Localized hypertrophic mononeuropathy involving spinal roots and associated with sacral meningocele. Case report

Trigeminal hypertrophic interstitial neuropathy presenting as unilateral proptosis, ptosis, tearing, and facial neuralgia

Purpose

To show the utility of MRI and histology in diagnosing rare cases of trigeminal hypertrophic interstitial neuropathy (HIN).

Observations

A 57-year-old African-American woman presented with a 4-year history of right eye proptosis with tearing, headaches, and worsening right-sided trigeminal neuralgia symptoms and jaw pain. HIV and diabetes tests were negative and thyroid function was normal. MRI identified abnormal thickening of all trigeminal nerve divisions and proptosis secondary to right trigeminal nerve V1 division enlargement. The excised tissue contained S-100 positive Schwann cells in an onion-bulb pattern. Headaches resolved, but proptosis and mild trigeminal neuralgia remained 1 year post-surgery.

Conclusions and importance

Trigeminal HIN is very rare, but presents as chronic progressive ocular symptoms with trigeminal neuralgia. Trigeminal nerve hypertrophy is identified by MRI and confirmed histopathologically by detection of Schwann cells in an onion bulb formation.

Localized hypertrophic neuropathy of the sciatic nerve in children: MRI findings

BACKGROUND

Localized hypertrophic neuropathy (LHN) of the sciatic nerve in children is a rare condition characterized by a painless neurological deficit in the sciatic nerve territory.

OBJECTIVE

To demonstrate the role of MRI using a specific protocol and describe the primary findings in LHN.

MATERIALS AND METHODS

Imaging in four children (age 2 years to 12 years) is presented. All children presented with lower limb asymmetry. Three had a steppage gait. LHN was confirmed by electrophysiological studies and by MRI of the whole sciatic nerve with a dedicated protocol covering the lumbar spine and the lower limb.

RESULTS

There were four direct MRI findings: (1) linear and focal hypertrophy with progressive enlargement of a peripheral nerve or plexus diameter, (2) abnormal hyperintensity of the nerve on T2-weighted images, (3) preserved fascicular configuration, and (4) variable enhancement after intravenous gadolinium administration. In addition there were atrophy and fatty infiltration of innervated muscles. MRI was helpful for determining the extent of lesions and in excluding peripheral nerve compression or tumour.

CONCLUSION

MRI of the whole sciatic nerve is the method of choice for diagnosing LHN of the sciatic nerve.

Solitary localised hypertrophic neuropathy of the cauda equina

Localised hypertrophic neuropathy (LHN) is an uncommon non-neoplastic lesion, which is rare in the central nervous system. We report a patient with LHN of the cauda equina. Pre-operatively these lesions cannot be differentiated from schwannoma or other benign tumours or expansions of the nerve roots. Treatment is generally surgical, largely to confirm the diagnosis, and examination of the surgical specimen reveals an expansion of the nerve by "onion bulb" whorls of Schwann cells (S-100 positive). Multiple lesions may be associated with the generalised diffuse hypertrophic neuropathies or chronic inflammatory demyelinating polyneuropathies. It should be differentiated from intraneural perineuroma, which has a similar appearance but comprises perineural cells (epithelial membrane antigen positive). Adjuvant therapy is not required.

Pseudoneoplasms of the Nervous System

Context.—Pseudoneoplasms of the nervous system vary greatly in nature. Ranging from inflammatory to autoimmune, infectious, malformative, reactive, degenerative, and radiation induced, they all mimic true tumors. Thus, they have the potential to mislead clinicians, radiologists, and pathologists alike. Their clinical and/or neuroimaging and histologic features are readily misinterpreted as tumor. Knowledge of the pitfalls is essential to avoid mismanagement, specifically overtreatment. In such instances, pathologists must take the entire clinical picture into consideration, acquainting themselves with presenting symptoms, physical findings, and neuroimaging.

Objective.—To present 10 examples of pseudoneoplasms of the nervous system, analyze the basis for their mimicry, and discuss their differential diagnosis.

Data Sources.—Review of the pertinent literature related to pseudoneoplasms of the nervous system and review of the consultation files of one of the authors (B.W.S.).

Conclusions.—The identification of tumor mimics may be difficult under the best of circumstances, and maintaining a broad differential diagnosis as well as application of a variety of immunocytochemical and occasionally ultrastructural and/or molecular genetic methods is essential to arrive at a correct diagnosis.

Intraneural perineurioma: a systematic review with illustrative cases

CONTEXT

Intraneural perineurioma may be confused with other "onion bulb" Schwann cell entities (localized hypertrophic neuropathy, reactive/demyelinating processes, or inherited polyneuropathies of Charcot-Marie-Tooth/Dejerine Sottas) due to similar clinical, radiologic, and histologic features. Perineurial and Schwann cells can only be differentiated by ultrastructure and immunohistochemsitry.

OBJECTIVE

To identify and summarize the clinicopathologic features of true cases of intraneural perineurioma from the English language literature.

DATA SOURCES

A systematic review was performed on definitive intraneural perineuriomas identified through Medline. Baylor College of Medicine-affiliated hospitals' anatomic pathology databases yielded 2 illustrative intraneural perineurioma cases.

STUDY SELECTION

Intraneural perineurioma inclusion criteria consisted of characteristic histology and confirmation of perineurial cell lineage by either immunohistochemistry (epithelial membrane antigen positive, S100 protein negative) and/or ultrastructural analysis (thin cytoplasmic processes with an incomplete basal lamina, poorly formed tight junctions, and pinocytotic vesicles).

DATA EXTRACTION

Clinicopathologic data were extracted from all identified articles, with subsequent statistical analysis of the following parameters: age, sex, race, tumor location, tumor size, duration of symptoms prior to diagnosis, treatment modalities and outcomes measures, follow-up assessment for tumor recurrence and metastasis, clinical features (history of trauma, motor/sensory abnormalities, clinical/family history), and diagnostic workup (routine histology, immunohistochemistry, ultrastructural analysis, and molecular/cytogenetic characteristics).

CONCLUSIONS

Intraneural perineurioma is a neoplastic proliferation of perineurial cells with unique immunohistochemistry and ultrastructural features, and it is distinct from other onion bulb Schwann cell-derived entities. Despite harboring molecular abnormalities of the long arm of chromosome 22, intraneural perineurioma has not been associated with neurofibromatosis. Intraneural perineurioma is a benign peripheral nerve sheath tumor that does not recur or metastasize.

Hypertrophic mononeuropathy

Hypertrophic localized mononeuropathy is a condition that comes to clinical attention as a painless focal swelling of a peripheral nerve in an arm or leg and is associated with a slow but progressive loss of motor and sensory function. Whether the proliferation of perineurial cells is neoplastic or degenerative--an ongoing controversy among nerve pathologists--for some patients resection of the involved portion of a nerve with autologous interposition grafting results in better functional outcome than allowing disease to follow its natural course. Patients with a painless focal enlargement of a nerve associated with progressive weakness and/or sensory loss may benefit from surgery for resection and grafting.

Nonneoplastic peripheral nerve tumors

Most of the nonneoplastic tumor-like lesions affecting the peripheral nervous system are rarely encountered. In many situations, a good history of the presenting symptoms can suggest a reactive or infectious neuroma. The physical examination can also suggest an inflammatory or hyperplastic lesion. In some cases, however, the correct diagnosis can only be made at surgery. Nonetheless, awareness of these lesions is important in limiting unnecessarily aggressive surgical procedures. Patients suspected of having nonneoplastic lesions are followed and treated surgically for symptomatic relief or when the diagnosis is unclear. In some situations, the surgical treatment of choice may be debated. Nevertheless, we adopt a conservative approach to these lesions and reserve more aggressive techniques for cases that do not respond to more conservative means.

Hypertrophic Neuropathy of the Cauda Equina: Case Report

OBJECTIVE AND IMPORTANCE

Hypertrophic neuropathy of the cauda equina (HNCE) is a rare form of peripheral neuropathy. The diagnosis is complicated by an insidious clinical presentation and complex radiographic images. We present a case of HNCE caused by chronic inflammatory demyelinating polyneuropathy with symptomatic improvement after decompressive lumbar laminectomy and dural expansion.

CLINICAL PRESENTATION

A 54-year-old woman with a history of back pain since she was in her 20s presented with low back and radicular pain that had increased during a period of 6 months, bilateral lower-extremity weakness, and sensory loss in the right thigh. Magnetic resonance imaging of the lumbosacral spine revealed multiple, poorly enhancing mass lesions and apparent intrathecal nerve root thickening from L1 to L5.

INTERVENTION

An L1-L5 decompressive laminectomy, performed with continuous somatosensory evoked potential and electromyographic monitoring, revealed multiple segmentally enlarged nerve roots. One nerve root that did not respond to high levels of stimulation was identified. This root was resected and submitted for pathological analysis. The dura was expanded with an 11-cm-long dural patch. The pathological examination revealed hypertrophic neuropathy, with extensive S-100-positive “onion bulb” formation. The patient's symptoms improved postoperatively.

CONCLUSION

HNCE is a rare disorder that can cause radicular pain and lower-extremity weakness, sensory loss, and hyporeflexia. One possible cause is demyelinating polyneuropathy. Although medical management is typically effective in the treatment of demyelinating polyneuropathy, it has little effect on compressive symptoms caused by intradural nerve root enlargement. As this case demonstrates, surgical management of symptomatic radiculopathy by lumbar laminectomy is a reasonable and effective approach to the treatment of HNCE.

Radial nerve palsy owing to localized hypertrophic neuropathy (intraneural perineurioma) in early childhood

Localized hypertrophic neuropathy, also termed intraneural perineurioma, is a rare disorder of unknown etiology that produces a slowly progressive painless focal lesion of a peripheral nerve. It is characterized histologically by concentric whorls ("onion bulbs") of epithelial membrane antigen-reactive, S-100 protein-negative perineurial cells surrounding nerve fibers. We report a radial nerve palsy in a child aged 2 years in whom the diagnosis of localized hypertrophic neuropathy was made by biopsy. Resection of the affected nerve segment and sural nerve grafting produced no useful recovery after 3 years, probably because of the long duration of denervation. When this mononeuropathy presents in early childhood, uncertainty over the time of onset can lead to difficulty in distinguishing this potentially treatable lesion from congenital and other causes of nerve palsy.

Localized hypertrophic neuropathy: magnetic resonance imaging findings and long-term follow-up

Four patients with painless, progressive focal neurological deficits that localized to peripheral nerve or plexus were eventually found to have the relatively rare condition of localized hypertrophic neuropathy or intraneural perineurioma. Magnetic resonance imaging (MRI) was an excellent tool for aiding in the precise localization of the lesion, if specifically tailored with regard to imaging planes and specific MRI sequences. Fat-saturated T2-weighted and fat-saturated T1-weighted postgadolinium images provided the best visualization, particularly with a high-field magnet and phase array body coil. Two patients stabilized following resection of the lesion and sural nerve grafting, and 1 had partial improvement in a proximal muscle following neurolysis.

Resection and graft repair for localized hypertrophic neuropathy

OBJECTIVES

Formulation of surgical management recommendations for localized hypertrophic mononeuropathy has been difficult because of the infrequency of the lesion, lack of precise pathological diagnosis, and uncertainties regarding its cause. The purpose of this retrospective review of the Louisiana State University (LSU) experience with this unusual neuropathy was to evaluate the efficacy of lesion resection and interposition grafting in its management.

METHODS

The charts of 15 patients operated on at LSU during a 15-year period with a pathological diagnosis of localized hypertrophic neuropathy were reviewed.

RESULTS

Hypertrophic lesions were located on major named peripheral nerves of the extremities, distributed equally to the upper and lower extremities. Family history was negative for all patients, and entrapment or trauma, other than previous surgery, were unlikely by symptom location or history. Weakness was the most common presentation. The mean length of symptoms was 76 months. Atrophy, sensory loss, Tinel's sign, focal tenderness, and a mass were found in the majority of patients. Preoperative electrophysiological studies showed chronic denervational changes in all patients. At surgery, if no action potential or one of low amplitude was recorded across the lesion, the lesion was resected and an autologous nerve graft measuring from 3.5 to 8.5 cm in length was interposed. During follow-up periods of 1 or more years, seven of nine patients with localized hypertrophic mononeuropathy treated with graft repairs were either unchanged or improved.

CONCLUSION

Localized hypertrophic mononeuropathy is a progressive process associated with pathological nerve changes that correlate with eventual severe functional loss. If intraoperative histological examination shows onion bulb neuropathy and intraoperative nerve action potentials confirm a nonfunctioning or poorly functioning segment, lesion resection with interposition graft repair provides the possibility of some degree of recovery.

Intratemporal facial nerve perineurioma

Forty-two cases of perineurioma have been reported in the literature. This report adds the first intratemporal facial nerve perineurioma to the literature and reviews the others. Unlike schwannoma and neurofibroma, the histological features of perineurioma demonstrate onion bulb-like structures with a strong positive immunoreactivity for epithelial membrane antigen. The clinical history of gradual facial nerve paresis was 15 years in the case presentation and the clinical diagnosis of tumor was overlooked.