To date more than 50 cases of intraneural perineuroma
have been documented by histological analysis and
in most immunoreactivity has also been demonstrated
with epithelial membrane antigen positivity and S-100
protein negativity[
7,
8,
13-
16]. The literature is divided
as to whether this lesion is truly neoplastic or represents
an inflammatory process caused by repeated trauma and
resultant loss of integrity of the normal perineural barrier.
Using tissue culture, cytogenetics and fluorescent in situ
hybridization, Emory and colleagues[
5] demonstrated
that the intraneural perineuroma represents a neoplasm
consistent with loss of gene on chromosome 22, similar to
findings in other peripheral nerve tumors and intracranial
meningiomas. Because of genetic evidence, those authors
argued that the most descriptive and accurate term for
this lesion is ‘intraneural perineurioma' however, in their
recent study, Gruen et al.[
7] referred to this lesion as a
localized hypertrophic neuropathy, despite their argument
that is rare to find history consistent with reactive change.
Authors of other recent reports have also referred to this
lesion as localized hypertrophic neuropathy and perineurioma
interchangeably[
13].
Grossly, the affected nerve shows a characteristic
fusiform enlargement with thickening and adhesions involving
the perineural elements. This finding is in contrast
to a schwannoma, which can be ‘shelled out' from
the involved nerve. Light microscopy of the lesion shows
onion-bulb formation of nerve fascicles. This finding is
thought to be caused by schwann cell hyperplasia[7]. Results
of immunohistochemistry studies of concentric are
positive for epithelial membrane antigen and negative for
S-100 protein. Results of central myelin sheath immunohistochemistry
studies are negative for epithelial membrane
antigen but positive for S-100 protein.
Because of the small number of case reports no consensus
has been made about proper management of these
lesions. There was no recurrence of lesions after excision.
However, in the case reports in which excision of lesions
performed, return of sensory nerve function was not seen,
even with interpositional nerve grafts[4,14,17]. Conservative
management has been advocated, with incisional
biopsy of lesion for diagnosis. Excision of the mass has
been recommended if the lesion can be easily dissected
from involved nerve[5]. Additionally MR neurography can be used to evaluate dicision of intraneural microscopic
resection with preservation of surrounding fascicles or
a segmental resection with placement of nerve graft[13].
In our patient, we performed incisional biopsy and carpal
tunnel release. Furthermore, because of the rarity of this
clinical entity, intraoperative diagnosis is not possible in
most centers. Therefore, we believe that each case needs
to be individualized until more information is available
regarding this tumor.
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