoid variant of schwannoma, is a dermal tumor that usually occurs in the upper extremities, head and neck region, or trunk; occasionally, however, it has also been reported to develop in the spinal canal. Here, we describe two cases of intraspinal nerve sheath myxoma. Case 1 was a 74-year-old man with left hypochondrial pain. Gadolinium-enhanced magnetic resonance imaging (MRI) of his spine revealed a well-demarcated intradural extramedullary tumor with peripheral enhancement at the Th8 level. Case 2 was a 58-year-old man with lower back and left buttock pain. Gadolinium-enhanced MRI revealed a well-demarcated intradural extramedullary tumor with peripheral enhancement at the Th12-L1 level. Both cases were clinically diagnosed as schwannoma. Histological studies revealed characteristic myxoid lobules which were separated by fibrous septa or bands of more compact cellular area. The tumor cells were diffusely positive for S-100 and focally positive for Schwann/2E, which reacts with Schwann cells and myelin in the peripheral nervous system. The positive reaction to Schwann/2E confirmed the occurrence of peripheral nerve sheath differentiation. Nerve sheath myxoma should be included in differential diagnosis of spinal canal tumors.