The objective of this study was to assess peripheral nerve involvement and DNA mutation of the neurofibromatosis type 2 (NF2) gene (NF2) in a Taiwanese family with classic NF2. Eleven members (six symptomatic and five asymptomatic) of a family carrying NF2 underwent clinical examination, neuroimaging, and electrophysiological analysis. Mutation and linkage analyses were conducted on DNA samples prepared from peripheral blood (all individuals), a sural nerve biopsy specimen (one symptomatic member), and a tumor specimen (another symptomatic member). Six of the 11 members were diagnosed with classic NF2. DNA sequencing of the tumor specimen demonstrated a frameshift mutation with 756delC on exon 8 of NF2. Three affected subjects showed clinical variability of the neuropathic disorders. Electrophysiological studies demonstrated variation in the disease pattern and severity of peripheral nerve involvement in five affected subjects. The morphometric assessment of the sural nerve biopsy specimen showed a marked reduction in both large myelinated and unmyelinated fibre density and increased density of non-myelinating Schwann cell nuclei. Apart from numerous pathological nuclei of isolated Schwann cells, multiple profiles of non-myelinating Schwann cell subunits were apparent in the endoneurium. Schwann cell proliferation in association with first-hit mutation of the merlin gene might be responsible for the NF2-associated neuropathy. Sural nerve biopsy showed a progressive neuropathy in the disease. Further, we suggest nonmyelinating Schwann cells are involved in NF2 neuropathy.
We report the case of a 68-year-old man with a 6-year history of renal cell carcinoma (RCC), who presented with severe low backache and paraparesis for a month before admission. In addition, he experienced urinary retention for 2 weeks. A spinal magnetic resonance imaging scan revealed the presence of an intradural extramedullary solitary mass at the conus medullaris. We performed a laminectomy and completely excised the tumor. The histopathological findings were suggestive of spinal metastasis of RCC. After the operation, the patient did not complain of backache and urinary retention, and paraparesis improved significantly. Spinal metastases of RCC are usually extradurally located. Intradural metastases of RCC are rare. Thus far, only six cases of RCC metastasizing to the cauda equina have been reported; however, RCC metastasis to the conus medullaris has not yet been reported. Conus medullaris lesions may cause symmetrical motor and sensory deficits accompanied by early autonomic system impairment. Surgery is the treatment of choice in cases of resectable RCC metastases, especially in cases of solitary metastasis.
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