Telltale signs of peripheral neurogenic tumors on magnetic resonance imaging

Pictorial Review of Soft Tissue Lesions with Calcification

Calcifications in soft tissue tumors present critical diagnostic challenges in musculoskeletal imaging. Their presence and morphology can provide key clues for differentiating benign from malignant lesions, influencing both prognosis and management strategies. This pictorial review aims to explore the imaging characteristics, patterns, and implications of soft tissue calcifications, with a focus on distinguishing between benign and malignant soft tissue tumors based on the World Health Organization classification. A systematic evaluation of imaging findings in various soft tissue tumor subtypes, including adipocytic, smooth muscle, vascular, chondro-osseous, and tumors of uncertain differentiation, is presented. Additionally, non-neoplastic causes of soft tissue calcifications, such as metabolic and inflammatory conditions, are reviewed for comprehensive differential diagnosis. Our review shows that the presence, distribution, and morphology of calcifications, such as stippled, punctate, coarse, and amorphous patterns, play a crucial role in tumor characterization. Some important examples are phleboliths, which strongly suggest a benign hemangioma, while dystrophic calcification is more commonly associated with malignant entities such as synovial sarcoma and dedifferentiated liposarcoma. Peripheral calcifications with zonal distribution are characteristic of myositis ossificans, whereas central dense calcifications may indicate extra-skeletal osteosarcoma. The review also discusses the significance of calcifications in non-neoplastic conditions, such as calcific tendinitis, tumoral calcinosis, and metabolic diseases, which can mimic soft tissue tumors. Recognizing the imaging characteristics of soft tissue calcifications is essential for accurate tumor classification and appropriate clinical management. This review highlights the importance of integrating radiologic findings with clinical and histopathological data to avoid misdiagnosis and unnecessary interventions.

Peripheral Nerve Injuries: Preoperative Evaluation and Postoperative Imaging

Imaging plays an important role in evaluating peripheral nerves. In the preoperative setting, imaging helps overcome pitfalls of electrodiagnostic testing and provides key anatomical information to guide surgical management. In the postoperative setting, imaging also offers key information for treating physicians, although it comes with several challenges due to postsurgical changes and alteration of normal anatomy. This article reviews our approach to peripheral nerve imaging, including how we use imaging in the pre- and postoperative setting for several common indications.

Schwannomas of the upper limb: Clinical presentation, preoperative management and outcomes of surgical treatment

INRODUCTION

Schwannomas are the most common tumors of the peripheral nervous system. Surgical eradication with excision or enucleation is the treatment for symptomatic and large schwannomas.

Intramuscular mesenchymal chondrosarcoma surrounded by a split fat sign mimicking a benign lesion

Mesenchymal chondrosarcoma (MCS) is an aggressive malignant mesenchymal tumour of uncertain differentiation. This is rare, accounting for 2%-4% of chondrosarcomas. Its peak incidence is in the second and third decades, though it can occur at any age. These tumours show a widespread distribution, mainly in bone, but with approximately 40% affecting somatic soft tissue. We present a case of MCS arising within the soleus muscle. The lesion was surrounded by a split-fat sign/fatty rind which is a typical feature of peripheral nerve sheath tumours or other benign intramuscular tumours. However, percutaneous biopsy showed MCS. We highlight how perilesional fat is not exclusive to benign intramuscular lesions and, although much less common, can be associated with malignant lesions. This is, to the best of our knowledge, the first reported case of MCS presenting with a split-fat sign at MRI.

A Recurrent Schwannoma in the Left Distal Ulnar Nerve

While peripheral nerve schwannomas have a relatively low incidence, schwannomatosis, the condition in which one forms multiple recurring schwannomas, is an even rarer phenomenon and can be hard to detect given its ability to mimic other conditions. We report a case of a 35-year-old male who presented with a mass in his left wrist and forearm, volar pain in his forearm, and numbness in his fingers. Magnetic resonance imaging (MRI) revealed a bilobed heterogeneous neural sheath tumor in the distal left ulnar nerve. The tumor was resected including extensive internal neurolysis using a Zeiss operative microscope. Post-operative biopsy confirmed an encapsulated schwannoma. The patient did well initially but developed worsening pain in his forearm and weakness. He had persistent paresthesias in the ulnar nerve distribution. He underwent a repeat MRI almost one year later, which showed thickening of the ulnar nerve proximal to the area of resection with an 8.5 mm hyperintense nodule. The patient underwent a subsequent resection with extensive neurolysis, which confirmed that the mass was a benign non-invasive schwannoma. At six weeks post-surgery, the patient's forearm pain was significantly improved and his range of motion returned to baseline. Our case demonstrates the importance of post-operative follow-up in schwannomas with appropriate imaging if symptoms persist or recur.

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.

Schwannoma as Extraspinal Swelling Over the Thoracolumbar Region: A Tumor at a Rare Site

This case report describes an unusual presentation of schwannoma, a typically benign and solitary tumor originating from Schwann cells in peripheral nerves. While the literature on extraspinal schwannomas is limited, this report discusses the case of a 21-year-old female with complaint of a back swelling persisting for two years, causing discomfort during sleep. The oval-shaped swelling, measuring 7x6 cm, was located over the T11-T12-L1 vertebrae, with normal overlying skin, pinchable hardness, and fixation to the vertebrae. The patient had no history of pain or weakness in the lower limbs. Fine-needle aspiration cytology (FNAC) yielded inconclusive results. X-ray imaging of the thoracolumbar spine revealed a soft tissue shadow over the T11-T12-L1 vertebrae. The patient underwent complete surgical excision through a vertical incision, emphasizing the importance of preoperative imaging for accurate diagnosis, optimal surgical planning, and ensuring procedural safety.

Neurofibroma Involving a Bifid Median Nerve in a Pediatric Patient: A Case Report

Neurofibromas are benign peripheral nerve sheath tumors that typically develop within cutaneous nerve branches but can involve major nerves as well. They can be sporadic or associated with neurofibromatosis type 1. In this report, we describe the surgical treatment of a pediatric patient with neurofibromatosis type 1 presenting with a neurofibroma of a bifid median nerve. Involvement of the median nerve was not evident on preoperative examination or imaging, therefore altering the risk-benefit ratio of the procedure. After bifid nerve involvement was identified intraoperatively, the patient's parents were counseled on the risks and benefits of surgical excision before resuming the case. Ultimately, the neurofibroma was resected, and the patient experienced no neurological deficits after surgery.

Primary Pathology of the Parapharyngeal Space

The radiologically defined parapharyngeal space is a distinct location on cross-sectional imaging and is often described based on its displacement or invasion by tumors or other pathologies in adjacent spaces; however, there are multiple primary pathologic entities of the parapharyngeal space, which are often forgotten. Recognizing that a lesion is arising from the parapharyngeal space is important in generating an accurate differential diagnosis that will guide management.

Vascular leiomyoma of the thigh: Classic presentation of a rare tumor with imaging and pathology correlation

We report a case of a vascular leiomyoma arising from the superficial femoral artery presenting as a non-painful thigh mass in a 55-year-old woman. Leiomyomas typically arise from the uterus and gastrointestinal tract, and rarely arise from vessels. We present this case to emphasize that although extremity leiomyomas are rare, they should be considered if there is a soft tissue mass abutting a vessel. Radiologists should be familiar with the imaging features associated with vascular leiomyomas.

Relationship between magnetic resonance imaging findings and histological grade in spinal peripheral nerve sheath tumors in dogs

BACKGROUND

Peripheral nerve sheath tumors (PNSTs) are a group of neoplasms originating from Schwann cells or pluripotent cell of the neural crest. Therapeutic options and prognosis are influenced by their degree of malignancy and location.

HYPOTHESIS/OBJECTIVES

Identify magnetic resonance imaging (MRI) features predictive of PNST histologic grade.

ANIMALS

Forty-four dogs with histopathological diagnosis of spinal PNSTs and previous MRI investigation.

METHODS

A multicenter retrospective study including cases with (a) histopathologic diagnosis of PNST and (b) MRI studies available for review. Histologic slides were reviewed and graded by a board-certified pathologist according to a modified French system (FNCLCC) for grading soft tissue sarcomas. The MRI studies were reviewed by 2 board-certified radiologists blinded to the grade of the tumor and the final decision on the imaging characteristics was reached by consensus. Relationships between tumor grade and histological and MRI findings were assessed using statistical analysis.

RESULTS

Forty-four cases met inclusion criteria; 16 patients were PNSTs Grade 1 (low-grade), 19 were PNSTs Grade 2 (medium-grade), and 9 were PNSTs Grade 3 (high-grade). Large volume (P = .03) and severe peripheral contrast enhancement (P = .04) were significantly associated with high tumor grade. Degree of muscle atrophy, heterogeneous signal and tumor growth into the vertebral canal were not associated with grade.

CONCLUSIONS AND CLINICAL IMPORTANCE

Grade of malignancy was difficult to identify based on diagnostic imaging alone. However, some MRI features were predictive of high-grade PNSTs including tumor size and peripheral contrast enhancement.

Case report of a giant cell tumor of the carotid sheath

Giant cell tumor of the soft tissue (GCTST) is a neoplasm with low malignant potential and typically affects the trunk and extremities. Herein, we present a case of a palpable right neck mass diagnosed as a GCTST of the carotid sheath in a 38-year-old woman. A review of the imaging characteristics as well as of the differential diagnoses of primary neoplasms of the carotid space is presented.

Sinonasal and Infratemporal Schwannoma: Rare Case Report with Literature Review

Schwann cells are responsible for the production of the myelin sheath around the axons of the peripheral nervous system. Benign neoplasms which originate from Schwann cells are hence termed Schwannomas or Neurilemmomas. They present as slow-growing, solitary, encapsulated, benign masses usually in association with nerve trunks. Schwannomas are relatively rare tumors with 25-45% occurring in the head and neck region. These case reports aim to describe the presentations, work-up, and treatment of two patients with head and neck schwannoma in atypical locations. Both patients had a history of gradually increasing swelling, the first originating from the sino-nasal region and the second from the temporal/ infratemporal region. Complete surgical excision of the tumor was done in both cases with no reported recurrence at 18 months follow-up. The final diagnosis was made based on histopathology and immunohistochemistry findings. Schwannomas often present a diagnostic dilemma and should be considered a possibility in all head and neck tumors. Recurrence is rare.

Beyond the abdominal and pelvic cavity: abdominal wall and spinal "Aunt Minnies"

Abdominal wall and spinal soft tissue findings are frequently encountered on CT or MR imaging of the abdomen and pelvis. Many of these entities have specific imaging findings, for which a definitive diagnosis can be made without the need for further work up. These abdominal wall and spinal findings may be diagnostically challenging for sub-specialized abdominal radiologists who are unfamiliar with their appearance and appropriate management. This review article describes and illustrates pathognomonic or characteristic abdominal wall and spinal pathologies, which reside outside the abdominopelvic cavity. The cases selected all have findings that allow a confident diagnosis without further imaging or intervention. The cases presented include myonecrosis, intramuscular abscess, myositis, iliopsoas bursitis, Morel-Lavallée lesion, hydrocele of canal of Nuck, Klippel Trenaunay Weber syndrome, neurofibroma with target sign, perineural cysts, filum terminale lipoma, calvarial bone flap, transverse rectus abdominis muscle (TRAM) flap, liposuction, and hidradenitis suppurativa, among others. Although not all-encompassing, this paper will help abdominal radiologists to accurately diagnose a variety of abdominal and pelvic extra-cavitary soft tissue pathologies by identifying key radiologic findings.

Benign soft tissue tumours of the foot & ankle: A pictorial review

The purpose of this pictorial review is to aid the clinician in distinguishing different benign lesions within the foot and ankle. We discuss the typical clinical and radiological findings as well as management options for intra and extra-compartmental lesions. Differentiation between sarcoma and benign lesions is imperative when presented with any mass in the foot or ankle.

Investigation of Ultrasound Parameters for the Differential Diagnosis of Malignant and Benign Peripheral Nerve Sheath Tumors

OBJECTIVES

The objectives were to identify the key features of malignant and benign peripheral nerve sheath tumors (PNSTs) and determine a strategy for differentiating them using sonography.

METHODS

Forty-six malignant peripheral nerve sheath tumors (MPNSTs) and 83 benign peripheral nerve sheath tumors (BPNSTs) confirmed by pathology from April 2010 to July 2021 were included. The general data and grayscale and color Doppler ultrasonic manifestations were compared between the two groups. We used single factor, multifactor, and area under the receiver operating characteristic (ROC) curve analyses to extract significant malignant risk factors and then established a scoring system with these factors.

RESULTS

The significant variables identified in univariate analysis (P < .05) were maximum diameter, location, shape, boundary, encapsulation, echogenicity, texture pattern, calcification, entering or exiting nerve, and vascularity. Shape, boundary and vascularity were significant risk factors, and a scoring system was established. The area under the ROC curve (0.925) confirmed the usefulness of the scoring system for differentiating MPNSTs and BPNSTs.

CONCLUSIONS

Ultrasonography is an effective method for differentiating MPNSTs from BPNSTs.

The Varied Presentations of Sinonasal Region Schwannomas: Apropos of Four Cases

Schwannomas of the sinonasal compartment are rare benign neoplasms of peripheral nerve sheath origin and constitute ~ 4% of all head and neck schwannomas. The presentation may simulate a range of benign and intermediate grade pathologies. Management involves surgical excision via open or endoscopic approach. To describe the clinico-epidemiological characteristics and surgical outcomes in sinonasal region schwannoma patients operated at our institute. The study is a descriptive case series of patients with sinonasal region schwannomas treated at our institution. A retrospective search of electronic database of the Department of ENT and Head and Neck Surgeries and Department of Pathology was conducted from January 2013 to January 2019. The various demographic and clinical details of the patients were extracted. A total of four patients operated for sinonasal region schwannoma were identified. The involved sites were nasal dorsum, nasal cavity, pterygopalatine fossa and infratemporal fossa. The mild, non-specific symptoms resulted in patients ignoring their symptoms for a while initially and presenting late. The nasal dorsum lesion was revealed as a surprise during open rhinoplasty for correction of nasal deformity. Complete excision was achieved in all the cases and no recurrence has been noticed during the follow up (varying from 6 months to 6 years) till date. The diverse clinical manifestations and approaches to the treatment of schwannomas in this specific region are discussed. The surgical excision is the standard of care in dealing with these neoplasms. This series highlights the rarity of this pathology in the sinonasal area, diagnostic surprises and the decision making to choose the correct surgical approach for complete excision. Once excised completely, recurrence is not expected.

Nerve Imaging in the Wrist

Neuropathic symptoms involving the wrist are a common clinical presentation that can be due to a variety of causes. Imaging plays a key role in differentiating distal nerve lesions in the wrist from more proximal nerve abnormalities such as a cervical radiculopathy or brachial plexopathy. Imaging complements electrodiagnostic testing by helping define the specific lesion site and by providing anatomical information to guide surgical planning. This article reviews nerve anatomy, normal and abnormal findings on ultrasonography and magnetic resonance imaging, and common and uncommon causes of neuropathy.

A Rare Case Report on Neurilemmoma of the Superficial Peroneal Nerve and a Review of the Literature

Neurilemmoma is a form of nerve tumor that develops from the nerve sheaths. It is a slow-growing tumor with a rare malignant transformation. It has an incidence rate of less than 1% in lower limbs and its origin in the superficial peroneal nerve is an extremely rare occurrence. In this report, we present a case of neurilemmoma of the superficial peroneal nerve in a 67-year-old male who presented with complaints of pain and swelling at the lateral aspect of the leg. The swelling was enucleated while preserving the main nerve trunk. The patient was found to be asymptomatic after a two-year postoperative period.

Machine Learning Approach to Differentiation of Peripheral Schwannomas and Neurofibromas: A Multi-Center Study

BACKGROUND

Non-invasive differentiation between schwannomas and neurofibromas is important for appropriate management, preoperative counseling, and surgical planning, but has proven difficult using conventional imaging. The objective of this study was to develop and evaluate machine learning approaches for differentiating peripheral schwannomas from neurofibromas.

METHODS

We assembled a cohort of schwannomas and neurofibromas from 3 independent institutions and extracted high-dimensional radiomic features from gadolinium-enhanced, T1-weighted MRI using the PyRadiomics package on Quantitative Imaging Feature Pipeline. Age, sex, neurogenetic syndrome, spontaneous pain, and motor deficit were recorded. We evaluated the performance of 6 radiomics-based classifier models with and without clinical features and compared model performance against human expert evaluators.

RESULTS

107 schwannomas and 59 neurofibroma were included. The primary models included both clinical and imaging data. The accuracy of the human evaluators (0.765) did not significantly exceed the no-information rate (NIR), whereas the Support Vector Machine (0.929), Logistic Regression (0.929), and Random Forest (0.905) classifiers exceeded the NIR. Using the method of DeLong, the AUC for the Logistic Regression (AUC=0.923) and K Nearest Neighbor (AUC=0.923) classifiers was significantly greater than the human evaluators (AUC=0.766; p = 0.041).

CONCLUSIONS

The radiomics-based classifiers developed here proved to be more accurate and had a higher AUC on the ROC curve than expert human evaluators. This demonstrates that radiomics using routine MRI sequences and clinical features can aid in differentiation of peripheral schwannomas and neurofibromas.

Morphology of the entering and exiting nerve as a differentiating feature of benign from malignant peripheral nerve sheath tumours of the brachial plexus

OBJECTIVE

To identify if morphology of the entering and exiting nerve involved by a nerve sheath tumour in the brachial plexus can help differentiate between benign (B) and malignant (M) peripheral nerve sheath tumours (PNSTs).

MATERIALS AND METHODS

Retrospective review of 85 patients with histologically confirmed primary PNSTs of the brachial plexus over a 12.5-year period. Clinical data and all available MRI studies were independently evaluated by 2 consultant musculoskeletal radiologists blinded to the final histopathological diagnosis assessing for maximal lesion dimension, visibility and morphology of the entering and exiting nerve, and other well-documented features of PNSTs.

RESULTS

The study included 47 males and 38 females with mean age 46.7 years (range, 8-81 years). There were 73 BPNSTs and 12 MPNSTs. The entering nerve was not identified in 5 (7%), was normal in 17 (23%), was tapered in 38 (52%) and showed lobular enlargement in 13 (18%) BPNSTs compared with 0 (0%), 0 (0%), 2 (17%) and 10 (83%) MPNSTs respectively. The exiting nerve was not identified in 5 (7%), was normal in 20 (27%), was tapered in 42 (58%) and showed lobular enlargement in 6 (8%) BPNSTs compared with 4 (33%), 0 (0%), 2 (17%) and 6 (50%) MPNSTs respectively. Increasing tumour size, entering and exiting nerve morphology and suspected MRI diagnosis were statistically significant differentiators between BPNST and MPNST (p < 0.001). IOC for nerve status was poor to fair but improved to good if normal/tapered appearance were considered together with improved specificity of 81-91% for BPNST and sensitivity of 75-83%.

CONCLUSIONS

Morphology of the adjacent nerve is a useful additional MRI feature for distinguishing BPNST from MPNST of the brachial plexus.

Malignant Peripheral Nerve Sheath Tumor in an Army Reservist With Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant condition affecting 1 in 3,500 people resulting from an NF1 gene mutation that encodes the nonfunctional protein neurofibromin mutant. Neurofibromin is a negative regulator of RAS signaling involved in cell survival and proliferation. NF1 typically presents at birth or in early childhood with multiple light brown (café au lait) spots and axillary freckling. With age, patients may develop scattered neurofibromas as well as additional neurological and malignant abnormalities. Additionally, the nonfunctional protein neurofibromin mutant may be involved in the pathogenesis of peripheral malignant nerve sheath tumors, which is a rare and life-threatening complication of NF1. While a disqualifying condition for military duty, it may not initially be clinically apparent until complications develop. Here, we present a case of malignant peripheral sheath in an U.S. Army African American reservist with NF1 in whom cutaneous manifestations of NF1 such as café au lait spots and axillary freckling were not identified on the initial military entrance processing examination.

Intra-articular Synovial Hemangioma: A Rare Cause of Knee Pain and Swelling

Synovial hemangioma is a rare intra articular lesion and it has several more common differentials. Therefore, our main objective is to consider the possibility of hemangioma in any intra-articular mass to prevent diagnostic delay of unnoticed or untreated hemangioma occurring within the knee joint. Ultrasound can be useful method in assessing the lesions. Surgical excision is the definitive treatment for such lesions.

Nerve Sheath Myxoma in the Lower Extremity: A Rare Case with Description of Magnetic Resonance Imaging and Sonographic Findings

BACKGROUND This report is of a nerve sheath myxoma presenting as a slow-growing mass in the back of the left ankle of a 36-year-old man that was investigated by ultrasound and magnetic resonance imaging (MRI) before the diagnosis was confirmed by histopathology. CASE REPORT We report a nerve sheath myxoma of the ankle in a 36-year-old man. The palpable abnormality was falsely assumed to be a ganglion cyst prior to advanced imaging. Magnetic resonance imaging demonstrated a lobular mass with high T2 and intermediate T1 signal as well as moderate enhancement. T2 sequences also demonstrated distinctive internal septae. These internal septae were also noted on sonographic evaluation prior to biopsy. The patient was treated with surgical excision, and pathologic analysis showed myxoid nodules with loose arrangements of spindled cells separated by fibrous septae. S-100 protein and glial fibrillary acidic protein positivity by immunohistochemistry staining was demonstrated. Follow-up imaging at 12 months showed no evidence of tumor recurrence. CONCLUSIONS This case highlights that while nerve sheath myxomas are rare tumors, they should be considered in cases of cutaneous soft-tissue masses with myxoid imaging features. Ultrasound and magnetic resonance imaging features of thin internal septae may be present and correspond well with the unique histopathological characteristics of these lesions. This report shows the importance of imaging of peripheral soft-tissue masses, including ultrasound and MRI, which can identify localized and benign features and the solid, cystic, and myxoid areas, which were characteristic in this case of benign nerve sheath myxoma.

Solitary neurofibroma of the larynx: a diagnostic challenge

Solitary neurofibromas of the larynx are extremely rare, with a total of 15 cases described in the literature. Nonetheless, acquaintance with this diagnosis is important, as misdiagnoses can have negative consequences. Presenting symptoms are non-specific and depend on tumour size and location. As well-defined submucosal masses with a broad differential diagnosis, they remain a clinical and radiological challenge. While some characteristics might favour a benign nature and subtle signs might help narrow the differential diagnosis, imaging alone is not sufficient for differentiation and definitive diagnosis requires a biopsy. Complete surgical resection and long-term follow-up is indicated. We share our experience on a case of a solitary laryngeal neurofibroma in a middle-aged woman, presenting with a large well-defined paraglottic lesion.

The safety of primary surgical excision of small deep indeterminate musculoskeletal soft tissue masses

OBJECTIVE

To determine the suitability of primary excision of small indeterminate deep soft tissue masses presenting to a tertiary musculoskeletal oncology service.

METHODS AND MATERIALS

Review of all patients referred to a specialist musculoskeletal oncology service over a 20-month period with a deep indeterminate soft tissue mass by non-contrast MRI criteria that was recommended for primary surgical excision due to relatively small size (<30 mm). Data collected included age, gender, site and maximal size of the lesion, and final histological diagnosis for excised lesions.

RESULTS

85 patients were included, mean lesion size being 12 mm (range 5-29 mm). Primary surgical resection had been undertaken in 69 cases (81.2%) by the conclusion of data collection, 36 males and 33 females with mean age of 45.6 years (range 11-80 years). Of these, 11 cases (15.9%) were non-neoplastic, 53 (76.8%) were benign, 1 (1.4%) was intermediate grade, while 4 (5.8%) were malignant including 3 synovial sarcomas. Two of these were treated with re-excision of the tumour bed showing no residual disease, with no evidence of local recurrence at a mean of 10.7 months post-excision.

CONCLUSION

Primary surgical excision of small deep soft tissue masses that are indeterminate by non-contrast MRI criteria is considered a safe procedure when undertaken in a specialist musculoskeletal oncology service, with only 4 of 69 cases (5.8%) being malignant.

ADVANCES IN KNOWLEDGE

Small indeterminate deep soft tissue masses can safely be treated with primary excision in the setting of a specialist musculoskeletal oncology service.

Primary synovial sarcomas in the paediatric and young adult population: A pictorial review

PURPOSE

To present a pictorial essay of paediatric primary synovial sarcomas from common and less documented anatomical locations. To review the literature for the imaging characteristics and prognostic factors of this rare but important childhood malignancy.

METHOD

24 primary synovial sarcoma cases (17 male, 7 female with an age range 4-21 years) were reviewed in a collaborative effort between St Jude Children's Research Hospital and Great Ormond Street Hospital for Children. Images from 19 cases were selected for inclusion, to demonstrate the spectrum of appearances across imaging modalities, in a range of different anatomical locations (upper limb, lower limb, chest/abdomen/pelvis, and head and neck). A literature review depicting the typical radiological features and the prognostic significance of these features, was also conducted.

RESULTS AND CONCLUSIONS

Primary synovial sarcoma can occur in any anatomical location, but typically within the extremities and often in close association with joints. Rarer anatomical locations described in our essay include the gastrohepatic ligament and femoral nerve sheath. We detail the salient imaging characteristics, including the T2 'triple signal' pattern which is believed to be highly specific for this particular sarcoma and in many cases predicts a poor outcome. Other poor prognostic factors include haemorrhage, lack of calcification and tumour size >10 cm. A broad range of radiological appearances are described, and in some cases related to anatomical position and size, however the presence of a soft tissue mass close to a joint in a young patient are suggestive of this diagnosis.

Peripheral nerve sheath tumor: differentiation of malignant from benign tumors with conventional and diffusion-weighted MRI

OBJECTIVES

To evaluate potential of conventional MRI and diffusion-weighted imaging (DWI) for differentiating malignant from benign peripheral nerve sheath tumors (PNSTs).

METHODS

Eighty-seven cases of malignant or benign PNSTs in the trunk or extremities that underwent conventional MRI with contrast enhancement, DWI, and pathologic confirmation between Sep. 2014 and Dec. 2017 were identified. Of these, 55 tumors of uncertain nature on MRI were included. Tumor size, signal, and morphology were reviewed on conventional MRI, and apparent diffusion coefficient (ADC) values of solid enhancing portions were measured from DWI. Patient demographics, MRI features, and ADC values were compared between benign and malignant tumors, and robust imaging findings for malignant peripheral nerve sheath tumors (MPNSTs) were identified using multivariable models.

RESULTS

A total of 55 uncertain tumors consisted of 18 malignant and 37 benign PNSTs. On MRI, tumor size, margin, perilesional edema, and presence of split fat, fascicular, and target signs were significantly different between groups (p < 0.05), as were mean and minimum ADC values (p = 0.002, p < 0.0001). Most inter-reader agreement was moderate to excellent (κ value, 0.45-1.0). The mean ADC value and absence of a split fat sign were identified as being associated with MPNSTs (odds ratios = 13.19 and 25.67 for reader 1; 49.05 and 117.91 for reader 2, respectively). The C-indices obtained by combining these two findings were 0.90 and 0.95, respectively.

CONCLUSIONS

Benign and malignant PNSTs showed different features on MRI and DWI. A combination of mean ADC value and absence of split fat was excellent for discriminating malignant from benign PNSTs.

KEY POINTS

• It is important to distinguish between malignant peripheral nerve sheath tumors (MPNSTs) and benign peripheral nerve sheath tumors (BPNSTs) to ensure an appropriate treatment plan. • On conventional MRI and diffusion-weighted imaging (DWI), MPNSTs and BPNSTs showed significant differences in tumor size, margin, presence of perilesional edema, and absence of split fat, fascicular, and target signs. • Absence of a split fat sign and mean apparent diffusion coefficient (ADC) values were robust imaging findings distinguishing MPNSTs from BPNSTs, with a C-index of > 0.9.

Recurrent Schwannomatosis of the Hand

Background: Peripheral nerve sheath tumors (PNSTs) are neoplastic soft tissue masses generated from the abnormal proliferation of Schwann cells. Often, these tumors occur in isolation and are known as schwannomas or neurilemmomas. The presence of multiple schwannomas is known as schwannomatosis. The purpose of this article is 2-fold: (1) to review the relevant literature and describe a unique case of this rare condition; and (2) to emphasize salient clinical considerations in the diagnosis and treatment of schwannomatosis. Methods: In this report, we describe the case of a 52-year-old white man who presented with multiple recurrent soft tissue masses of the right hand. On initial presentation, he described pain across his right hand and index finger, which persisted despite numerous prior operations. The index finger had a flexion contracture around the location of the proximal interphalangeal joint, and there were multiple tender masses along the length of the finger and palm. Results: Segmental excision of the affected radial digital nerve was performed. A pulp flap based on contralateral neurovascular bundle resulted in a sensate, pain-free digit. Tissue pathology confirmed the diagnosis of multiple neurilemmomas. Conclusions: We report the success of a radial digital neurectomy in a patient with widespread neurilemmomas, who had previously excluded that painful digit from use. It was through careful consideration of the preoperative differential diagnosis, by valuing the preoperative imaging, and by considering all surgical options with specific attention paid to skin flap design that this good outcome of a fully sensate, pain-free, mobile index finger was achieved.

Thinking beyond hernia: a review of non-hernia groin lumps

With increasing reliance on imaging, a large number of patients presenting with a groin lump are being referred to radiology to confirm the diagnosis of hernia, usually with an ultrasound in the first instance (occasionally MRI or CT). However, when imaging of the groin was performed, we have encountered many different kinds of non-hernia lesions in our practice. Such lesions can be categorized based on their tissue of origin and pathology. A specific diagnosis can often be reached using ultrasonography, MRI or a combination of imaging modalities. This review article will help general, musculoskeletal and abdominal radiologists to understand the anatomy of the groin, diagnose and characterise soft tissue lesions that may present as a groin lump, provide guidance for further imaging and insight into imaging features which may need specific investigations like core biopsy, tertiary referral and review at multidisciplinary meetings.

Extraprostatic Uptake of 18F-Fluciclovine: Differentiation of Nonprostatic Neoplasms From Metastatic Prostate Cancer

OBJECTIVE. Fluciclovine is a synthetic radiolabeled amino acid analog used for imaging of biochemical recurrent prostate cancer. Uptake of fluciclovine is mediated by several amino acid transporters, including alanine-serine-cysteine transporter 2 and large neutral amino acid transporters, which are known to be overexpressed in other malignancies. CONCLUSION. Knowledge of the common patterns of prostate cancer recurrence, in addition to what other neoplasms can show uptake, is critical for accurate study interpretation.

Secondary Neurolymphomatosis of the Radial Nerve: A Diagnostic Challenge

BACKGROUND Secondary neurolymphomatosis is a rare clinical condition that may be observed in patients with hematologic malignancies. Clinical findings can overlap with other conditions. Diagnosis can be obtained by magnetic resonance imaging (MRI) and imaging with positron emission tomography (PET) and confirmed by biopsy. CASE REPORT A 55-year-old male patient with known previous history of periocular non-Hodgkin's lymphoma mucosa-associated lymphoid tissue (MALT) type presented reporting he had a focal soft-tissue swelling mass on the external side of the right arm, suspected for lipoma. US, MRI, and FDG PET/CT were performed, revealing malignant imaging characteristics of the lesion, suspected to be a neurolymphoma. A biopsy confirmed the nature of the lesion. No further sites of malignancy were detected on whole-body PET/CT. CONCLUSIONS Lymphomatous involvement of peripheral nerves may clinically overlap with other, more common, benign conditions; therefore, although it is rarer, this diagnosis has to be considered in patients with a clinical history of hematologic malignancies.

Nerve root metastasis of gastric adenocarcinoma: A case report and review of the literature

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Metastatic involvement of peripheral nerves by perineural invasion from an adjacent cancer is not uncommon.

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Nerve root metastasis without extension from an adjacent process has been seldom reported in case of solid tumors.

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No cases of gastric adenocarcinoma metastasis to the nerves have been reported to date.

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In case of known malignancy and refractory pain, the possibility of a nerve root metastasis should be considered.

Introduction

Nerve root metastasis without extension from an adjacent process has been seldom reported in case of solid tumors. We describe a case of solitary nerve root metastasis of gastric adenocarcinoma, likely due to hematogenous spread.

Case presentation

A 75-year-old man presented with radiculopathy refractory to medical treatment. MRI and CT demonstrated a right-sided S1 nerve root mass involving the spinal ganglion in its intra-foraminal region with avid enhancement, initial erosive bone changes on sacral foramina and focal hyperaccumulation on 18F – FDG CT-PET, suspicious for metastasis. The histopathological examination confirmed a metastasis of gastric adenocarcinoma.

Discussion

A review of the current literature revealed only ten cases of hematogenous metastases to spinal nerve root ganglia; the primary lesions in those cases were an oat cell carcinoma of the lung, two cases of colonic adenocarcinoma, a case of uterine adenocarcinoma, a ductal breast carcinoma, a Ewing’s sarcoma, a Renal Cell Carcinoma, a gastro-intestinal stromal tumor, a follicular thyroid carcinoma, a pulmonary adenocarcinoma.

Conclusion

In the setting of a known malignancy, a nerve root metastasis should be considered in the differential diagnosis of a nerve root mass, although it occurs very rarely.

Sonographic evaluation of uncommonly assessed upper extremity peripheral nerves: anatomy, technique, and clinical syndromes

Targeted ultrasound of the median, ulnar, and radial nerves is a well-established technique for suspected upper extremity peripheral neuropathy. However, sonographic imaging of the brachial plexus and smaller peripheral nerve branches is more technically difficult and the anatomy is less familiar to many radiologists. As imaging techniques improve, many clinicians refer patients for imaging of previously less-familiar structures. In addition, some patients may present with injuries that could involve local neurovascular structures. Finally, patients presenting with isolated peripheral neuropathies may be referred for perineural injections with local anesthetic for diagnostic purposes, or steroid for therapeutic reasons. This requires sonologists to have a firm understanding of the courses of these nerves and the surrounding anatomic landmarks that can be used to accurately identify and characterize them. We discuss clinical syndromes referable to specific peripheral nerve branches in the upper extremity, the relevant anatomy, and sonographic technique.

Paraspinal Schwannoma of dorsal ramus nerve: A case report

Spinal Schwannomas are benign nerve sheath tumors and the most common intradural extramedullary tumors of the spine, mainly occurring in the cervical and lumbar region. The location distinct from the spinal canal is very rare. We report a rare case of a 45year old male with Schwannoma in the dorsal paraspinal musculature. Complete surgical excision of the lesion was performed with clear margins and neuropathological analysis revealed a Schwannoma. There has been no recurrence after 6 months.