Inflammatory pseudotumor of nerve: clinicopathological characteristics and a potential therapy

Inflammatory Pseudotumor of the Ulnar Nerve Mimicking a Malignant Peripheral Nerve Sheath Tumor: A Radiologic Puzzle

Inflammatory pseudotumor (IPT) of a peripheral nerve is a rare non-neoplastic tumefactive inflammatory condition, often mimicking malignancy. The etiology of this condition is still unknown. Clinically and radiologically, the lesion can mimic a malignant tumor. This case report represents, as far as we know, the first publication describing the ultrasonography findings and the results of advanced dynamic contrast-enhanced magnetic resonance imaging (MRI) and diffusion-weighted MRI of IPT in a peripheral nerve. Suspicion of this entity on imaging can speed up the definitive diagnosis and potentially avoid overly radical treatment.

Neurosurgical Intervention for Nerve and Muscle Biopsies

(1) Background: Neurologic and musculoskeletal diseases represent a considerable portion of the underlying etiologies responsible for the widely prevalent symptoms of pain, weakness, numbness, and paresthesia. Because of the subjective and often nonspecific nature of these symptoms, different diagnostic modalities have been explored and utilized. (2) Methods: Literature review. (3) Results: Nerve and muscle biopsy remains the gold standard for diagnosing many of the responsible neurological and musculoskeletal conditions. However, the need for invasive tissue sampling is diminishing as more investigations explore alternative diagnostic modalities. Because of this, it is important to explore the current role of neurosurgical intervention for nerve and muscle biopsies and its current relevance in the diagnostic landscape of neurological and musculoskeletal disorders. With consideration of the role of nerve and muscle biopsy, it is also important to explore innovations and emerging techniques for conducting these procedures. This review explores the indications and emerging techniques for neurological intervention for nerve and muscle biopsies. (4) Conclusions: The role of neurosurgical intervention for nerve and muscle biopsy remains relevant in diagnosing many neurological and musculoskeletal disorders. Biopsy is especially relevant as a supportive point of evidence for diagnosis in atypical cases. Additionally, emerging techniques have been explored to guide diagnostics and biopsy, conduct less invasive biopsies, and reduce risks of worsening neurologic function and other symptoms secondary to biopsy.

Treatment approach to isolated common peroneal nerve palsy by mechanism of injury: Systematic review and meta-analysis of individual participants' data

BACKGROUND

We reviewed the individual participant data of patients who sustained isolated common peroneal nerve (CPN) injuries resulting in foot drop. Functional results were compared between eight interventions for CPN palsies to determine step-wise treatment approaches for the underlying mechanisms of nerve injury.

METHODS

PubMed, Embase, Cochrane Library, Web of Science, Scopus, and CINAHL databases were searched. PRISMA-IPD and Cochrane guidelines were followed in the data search. Eligible patients sustained isolated CPN injuries resulting in their foot drop. Patients were stratified by mechanisms of nerve injury, ages, duration of motor symptoms, and nerve defect/zone of injury sizes, and were compared by functional results (poor = 0, fair = 1, good = 2, excellent = 3), using meta-regression between interventions. Interventions evaluated were primary neurorrhaphy, neurolysis, nerve grafts, partial nerve transfer, neuromusculotendinous transfer, tendon transfer, ankle-foot orthosis (AFO), and arthrodesis.

RESULTS

One hundred and forty-four studies included 1284 patients published from 1985 through 2020. Transection/Cut: Excellent functional results following tendon transfer (OR: 126, 95%CI: 6.9, 2279.7, p=0.001), compared to AFO. Rupture/Avulsion: Excellent functional results following tendon transfer (OR: 73985359, 95%CI: 73985359, 73985359, p<0.001), nerve graft (OR: 4465917, 95%CI: 1288542, 15478276, p<0.001), and neuromusculotendinous transfer (OR: 42277348, 95%CI: 3001397, 595514030, p<0.001), compared to AFO. Traction/Stretch: Good functional results following tendon transfer (OR: 4.1, 95%CI: 1.17, 14.38, p=0.028), compared to AFO. Entrapment: Excellent functional results following neurolysis (OR: 4.6, 95%CI: 1.3, 16.6, p=0.019), compared to AFO.

CONCLUSIONS

Functional results may be optimized for treatments by the mechanism of nerve injury. Transection/Cut and Traction/Stretch had the best functional results following tendon transfer. Rupture/Avulsion had the best functional results following tendon transfer, nerve graft, or neuromusculotendinous transfer. Entrapment had the best functional results following neurolysis.

Nerve biopsy: Current indications and decision tools

After initial investigation of patients presenting with symptoms suggestive of neuropathy, a clinical decision is made for a minority of patients to undergo further assessment with nerve biopsy. Many nerve biopsies do not demonstrate a definitive pathological diagnosis and there is considerable cost and morbidity associated with the procedure. This highlights the need for appropriate selection of patients, nerves and neuropathology techniques. Additionally, concomitant muscle and skin biopsies may improve the diagnostic yield in some cases. Several advances have been made in diagnostics in recent years, particularly in genomics. The indications for nerve biopsy have consequently changed over time. This review explores the current indications for nerve biopsies and some of the issues surrounding its use. Also included are comments on alternative diagnostic modalities that may help to supplant or reduce the use of nerve biopsy as a diagnostic test. These primarily include extraneural biopsy and neuroimaging techniques such as magnetic resonance neurography and nerve ultrasound. Finally, we propose an algorithm to assist in deciding when to perform nerve biopsies.

Cervical Sympathetic Trunk-Centered Inflammatory Myofibroblastic Tumor Complicated with Postoperative First Bite Syndrome

Inflammatory myofibroblastic tumors (IMTs) in the head and neck region are common, but those with sympathetic trunk involvement are extremely rare. Here we present a case of cervical sympathetic trunk-centered IMT which is also accompanied by ipsilateral carotid artery, internal jugular vein, and vagus nerve involvement. The patient initially complained of an episodic painful swelling on the right side of the neck and underwent surgery. Preoperative and postoperative serum IgG4 level during 3-year follow-up time is within normal limits. Immunohistochemical study of the tumor has also revealed negativity to IgG4. Postoperative first bite syndrome (FBS) was observed. Surgery seems to be first-line therapy in the patient with IgG4-negative IMT.

Inflammatory Pseudotumor of the Infraorbital Nerve: A Rare Diagnosis to Be Aware of

Inflammatory pseudotumor (IPT) is a rare benign mass-forming disease that can arise anywhere throughout the body, mimicking a wide spectrum of other conditions. Its diagnosis can be challenging, especially when it involves uncommon sites. The authors report a patient of an atypical localization of IPT, occurred as an enlarging bulk in the infraorbital nerve channel in a patient who presented with facial numbness. Clinical and radiological aspects similar to schwannoma led to misdiagnosis and over-treatment. The differential diagnosis of an infraorbital mass should include IPT and the least invasive treatment should be preferred, as steroid therapy being the first-line treatment for IPT.

Neuromuscular complications in cancer

Cancer is becoming a treatable and even often curable disease. The neuromuscular system can be affected by direct tumor invasion or metastasis, neuroendocrine, metabolic, dysimmune/inflammatory, infections and toxic as well as paraneoplastic conditions. Due to the nature of cancer treatment, which frequently is based on a DNA damaging mechanism, treatment related toxic side effects are frequent and the correct identification of the causative mechanism is necessary to initiate the proper treatment. The peripheral nervous system is conventionally divided into nerve roots, the proximal nerves and plexus, the peripheral nerves (mono- and polyneuropathies), the site of neuromuscular transmission and muscle. This review is based on the anatomic distribution of the peripheral nervous system, divided into cranial nerves (CN), motor neuron (MND), nerve roots, plexus, peripheral nerve, the neuromuscular junction and muscle. The various etiologies of neuromuscular complications - neoplastic, surgical and mechanic, toxic, metabolic, endocrine, and paraneoplastic/immune - are discussed separately for each part of the peripheral nervous system.

Infantile inflammatory pseudotumor of the facial nerve as a complication of epidermal nevus syndrome with cholesteatoma

The first reported case of facial paralysis due to an inflammatory pseudotumor (IPT) of the facial nerve as a complication of epidermal nevus syndrome (ENS) is herein presented. A 10-month-old female patient was diagnosed with ENS at 3 months of age. She was referred to us because of moderate left facial paralysis. Epidermal nevi of her left auricle extended deep into the external ear canal. Otoscopy revealed polypous nevi and cholesteatoma debris filling the left ear. Computed tomography showed a soft mass filling the ear canal, including the middle ear, and an enormously enlarged facial nerve. Surgical exploration revealed numerous polypous nevi, external ear cholesteatoma, and tumorous swelling of the facial nerve. The middle ear ossicles were completely lost. The facial paralysis was improved after decompression surgery, but recurred 5 months later. A second operation was conducted 10 months after the first. During this operation, facial nerve decompression was completed from the geniculate ganglion to near the stylomastoid foramen. Histological diagnosis of the facial nerve tumor was IPT probably caused by chronic external ear inflammation induced by epidermal nevi. The facial paralysis gradually improved to House-Blackmann grade III 5 years after the second operation.

Malignant cell infiltration in the peripheral nervous system

The peripheral nervous system can be affected by malignancies involving different mechanisms. Neoplastic nerve lesion by compression, invasion, and infiltration is rare and occurs in particular in leukemia (neuroleukemiosis) and lymphoma (neurolymphomatosis). Its occurrence is much rarer in cancer, and even less so in sarcoma. The neoplastic infiltration of peripheral nerves by solid tumors is characterized by specific topographical sites such as the base of the skull, the ear, nose and throat region, and the cervico-brachial plexus as well as the lumbar and sacral plexus. Rarely malignant invasion affects the cranial nerves of the face where it can spread centripetally. Autonomic nerves and ganglia can also be affected. The retrograde spread of cancer in nerves is a bad prognostic sign. The clinical diagnosis is determined by tumor type, the pattern of involvement, and often pain.

Pathology of peripheral nerve sheath tumors: diagnostic overview and update on selected diagnostic problems

Peripheral nerve sheath tumors are common neoplasms, with classic identifiable features, but on occasion, they are diagnostically challenging. Although well-defined subtypes of peripheral nerve sheath tumors were described early in the history of surgical pathology, controversies regarding the classification and grading of these tumors persist. Advances in molecular biology have provided new insights into the nature of the various peripheral nerve sheath tumors, and have begun to suggest novel targeted therapeutic approaches. In this review, we discuss current concepts and problematic areas in the pathology of peripheral nerve sheath tumors. Diagnostic criteria and differential diagnosis for the major categories of nerve sheath tumors are proposed, including neurofibroma, schwannoma, and perineurioma. Diagnostically challenging variants, including plexiform, cellular and melanotic schwannomas are highlighted. A subset of these affects the childhood population, and has historically been interpreted as malignant, although current evidence and outcome data suggest they represent benign entities. The growing current literature and the author's experience with difficult to classify borderline or "hybrid tumors" are discussed and illustrated. Some of these classification gray zones occur with frequency in the gastrointestinal tract, an anatomical compartment that must always be entertained when examining these neoplasms. Other growing recent areas of interest include the heterogeneous group of pseudoneoplastic lesions involving peripheral nerve composed of mature adipose tissue and/or skeletal muscle, such as the enigmatic neuromuscular choristoma. Malignant peripheral nerve sheath tumors (MPNST) represent a diagnostically controversial group; difficulties in grading and guidelines to separate "atypical neurofibroma" from MPNST are provided. There is an increasing literature of MPNST mimics which neuropathologists must be aware of, including synovial sarcoma and ossifying fibromyxoid tumor. Finally, we discuss entities that are lacking from the section on cranial and paraspinal nerves in the current WHO classification, and that may warrant inclusion in future classifications. In summary, although the diagnosis and classification of most conventional peripheral nerve sheath tumors are relatively straightforward for the experienced observer, yet borderline and difficult-to-classify neoplasms continue to be problematic. In the current review, we attempt to provide some useful guidelines for the surgical neuropathologist to help navigate these persistent, challenging problems.