When biopsy goes wrong: a case series of misdiagnoses and complications from biopsies of masses of unknown origin potentially originating from a peripheral nerve.

OBJECTIVE: Biopsies of peripheral nerve tumors (PNTs) are often used to plan an efficient treatment strategy. However, performing a biopsy is controversial when the mass is likely to be a benign PNT (BPNT). The aim of this study was to evaluate the side effects of biopsies in patients with potential PNTs. METHODS: A retrospective and cross-sectional study was conducted on 24 patients who underwent biopsy of a mass of unknown origin potentially originating from a peripheral nerve (MUOPON), performed in nonspecialty services, and who were later referred to the authors' service for resection of their lesion between January 2005 and December 2022. The patients were evaluated for pain score, presence of a motor or sensory deficit, biopsy diagnosis, and definitive histopathological postsurgical diagnosis. RESULTS: The location of the tumor was supraclavicular in 7 (29.2%) patients, in the axillary region in 3 (12.5%), in the upper limb in 7 (29.2%), and in the lower limb in 7 (29.2%). Twenty-one (87.5%) patients were evaluated by MRI before biopsy, and 3 (12.5%) underwent ultrasound. One patient did not have an examination before the procedure. Based on the biopsy findings, 12 (50%) analyses had an inconclusive histopathological result. The preexisting pain worsened, as measured 1 week after biopsy, in all patients and had remained unchanged at the first evaluation by the authors (median 3 months, range 2-4 months). In 1 case, the open biopsy had to be interrupted because the patient experienced excruciating pain. Four (16.7%) patients developed motor deficits. Subsequent surgery was hampered by scar formation and intratumoral hemorrhage in 5 (20.8%) patients. The initial diagnosis obtained by biopsy differed from the final histopathological diagnosis in all patients, of whom 21 (87.5%) had BPNTs, 2 (8.3%) malignant peripheral nerve sheath tumors, and 1 (4.2%) an ancient schwannoma. CONCLUSIONS: Biopsies of PNTs are controversial and may result in misdiagnosis, neuropathic pain, or neurological deficit due to axonal damage, and they may also hinder microsurgical resection when if performed when not indicated. Indications for biopsy of an MUOPON must be carefully considered, especially if BPNT is a possible diagnosis.

MRI features of benign peripheral nerve sheath tumors: how do sporadic and syndromic tumors differ?

OBJECTIVES: To compare MRI features of sporadic and neurofibromatosis syndrome-related localized schwannomas and neurofibromas. METHODS: In this retrospective study, our pathology database was searched for "neurofibroma" or "schwannoma" from 2014 to 2019. Exclusion criteria were lack of available MRI and intradural or plexiform tumors. Qualitative and quantitative anatomic (location, size, relationship to nerve, signal, muscle denervation) and functional (arterial enhancement, apparent diffusion-weighted coefficient) MRI features of sporadic and syndrome-related tumors were compared. Statistical significance was assumed for p < 0.05. RESULTS: A total of 80 patients with 64 schwannomas (sporadic: 42 (65.6%) v. syndrome-related: 22 (34.4%)) and 19 neurofibromas (sporadic: 7 (36.8%) v. syndrome-related: 12 (41.7%)) were included. Only signal heterogeneity (T2W p=0.001, post-contrast p=0.03) and a diffused-weighted imaging target sign (p=0.04) were more frequent with schwannomas than neurofibromas. Sporadic schwannomas were similar in size to syndrome-related schwannomas (2.9±1.2cm vs. 3.7±3.2 cm, p = 0.6), but with greater heterogeneity (T2W p = 0.02, post-contrast p = 0.01). Sporadic neurofibromas were larger (4.6±1.5cm vs. 3.4±2.4 cm, p = 0.03) than syndrome-related neurofibromas, also with greater heterogeneity (T2W p=0.03, post-contrast p=0.04). Additional tumors along an affected nerve were only observed with syndrome-related tumors). There was no difference in apparent diffusion coefficient values or presence of early perfusion between sporadic and syndrome-related tumors (p > 0.05). CONCLUSIONS: Although syndrome-related and sporadic schwannomas and neurofibromas overlap in their anatomic, diffusion and perfusion features, signal heterogeneity and presence of multiple lesions along a nerve are differentiating characteristics of syndrome-related tumors.

Surgery of Schwannoma in the upper limb - sensitivity and specificity of preoperative magnetic resonance imaging and relation between tumour size and symptoms.

BACKGROUND: Benign peripheral nerve tumours consist of different types, most commonly Schwannomas. Preoperative Magnetic Resonance Imaging (MRI) is commonly performed before surgery and Pathoanatomical Diagnosis (PAD) confirms the diagnosis. Our aims were to study the utility of MRI and the relation between tumour size and symptoms. METHODS: Retrospectively, patients, surgically treated for benign nerve tumours between 2008 and 2019, were identified and preoperative MRI, with measurement of tumour size, PAD, symptoms, peroperative details, and symptomatic outcomes of surgery, were analysed. RESULTS: The sensitivity and specificity to correctly identify Schwannomas with preoperative MRI were 85% and 50%, respectively, based on 30 Schwannomas and nine neurofibromas that were identified. Tumour size did not affect the presence of preoperative symptoms, but patients with sensory dysfunction at last follow-up had larger Schwannomas (p < 0.05). Symptoms as a palpable tumour, paraesthesia and pain improved by surgical excision (p < 0.001, p < 0.001 and p < 0.012, respectively), but sensory and motor dysfunction were common postoperatively. No malignant peripheral nerve sheath tumours (MPNST) were found. Using a surgical microscope, instead of only loop magnification, lowered the risk of perioperative nerve injuries (p < 0.05), but did not further diminish postoperative symptoms. CONCLUSIONS: Early and accurate diagnosis of Schwannomas is valuable for adequate presurgical preparation and prompt surgical intervention. Preoperative examination with MRI has a high sensitivity, but low specificity; although recent advancement in MRI technology indicates improvement in diagnostic precision. Surgical excision is preferably performed early in conjunction with symptomatic debut to improve outcome.

What is new in intraneural perineurioma?

Since the initial description of intraneural (IN) perineurioma in 1964, advances in the understanding of the clinical presentation, diagnostic imaging, pathologic features, and genetic underpinnings have changed how this pathology is managed. IN perineuriomas are rare, benign peripheral nerve sheath tumors, most frequently coming to clinical attention when patients present with painless, progressive weakness or sensory loss in adolescence or young adulthood. The gold standard of diagnosis has traditionally been with targeted tissue biopsy demonstrating "pseudo-onion bulb" formation with positive epithelial membrane antigen (EMA) staining. However, modern magnetic resonance imaging is allowing some patients to forgo biopsy. Recent genetic studies of IN perineuriomas have demonstrated common TRAF7 point mutations and rare NF2 mutations, which may present targets for diagnosis or therapy in the future. Current advances have allowed for us to provide improved patient counseling with informed understanding for various clinical scenarios. With the workup and diagnosis now clearly defined, the next frontier is for improving the lives of patients with IN perineuriomas through the interaction between restoration of functional deficits and advances in our understanding of the genetics of this entity.

Plexiform neurofibroma (Hamartoma) of the median nerve: A two-case report.

Plexiform neurofibroma is a benign peripheral nerve-sheath tumor, rarely involving major nerves of the extremities. In the literature, there are no clear treatment strategies for plexiform neurofibroma of major peripheral nerves. Our experience encountered two patients with plexiform neurofibroma of the median nerve, presenting with a palmar mass and symptoms of carpal tunnel compression. Preoperatively, plexiform neurofibroma was diagnosed on MRI and clinical examination. Both patients also experienced significant neurological deterioration, with finger numbness and increased nerve/tumor size. Potential malignant transformation was also considered. For these reasons, resection of the involved area of the nerve and repair were indicated. In both patients, intraoperative pathological diagnosis was plexiform neurofibroma. The 45-year-old male patient refused further surgery after carpal tunnel release, which was performed under axillary block. One year postoperatively, nerve compression symptoms decreased moderately. In the other patient, a 7-year-old boy, a significantly enlarged area of the median nerve was resected, and neurorrhaphy was performed. One year postoperatively, median nerve motor-sensory functions recovered completely. Four years postoperatively, no enlargement of the residual tumor was observed.

7T for clinical imaging of benign peripheral nerve tumors: preliminary results.

PURPOSE: MRI has become an essential diagnostic imaging modality for peripheral nerve pathology. Early MR imaging for peripheral nerve depended on inferred nerve involvement by visualizing downstream effects such as denervation muscular atrophy; improvements in MRI technology have made possible direct visualization of the nerves. In this paper, we share our early clinical experience with 7T for benign neurogenic tumors. MATERIALS: Patients with benign neurogenic tumors and 7T MRI examinations available were reviewed. Cases of individual benign peripheral nerve tumors were included to demonstrate 7T MRI imaging characteristics. All exams were performed on a 7T MRI MAGNETOM Terra using a 28-channel receive, single-channel transmit knee coil. RESULTS: Five cases of four pathologies were selected from 38 patients to depict characteristic imaging features in different benign nerve tumors and lesions using 7T MRI. CONCLUSION: The primary advantage of 7T over 3T is an increase in signal-to-noise ratio which allows higher in plane resolution so that the smallest neural structures can be seen and characterized. This improvement in MR imaging provides the opportunity for more accurate diagnosis and surgical planning in selected cases. As this technology continues to evolve for clinical purposes, we anticipate increasing applications and improved patient care using 7T MRI for the diagnosis of peripheral nerve masses.

Sporadic hemangioblastoma of cauda equina: A case-report and brief literature review / Hemangioblastoma esporádico de cauda equina: aporte de un caso y breve revisión de la literatura

Hemangioblastomas are rare lesions accounting for 1–5% of all spinal cord tumors and are mostly associated with von Hippel–Lindau syndrome. Localization in the cauda equina is uncommon. In this manuscript we aim to describe a rare case of sporadic intradural extramedullary hemangioblastoma of the cauda equina and present a literature review. A systematic research was performed on Pubmed, MEDLINE, and Google Scholar, using as keywords “spinal hemangioblastoma” and “cauda equina tumors”. The previous literature is integrated by the description of the present case. A 49 year-old female, presented on August 2020 to our institution suffering from claudication neurogena, right sciatica and paraesthesia in right L5 radicular dermatome for more than 3 months. Neurological examination revealed hypoesthesia on right L5 dermatome and weakness of right anterior tibialis muscle. An MRI which showed an intradural mass at L1/2 level and an angiography that showing a nidus of serpiginous vessels inside the lesion. Microsurgical en bloc resection of lesion was performed with adjuvant neurophisological intra operative monitorings. Histological examination provided the diagnosis of hemangioblastoma. After surgery symptoms and neurological impairment gradually improved. A 10 months post-operative MRI showed no residual tumor. Although intradural extramedullary hemangioblastoma of the cauda equina without von Hippel–Lindau syndrome it is a rare pathological entity, this diagnosis must be taken in for cauda equina masses. Preoperative embolization is an option to minimize intraoperative bleeding. Radiosurgery seems to prevent recurrences when the tumor is not completely excised. Complete surgical removal of the lesion is usually possible and lead to a low likelihood of recurrence (AU)

Los hemangioblastomas son lesiones raras que representan del 1 al 5% de todos los tumores de la médula espinal y se asocian principalmente al síndrome de von Hippel-Lindau. La localización en la cauda equine es infrecuente. En este manuscrito nuestro objetivo es describir un caso raro de hemangioblastoma intradural extramedular esporádico de la cauda equina y presentar una revisión de la literatura. Se realizó una bùsqueda sistemática en Pubmed, MEDLINE y Google Scholar, utilizando como palabras clave «spinal hemangioblastoma» y «cauda equina tumors». Presentamos el caso clínico y se discute, y se compara con la literatura previamente publicada al respecto. Mujer de 49 años, se presentó en agosto del 2020 a nuestra institución. Los síntomas fueron claudicatio neurogena, ciática derecha y parestesia en dermatoma radicular L5 derecho durante más de 3 meses. El examen neurológico reveló hipoestesia en el dermatoma L5 derecho y debilidad del músculo tibial anterior derecho. La resonancia magnética mostró una masa intradural a nivel L1/2 y la angiografía mostró un nido de vasos serpiginosos dentro de la lesión. Se realizó una resección microquirúrgica en bloque de la lesión con monitorización intraoperatoria neurofisiológica adyuvante. El examen histológico proporcionó el diagnóstico de hemangioblastoma. Después de la cirugía, los síntomas y el deterioro neurológico mejoraron gradualmente. Una resonancia magnética 10 meses después de la operación no mostró tumor residual. Aunque el hemangioblastoma intradural extramedular de la cauda equine sin síndrome de von Hippel-Lindau es una entidad patológica poco frecuente, este diagnóstico debe tenerse en cuenta cuando una masa afecta a la cola de caballo. La embolización preoperatoria es una opción para minimizar el sangrado intraoperatorio. La radiocirugía parece prevenir las recurrencias cuando el tumor no se extirpa por completo (AU)

Post-traumatic glomus tumor of the left anterior supraclavicular nerve: a case report.

OBJECTIVES: Peripheral nerve glomus tumors are extremely rare and occur with typical symptoms of peripheral neuropathic pain. Clinicians hardly consider this entity when faced with the swelling of a peripheral nerve and the diagnosis is reached only with histological examination. Nerves of limbs are usually affected and the solid glomus tumor is the most frequent histological variant. CASE DESCRIPTION: A 55-year-old man presented with a glomus tumor of the anterior supraclavicular nerve of the left cervical plexus, misdiagnosed clinically and radiologically as neuroma. Despite the preoperative suspicion and the intraoperative appearance, the histological examination revealed a glomus tumor with a prevalent muscular component, a glomangiomyoma. Once the tumor was removed, pain regressed completely. CONCLUSIONS: Because of its rarity, pre-operative diagnosis of glomus tumors is still a challenge, especially when arising from peripheral nerves. In the presence of chronic localized neuroma-type pain and sensitivity, glomus tumors should be considered in the pool of differential diagnosis, even if the imaging is not conclusive.

Plexal intraneural perineurioma: an analysis of the clinicoradiologic presentation of this rare variant.

PURPOSE: Intraneural (IN) perineurioma is a rare benign peripheral nerve sheath tumor, typically presenting as a painless, progressive mononeuropathy in adolescents. A rare plexal variant has been described, although there are little data describing its clinicoradiologic features. Herein, we present the largest case series of plexal IN perineuriomas reported in the literature. METHODS: Electronic medical records (EMR) from 1990 to 2022 from a single academic institution were reviewed for a diagnosis of IN perineurioma involving the brachial or lumbosacral plexus. This identified 18 patients, of which 17 had available MR imaging. We reviewed the EMR for demographics, clinical presentation, imaging characteristics, and surgical outcomes. RESULTS: Eighteen patients were identified. Most patients were male (11/18, 61%) and first developed symptoms at the age of 9.6 years (range 7 months to 55 years). Diagnosis occurred on average at the age of 22 years (4-57 years), which is significantly earlier than distal IN perineurioma (p = 0.0096). All patients (100%, 17/17) presented with motor polyneuropathy and muscular atrophy in multiple nerve distributions, with associated sensory loss (12/17, 71%). Most plexal lesions occurred in the brachial plexus (66%, 12/18). Five (29%, 5/17) patients presented with a hand/foot discrepancy, and 5 patients (29%) had a limb length discrepancy. Five patients underwent tendon transfer, of which two had failure of tendon transfer at most recent follow-up (50%, 2/4) due to progression of neurologic loss affecting the donors. Of patients managed nonoperatively, 87% of patients (6/7) with follow-up information demonstrated disease progression with worsening motor function or sensory loss, and 2 patients demonstrated progression on imaging at most recent follow-up. CONCLUSIONS: Plexal perineurioma represents an uncommon variant of IN perineurioma that presents as a progressive motor and sensory polyneuropathy in childhood or early adolescence. Surgical management remains controversial, and tendon transfer tends to result in poor long-term surgical outcomes.

Ultrasonography of peripheral nerve tumours: a case series.

BACKGROUND: Peripheral nerve tumours (PNTs) are rare, but important cause of peripheral nerve dysfunction. The aim of the study was to present a series of consecutive patients with PNTs evaluated in authors' ultrasonography (US) practice. PATIENTS AND METHODS: The electronic medical records of patients with PNTs examined at our US laboratory from February 2013 to May 2020 were retrospectively reviewed. Data on gender, age, clinical features, PNT location, electrodiagnostic (EDx) features and US findings were collected. RESULTS: In the analyzed period 2845 patients were examined in our US laboratory. From these 15 patients (0.5%) with PNTs were identified. Four of them (3 with confirmed neurofibromatosis) had multiple PNTs. Half of patients (53%) presented with features of peripheral nerve damage, and others with palpable mass or pain. The most often involved nerve was ulnar (36%). PNT cross sectional areas varied from 24 mm2 to 1250 mm2 (median, 61 mm2). Based in 5 patients on histological and in remaining patients on US features, schwannoma was diagnosed in 40%, neurofibroma in 27%, and perineurioma in 27% of patients. CONCLUSIONS: As in previous reports, PNTs in our series presented with neurological symptoms, palpable mass or pain. In contrast to other focal neuropathies, particularly nerves with schwannomas, in spite of their large thickening, often demonstrated well preserved function. Adding US to our clinical practice, enabled us to diagnose these rare peripheral nerve lesions that we missed before.

Ultrasound and MR imaging of peripheral nerve tumors: the state of the art.

Peripheral nerve sheath tumors are a heterogeneous subgroup of soft tissue tumors that either arise from a peripheral nerve or show nerve sheath differentiation. On imaging, direct continuity with a neural structure or location along a typical nerve distribution represents the most important signs to suggest the diagnosis. Ultrasound and magnetic resonance imaging are the best modalities to evaluate these lesions. First, it is necessary to differentiate between a true tumor and a non-neoplastic nerve condition such as a neuroma, peripheral nerve ganglion, intraneural venous malformation, lipomatosis of nerve, or nerve focal hypertrophy. Then, with a combination of clinical features, conventional and advanced imaging appearances, it is usually possible to characterize neurogenic tumors confidently. This article reviews the features of benign and malignant peripheral nerve sheath tumors, including the rare and recently described tumor types. Furthermore, other malignant neoplasms of peripheral nerves as well as non-neoplastic conditions than can mimick neurogenic tumor are herein discussed.

MR Neurography of Peripheral Nerve Tumors and Tumor-Mimics.

Tumors of the peripheral nervous system can range from benign, such as neurofibroma or schwannoma, to malignant peripheral nerve sheath tumors (MPNSTs). Magnetic resonance neurography (MRN) enables the distinction of benign peripheral nerve sheath tumors (PNSTs) from MPNSTs. In addition, MRN allows for the assessment of anatomical extent if operative management is planned and can help determine a surveillance strategy. Occasionally, tumor mimics such as traumatic neuromas can masquerade as peripheral nerve tumors. This review will illustrate the spectrum of peripheral nerve tumors and their mimics, emphasizing key distinguishing features to provide optimal MRN interpretation that enhances diagnostic thinking and therapeutic management.

Magnetic Resonance Imaging of Nerve Tumors.

Nerve tumors are uncommon soft tissue neoplasms predominantly arising from peripheral nerve sheath and Schwann cells. We review the manifestations of benign peripheral nerve sheath tumors, concentrating on distinguishing imaging features of schwannomas versus neurofibromas with an emphasis on treatment implications. Nevertheless, there is often an overlap between the imaging presentation of these two conditions, making the accurate radiologic diagnosis challenging. Therefore, tissue sampling is often needed for a definitive histologic diagnosis. Treatment planning largely depends on symptoms, location of the lesion, and underlying risk factors. Three major syndromes, neurofibromatosis type 1, type 2, and schwannomatosis, predispose patients to peripheral nerve sheath tumors (PNSTs), with particular concern about the malignant subtype expression. In patients with suspected PNSTs, correlation of imaging findings with clinical findings and genetic tests is helpful for a more accurate diagnosis and disease management. Some imaging features on magnetic resonance imaging and fluorodeoxyglucose-positron emission tomography can be helpful to differentiate malignant from benign subtypes.

Presurgical Perspective and Postsurgical Evaluation of Morton's Neuroma and Other Nerve Lesions.

Magnetic resonance imaging (MRI) is a robust method used for both preoperative and postoperative evaluation of Morton's neuroma and other neural lesions. MRI is used to confirm the diagnosis and for precise localization, estimation of outcome, and differential diagnoses. The differential diagnoses include mechanically induced plantar plate ruptures with associated Morton's neuroma-like tumors in the intermetatarsal/interdigital spaces; mechanical fibrosis cushion formations and pseudo bursae in the plantar foot adipose tissue; rheumatologic affections, such as rheumatoid nodules, gouty nodules, and intermetatarsal bursitis; and lastly the tenosynovial giant cell tumor (formerly called pigmented villonodular synovitis). In the postoperative evaluation after resection of Morton's neuroma, the same differential diagnoses must be considered as in the preoperative evaluation. Similarly, a high prevalence (up to 25%) of asymptomatic Morton's neuroma-like findings in the intermetatarsal and interdigital spaces should be kept in mind when interpreting postoperative recurrent forefoot pain after Morton's neuroma resection.

Saphenous nerve schwannoma as a cause of vascular claudication - case report and review of the literature.

Schwannomas are peripheral nerve tumours that are uncommon. They typical present with a palpable mass, pain or neurological changes. We describe a saphenous nerve schwannoma compressing the superficial femoral artery and causing vascular claudication. We also review the literature.