Peripheral neural sheath tumors (PNST)--what a radiologist should know

Peripheral Nerve Sheath Tumor: A Diagnostic and Therapeutic Challenge

INTRODUCTION

Peripheral nerve tumors are a group of rare soft tissue tumors of neuro-ectodermal origin. Although the majority of them are benign in nature, up to 10% can be malignant. The symptoms depend on the site, size, and structures compressed by the tumor.

AIM

To highlight the heterogeneity of signs and symptoms and their presentations, which has often made it difficult for the attending physician to accurately diagnose and direct the patient toward appropriate treatment.

METHODS

Eight patients treated at our tertiary care hospital between 2015 and 2022 were included in this study. They were evaluated in detail. Treatment was surgical. The patients underwent complete excision of the tumor under magnification to help preserve the adjacent neurovascular bundle. All patients were followed up post-operatively to document the status of their symptoms.

RESULTS

The average duration prior to referral to our hospital was 13 months. Seven subjects had pain at presentation, one had neurological deficit. Seven also complained of swelling. Five of the eight lesions were schwannoma, two neurofibroma and one showed malignant histology. Post-operatively, Hoffman Tinel signs improved in all six subjects. five of the seven subjects were completely pain-free, and the other two had a reduction in symptoms.

CONCLUSIONS

Early diagnosis and referral to a specialist center are needed to achieve satisfactory outcomes while treating peripheral nerve tumors. Proliferative lesions should be treated surgically in specialist centers by experienced doctors with appropriate skills and equipment for microsurgical procedures to ensure full recovery.

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.

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.

Large solitary encapsulated neurofibroma of upper arm: A case report

Introduction: Neurofibromas are benign tumors of neuronal origin, occurring most commonly in young adults, with no gender predilection. The connection of neurofibroma with disorders on a general level as von Recklinghausen's disease makes its diagnosis critical. Case report: A 32-old female patient was administered to the Clinic of Plastic surgery, Clinical Center of Montenegro in Podgorica, with a 10-year history of painless, subcutaneous tumor of the right upper arm that grew in size over the last ten years. The patient reported progressive pain and tingling in her right forearm and right hand for the last 12 months. An MRI showed a non-homogenous tumor of the middle third portion of the triceps muscle, in close contact with the humerus but without infiltrating it. The tumor was removed, with a definitive histopathological result of a solitary benign neurofibroma. Conclusions: This example of successful treatment of solitary neurofibroma may serve to increase the awareness of surgeons and radiologists in small countries regarding benign peripheral nerve sheath tumors. The patient is under observation for two years with no signs of relapse and no other features indicative of neurofibromatosis type 1.

Giant Neurofibroma of the Left Median Nerve Associated With Damage of the Ipsilateral Distal Radius

A 74-year-old Caucasian woman presented with a large mass on her left distal radius, which had previously caused a fracture of the bone at this site and the palmar site that was treated with external fixation a year ago. The patient did not mention tumor-related family history and other neoplasms before the fracture of the distal radius. She noticed that the gradually growing mass had appeared after the fracture treatment. A thorough evaluation of the lesion confirmed the diagnosis of a large benign neurofibroma with distal radius impairment. The diagnostic and therapeutic procedure included the complete excision of the tumor and a six-week cast immobilization of the radius. On the final follow-up two years postoperatively, her clinical situation was satisfactory with no signs of recurrence. Although rare, isolated benign neurofibromas of enormous sizes are associated with bone damage. In our view, immediate surgical excision is crucial and enables total recovery postoperatively.

Diagnostic Accuracy of MRI for the Detection of Malignant Peripheral Nerve Sheath Tumors: A Systematic Review and Meta-Analysis

OBJECTIVE. This systematic review and meta-analysis evaluates the diagnostic accuracy of MRI for differentiating malignant (MPNSTs) from benign peripheral nerve sheath tumors (BPNSTs). MATERIALS AND METHODS. A systematic review of MEDLINE, Embase, Scopus, the Cochrane Library, and the gray literature from inception to December 2019 was performed. Original articles that involved at least 10 patients and that evaluated the accuracy of MRI for detecting MPNSTs were included. Two reviewers independently extracted clinical and radiologic data from included articles to calculate sensitivity, specificity, PPV, NPV, and accuracy. A meta-analysis was performed using a bivariate mixed-effects regression model. Risk of bias was evaluated using QUADAS-2. RESULTS. Fifteen studies involving 798 lesions (252 MPNSTs and 546 BPNSTs) were included in the analysis. Pooled and weighted sensitivity, specificity, and AUC values for MRI in detecting MPNSTs were 68% (95% CI, 52-80%), 93% (95% CI, 85-97%), and 0.89 (95% CI, 0.86-0.92) when using feature combination and 88% (95% CI, 74-95%), 94% (95% CI, 89-96%), and 0.97 (95% CI, 0.95-0.98) using diffusion restriction with or without feature combination. Subgroup analysis, such as patients with neurofibromatosis type 1 (NF1) versus those without NF1, could not be performed because of insufficient data. Risk of bias was predominantly high or unclear for patient selection, mixed for index test, low for reference standard, and unclear for flow and timing. CONCLUSION. Combining features such as diffusion restriction optimizes the diagnostic accuracy of MRI for detecting MPNSTs. However, limitations in the literature, including variability and risk of bias, necessitate additional methodologically rigorous studies to allow subgroup analysis and further evaluate the combination of clinical and MRI features for MPNST diagnosis.

Mechanisms, Treatment, and Patient Outcome of Iatrogenic Injury to the Brachial Plexus-A Retrospective Single-Center Study

BACKGROUND

Injury to the brachial plexus is a devastating condition, with severe impairment of upper extremity function resulting in distinct disability. There are no systematic reports on epidemiology, causative mechanisms, treatment strategies. or outcomes of iatrogenic brachial plexus injury (iBPI).

METHODS

We screened all cases of iatrogenic nerve injuries recorded between 2007 and 2017 at a single specialized institution. Mechanism of iBPI, type of previous causative intervention, location and type of the lesion as well as the type of revision surgery and functional patient outcome were analyzed.

RESULTS

We identified 14 cases of iBPI, which all presented with significant impairment of upper extremity motor function (at least 1 muscle Medical Research Council grade 0). Neuropathic pain was present in most patients (11/14). Orthopedic shoulder procedures such as rotator cuff fixation, arthroplasty, and repositioning of a clavicle fracture accounted for iBPI in 7 of 14 patients. Other reasons for iBPI were resection or biopsy of a peripheral nerve sheath tumor in 3 patients or lymph node situated at the cervicomediastinal area in 2 patients. Mechanisms also included transaxillary rib resection in one and sternotomy in another patient. The treatment of iBPI was conducted according to each individual's needs and included neurolysis in 4, nerve grafting in 9, and nerve transfers in 1 patient. We found improved symptoms after treatment in most patients (11/14).

CONCLUSIONS

Most common causes for iBPI were shoulder surgery and resection or biopsy of peripheral nerve sheath tumor and lymph nodes. Early referral to specialized peripheral nerve centers may help to improve functional patient outcome.

Benign Peripheral Nerve Sheath Tumor in a Distance Runner

A 31-year-old female runner presented to physical therapy via direct access with an 8-month history of atraumatic left lateral calf pain. Following 1 month of physical therapy, the patient was referred to an orthopaedic sports medicine physician. Ultrasound imaging revealed a 2-cm hypoechoic mass with well-defined margins in the left proximal lateral soleus, while Doppler ultrasound demonstrated increased color flow surrounding the mass. Magnetic resonance imaging findings were consistent with a nerve sheath tumor, and ultrasound-guided tissue biopsy determined the mass to be a benign peripheral nerve sheath tumor. J Orthop Sports Phys Ther 2017;47(2):125. doi:10.2519/jospt.2017.6780.

Massive exophytic malignant peripheral nerve sheath tumor

We present a case of a solitary neurofibroma involving the right posterior shoulder of a 69-year-old man with degeneration into a massive, malignant peripheral nerve sheath tumor measuring more than 3 times the average reported size. The radiographic, magnetic resonance imaging, and computed tomographic features are compared with the gross appearance and pathology.

Benign nerve tumours of the hand (excluding wrist)

INTRODUCTION

Hand tumours of neural origin are rare in clinical practice. The aim of this work is to present our experience in operative treatment of benign nerve tumours located in the hand. Special emphasis has been put on determining the occurrence rates of particular tumour types characterized by their unique histopathological patterns and describing detailed location of the lesions. The obtained results of treatment were assessed.

MATERIALS AND METHODS

The study comprised of 26 patients, both female (19) and male (7). The mean age and age range of the female and male patients were 44.8 years (range, 21-73 years) and 39.6 years (range, 21-74 years), respectively. The patients underwent operative treatment for tumours of neurogenic origin located in the hand between the years 1990 and 2013. In total, 31 tumours in 26 patients were removed. The most common site of tumour origin was small cutaneous branches and only exceptionally the tumours arose from common digital nerves (2 patients). No patient was lost to postoperative follow-up. The shortest period of postoperative follow-up covered 1 year.

RESULTS

No tumour recurrence was detected during postoperative follow-up examinations. The patients reported neither pain nor presence of paraesthesias. Neurofibromas (17 tumours) predominated in the gathered clinical material, while the second most common group of tumours were schwannomas (12 tumours).

CONCLUSIONS

(1) Benign nerve tumours of the hand are rare. Neurofibromas and schwannomas predominate among them. Tumours having other histopathological patterns are extremely uncommon. (2) The prognosis after resection of benign nerve tumours located in the hand is good and the risk of postoperative complications and recurrence is low.

Parapelvic solitary neurofibroma of the kidney

A middle-aged man presented with intermittent gross haematuria and dull aching left flank pain for 1 month. He was a chronic smoker for 15 years. Contrast-enhanced CT scan of the abdomen detected a 4.5×3.0×2.5 cm, heterogeneous and poorly contrast-enhancing mass in the left renal sinus and upper ureteric region causing narrowing of the pelviureteric junction and upper ureter. Considering it to be a transitional cell carcinoma of upper urinary tract, the patient underwent laparoscopic radical nephroureterectomy. Histopathology revealed the mass to be a neurofibroma in the renal sinus extending around the upper ureter.

Solitary preperitoneal neurofibroma: a case report

BACKGROUND

Neurofibroma is a rare benign tumor. The isolated presence of such lesions in the preperitoneal space with no evidence of systemic disease has never been reported in the literature.

CASE PRESENTATION

A 29-year-old white man presented with a 12 months history of progressive abdominal distension. Clinical examination revealed a bulky hypogastric mass. Abdominal computed tomography and pelvic magnetic resonance imaging showed a large, well defined preperitoneal tumor measuring 18 x 17 cm extending in the pelvis. A computed tomography guided biopsy was performed which revealed a neurofibroma. Exploratory laparotomy showed a well encapsulated elastic soft tumor in the preperitoneal space which measured 17 x 18 cm and weighted 2 Kg. The tumor was completely excised. No recurrence occurred after one year of follow-up.

CONCLUSION

Solitary preperitoneal neurofibroma is an extremely rare benign tumor. Its clinical and radiological signs are nonspecific. Preoperative histology can be useful to guide the surgical approach which is the only curative treatment.

Results of surgical treatment of schwannomas arising from extremities

Schwannomas are benign neoplasms derived from Schwann cells. In this work, we present our experience in operative management of schwannomas and analyse results of treatment. Clinical material consisted of 34 patients, in whom 44 schwannomas located in extremities were excised between 1985 and 2013. Thirty-five tumours originated from major peripheral nerves and 9 from small nerve branches. Postoperatively, in the first group of tumours, pain resolved in 100%, paresthesias in 83.3%, and Hoffmann-Tinel sign in 91.6% of the patients. Improvement in motor function was noted in 28.5% of the cases, in sensory function: complete in 70%, and partial in 15%. The most frequently affected major peripheral nerves were the ulnar (11 tumours) and median (5 tumours) nerves. Schwannomas originating from small nerve branches were removed without identification of the site of origin. After their resection, definitive healing was achieved. Conclusions. (1) Schwannomas located in extremities arise predominantly from major peripheral nerves, most commonly the ulnar and median nerves. (2) Gradual tumour growth causes exacerbation of compression neuropathy, creating an indication for surgery. (3) In most cases, improvement in peripheral nerve function after excision of schwannoma is achieved. (4) The risk of new permanent postoperative neurological deficits is low.

Results of surgical treatment of schwannomas arising from extremities

Schwannomas are benign neoplasms derived from Schwann cells. In this work, we present our experience in operative management of schwannomas and analyse results of treatment. Clinical material consisted of 34 patients, in whom 44 schwannomas located in extremities were excised between 1985 and 2013. Thirty-five tumours originated from major peripheral nerves and 9 from small nerve branches. Postoperatively, in the first group of tumours, pain resolved in 100%, paresthesias in 83.3%, and Hoffmann-Tinel sign in 91.6% of the patients. Improvement in motor function was noted in 28.5% of the cases, in sensory function: complete in 70%, and partial in 15%. The most frequently affected major peripheral nerves were the ulnar (11 tumours) and median (5 tumours) nerves. Schwannomas originating from small nerve branches were removed without identification of the site of origin. After their resection, definitive healing was achieved. Conclusions. (1) Schwannomas located in extremities arise predominantly from major peripheral nerves, most commonly the ulnar and median nerves. (2) Gradual tumour growth causes exacerbation of compression neuropathy, creating an indication for surgery. (3) In most cases, improvement in peripheral nerve function after excision of schwannoma is achieved. (4) The risk of new permanent postoperative neurological deficits is low.

Retroperitoneal pararenal isolated neurofibroma: report of a case and review of literature

The neurofibroma is a tumour of neural origin. This kind of neoplasm, though, is generally skin located. Rare cases in deep organs or in the peritoneal cavity are also reported in the literature. There are two types of neurofibromas, localized and diffuse; the latter is associated with von Recklinghausen disease and always occurs together with skin neurofibromas. Here we report the case of a 47-year-old man affected by retroperitoneal neurofibroma, but not associated with von Recklinghausen disease. A computed tomography (CT) scan described a retroperitoneal pararenal lesion with no clear involvement of adjacent viscera. We describe the diagnostic modality, treatment planning and the timing of treatment of this neoplasm, reviewing also the literature.