Background. Primary true isolated metastasis in a peripheral nerve tru
nk is considered a rare phenomenon Several routes of tumor invasion of
the peripheral nervous system from different types of cancer and in v
arious anatomic locations have been described in the literature; howev
er, the brachial plexus is an uncommon site of such blood-born metasta
ses. Methods. Five patients with severe brachial plexus neuropathy wit
hout obvious external signs of tumor masses and no detectable regional
lymph node involvement underwent exploration of the plexus. Results.
Isolated metastatic deposits were identified inside the nerve trunks.
Radiation therapy to the area of the lesion provided. good symptomatic
relief to all patients and local arrest of the disease to four of fiv
e. Conclusions, Despite its rich vascularity, the Peripheral nerve has
relative resistance to metastatic spread because there are blood-nerv
e barriers. This barrier should be investigated further in a tumor mod
el.