Malignant Peripheral Sheath Tumor Research Articles

Malignant Peripheral Nerve Sheath Tumor, a Heterogeneous, Aggressive Cancer with Diverse Biomarkers and No Targeted Standard of Care: Review of the Literature and Ongoing Investigational Agents.

Malignant peripheral sheath tumor (MPNST) is a rare, aggressive form of soft-tissue sarcoma that presents a unique set of diagnostic and treatment challenges and is associated with major unmet treatment medical needs. The chief aim of this review is to consider the epidemiology, histology, anatomic distribution, pathologic signaling pathways, diagnosis, and management of MPNST, with a focus on potential targeted therapies. A subordinate objective was to establish benchmarks for the antitumor activity of such treatments. MPNST has an incidence of 1:100,000 in the general population and 1:3500 among patients with the inherited condition of neurofibromatosis-1. Spindle-cell sarcomas of neural-crest origin, MPNSTs are frequently situated in the extremities and pelvis/trunk, often at the confluence of large nerve roots and bundles. Highly copy-number aberrant and enriched in chromosome 8, MPNSTs have a complex molecular pathogenesis that likely involves the interplay of multiple signaling pathways, including Ras/AKT/mTOR/MAPK, EGFR, p53, PTEN, and PRC2, as well as factors in the tumor microenvironment. A combination of magnetic resonance imaging (MRI) and positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) enables comprehensive assessment of both morphology and metabolism, while MRI- and ultrasound-guided core needle biopsy can confirm histopathology. Although surgery with wide excisional margins is now the chief curative approach to localized disease, MPNST-specific survival has not improved in decades. For advanced and metastatic MPNST, radiation and chemotherapy (chiefly with anthracyclines plus ifosfamide) have somewhat promising but still largely uncertain treatment roles, chiefly in local control, downstaging, and palliation. No single druggable target has emerged, no objective responses have been observed with a number of targeted therapies (cumulative disease control rate in our review = 22.9-34.8%), and combinatorial approaches directed toward multiple signal transduction mechanisms are hallmarks of ongoing clinical trials. Despite advances in our understanding of the genetics and molecular biology of MPNST, further research is warranted to: (1) unravel the complex pathogenesis of this condition; (2) improve diagnostic yield; (3) delineate the appropriate roles of chemotherapy and radiation; and (4) develop a targeted therapy (or combination of such treatments) that is well tolerated and prolongs survival.

An Unusual Pigmented Plaque in a Newborn.

An Unusual Pigmented Plaque in a Newborn.

Successful Management of Intrathoracic Phrenic Malignant Peripheral Nerve Sheath Tumor by Multimodal Treatment

Malignant peripheral nerve sheath tumors (MPNSTs) are rare and can be associated with type 1 neurofibromatosis. They are rarely located at the mediastinum, most often at the posterior mediastinal compartment or the paravertebral gutters. MPNSTs of the anterior mediastinum arising from the phrenic nerve are exceptional. Their prognosis is poor due to the high potential of local tumor recurrence and metastasis. Complete surgical resection remains the only radical treatment. However, the outcomes after this treatment alone cannot be considered satisfactory. Preoperative chemotherapy could be an interesting therapeutic option for unresectable tumors. We report here the case of a 77-year-old woman with an MPNST located at the anterior mediastinum arising from the phrenic nerve. This tumor was successfully managed with multimodal therapy combining preoperative chemotherapy, complete surgery and adjuvant radiation. J Med Cases. 2020;11(5):120-124 doi: https://doi.org/10.14740/jmc3464

Malignant Peripheral Nerve Sheath Tumor Arising from Neurofibromatosis Type 1: A Case Report and Literature Review

Malignant Peripheral Nerve Sheath Tumor Arising from Neurofibromatosis Type 1: A Case Report and Literature Review

CHD4 as a Potential Biomarker in Differentiating Between Cellular Schwannoma and Malignant Peripheral Nerve Sheath Tumor.

Cellular schwannoma is an uncommon variant of benign peripheral nerve sheath tumors, but is commonly misdiagnosed as malignant peripheral sheath tumor (MPNST). Conventional methods that are used to distinguish cellular schwannoma from MPNST include immunohistochemistry (IHC) staining. However, most markers cannot precisely differentiate these 2 tumor types, and thus identification of a better marker is needed to improve the accuracy of diagnosis. Here, we evaluate the use of chromodomain helicase DNA-binding protein 4 (CHD4) as a specific marker for cellular schwannoma by comparing CHD4 and S-100 IHC staining in 14 cellular schwannoma and 17 MPNST tissue samples. Our results indicated that nuclear CHD4 stains were in moderate-to-high in 94% MPNST (16 cases) and 93% cellular schwannoma (13 cases). However, cytoplasmic CHD4 stains were moderate-to-high in 93% cellular schwannoma (13 cases) but negative-to-weak in 100% MPNST (17 cases). In contrast, the S-100 stains were moderate-to-high in 86% of the cellular schwannoma (12 cases) and in 35% of the MPNST (6 cases). Taken together, the results indicated that different location of CHD4 staining is a potential biomarker to differentiate cellular schwannoma from MPNST.

Loss of Expression of a Novel Chromatin Remodeler SMARCA1 in Soft Tissue Sarcoma.

Introduction:Vital cellular processes such as proliferation and differentiation are regulated by chromatin remodeling complexes. A variety of neoplasms have been discovered to have genomic alterations (GAs) and loss of immunohistochemical (IHC) expression of chromatin remodelers ARID1A (BAF250A), SMARCA2 (BRM), SMARCA4 (BRG1), and SMARCB1 (INI1). SMARCA1 (SNF2L) is another member of the chromatin remodelers, and has not yet been studied in neoplasia. As SMARCA1 is located on chromosome X, could be potentially inactivated by a single hit. We aimed to evaluate GAs and protein expression of SMARCA1 in soft tissue tumors.Method:The publically available cBioPortal.32e34 platform was queried to analyze data on soft tissue tumors from The Cancer Genome Atlas project (TCGA) related to SMARCA1 GAs. Our institutional archives were queried to collect 26 cases of soft tissue tumors including 10 undifferentiated sarcomas, 5 leiomyosarcomas, 6 liposarcomas, and 5 malignant peripheral sheath tumors (MPNST). IHC for SMARCA1 with an SNF 2C4 monoclonal antibody was performed on whole tissue sections.Results:SMARCA1 GAs were present in 8/261 soft tissue sarcomas (3%) in the TCGA dataset. Leiomyosarcomas had most common SMARCA1 GAs in 6/99 cases. SMARCA1 deletions existed in 1/56 dedifferentiated liposarcomas and 1/48 undifferentiated sarcomas. No SMARCA1 GAs occurred in other sarcoma subtypes. SMARCA1 IHC was studied in the sarcoma subtypes with potential SMARCA1 alterations in our institutional cases. SMARCA1 nuclear expression was lost in 3/10 cases (30%) of undifferentiated sarcoma, and 2/5 cases of MPNST (40%). SMARCA1 expression was intact in all cases of leiomyosarcoma and liposarcoma.Conclusion:This is the first study to demonstrate loss of expression of SMARCA1 in soft tissue sarcomas subtypes, including undifferentiated sarcoma. Our study highlights merit for further investigation on the role of SMARCA1 in the differentiation process and molecular mechanisms of SMARCA1 inactivation.

Diagnostic Quality of Magnetic Resonance Imaging Interpretation for Peripheral Nerve Sheath Tumors: Can Malignancy Be Determined?

Background Optimal management of peripheral nerve sheath tumors including neurofibromas, schwannomas, and malignant peripheral sheath tumors (MPNSTs) is predicated on knowing the specific pathology. Magnetic resonance imagining (MRI) has the potential to provide insight in the tumor type, yet imprecision in diagnosis remains. We assessed the accuracy of preoperative imaging diagnoses by comparing them with postoperative histopathologic diagnoses. We specifically focus on erroneous diagnosis of MPNSTs. Methods We reviewed all pathologically confirmed cases of nerve sheath tumors treated at our institution retrospectively from 2007 to 2015. Pre- and postoperative imaging data were reviewed for imaging-based diagnosis and compared with postresection pathologic diagnosis. Results The study included 127 patients: 82 diagnosed with neurofibroma, 17 with schwannoma, 24 with MPNST, and 4 with other histology types. A mean age of 40.8 ± 20.4 years, mean tumor size of 4.3 ± 3.6 cm, and mean follow-up of 29.1 ± 21.6 months were recorded. A family history of neurofibromatosis type 1 (NF1) was seen in 58 patients (46%). A discordant diagnosis from preoperative imaging and postoperative pathology was found in 65 individuals (51%). Most discordant diagnoses (n = 34) were inconclusive interpretation of preoperative imaging; however, 10 patients were diagnosed with a benign or unknown lesion on preoperative imaging but had an MPNST on histopathology. Patients with MPNST were more likely than those with benign pathologies to have larger lesions (7.6 ± 4.8 cm versus 3.5 ± 3.3 cm; p = 0.004); however, a statistically acceptable threshold value could not be found to separate benign from malignant lesions. Clinical factors, such as NF1 status, did not meaningfully improve preoperative diagnosis. Conclusions These results suggest that routine MRI is insufficient to guide surgical decision making reliably. Additional imaging techniques may be necessary to delineate the radiologic features of nerve sheath tumors to determine pathology more precisely.

Prognostic factors of primary resected retroperitoneal soft tissue sarcoma: Analysis from a single asian tertiary center and external validation of gronchi's nomogram.

Surgery is the potentially curative treatment for retroperitoneal sarcoma (RS), but complete resectability is frequently a challenge. This study aimed to characterize the clinical features, prognostic factors and treatment outcomes. A cohort of 144 patients with RS was surveyed retrospectively from January 1st, 2000 to July 30th, 2011. The prognostic influence of clinicopathological characteristics as well as treatments on local recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), and overall survival (OS), were examined by univariate and multivariate analyses. A histology-specific nomogram developed by Gronchi et al was used for validation. Liposarcoma, leiomyosarcoma, and malignant peripheral sheath tumor (MPNST) were the most common histologies (70%). Multivariate analysis revealed FNCLCC tumor grade was the most significant prognostic factor for OS (P = 0.001) and DMFS (P < 0.001) and complete resection was the only significant prognostic factor for LRFS (P = 0.043). Incomplete resection of grade 3 tumor was significantly associated with a worse OS. Despite some differences in characteristics between our patients and Gronchi's cohort, external validation of Gronchi's nomogram demonstrated excellent concordance in predicting survival. Our study demonstrated tumor grade and surgical margins had significant prognostic influence and the Gronchi's nomogram has an excellent applicability in predicting survival of STS patients. J. Surg. Oncol. 2016;113:355-360. © 2016 Wiley Periodicals, Inc.

Indicator Exploration for Cancers in Women with Neurofibromatosis Type 1 - A Multi-Centre Retrospective Study

Objective: Neurofibromatosis type 1 (NF1) is a complex hereditary syndrome with multi-systemic involvement and propensity to develop a variety of tumors. Despite the increased risk for malignant neoplasms and shortened life-span, there is no targeted cancer surveillance strategy. Clinical features of NF1 and family history may be associated with occurrence of certain neoplasms and serve as indicators for targeted surveillance. Methods: This multi-centre retrospective study reviewed the records of 423 women with NF1. The associations between neoplasms, clinical features and family history were analyzed. Results: The occurrence of breast cancers is positively associated (p = 0.004) with family history of any cancers, 9.6% (12/125) with family history vs. 2.7% (8/298) without. An association between NF1 clinical phenotypes (i.e. dermal neurofibroma burden) and cancer was not observed. However, the rate of malignant peripheral sheath tumor (MPNST) was significantly higher (p = 0.049) in women with plexiform neurofibroma (PN) than women without, 7.9% (11/139) vs. 3.14% (7/223). Women with learning disabilities have a higher rate (p = 0.019) of central nervous system (CNS) tumors including optic glioma (OPG) than women without, 22.2% (20/90) vs.11.2% (21/187). European Americans (EAs) are significantly more likely (p = 0.002) to develop CNS tumors (21.2%, 41/193) than African Americans (AAs) (6.8%, 6/88). Conclusion: Family history of any cancers, preexisting PN, learning disability and EA ancestry is linked to higher risk of breast cancer, MPNST, and CNS tumors/OPG, respectively.

CT and MRI features of malignant peripheral nerve sheath tumor of children

Objective To analyze CT and MR features of malignant peripheral nerve sheath tumor (MPNST)of children. Methods Sixteen patients with histologically proven MPNST were retrospectively reviewed.There were 8 male and 8 female, ages from 0.3 to 11.0 years, and median age was 2.5 years. Sixteen cases were performed with CT plain scan, and eight cases with CT enhancement scans, and three with MR examination. The imaging data were analyzed by two highly experienced doctors and obtained agreements after mutual consultation. Results Among 16 cases, 3 cases were located at neck, 5 cases at waist and back,3 cases at abdominal and pelvic, 2 cases at foot, 1 case at left clavicle, 1 case at right mediastinum, 1 case at right orbit. Fifteen cases appeared as solid masses and 1 case showed a diffuse growth. CT plain scan showed 8 cases were solid-appearing masses and 7 cases were cystic-solid mass. Enhanced CT showed enhancement of solid component was moderate to marked and gradually delayed enhanced while cystic component had no any enhancement. One was located on the left side of the neck and appeared as diffuse growth. Two cases of solid mass type appeared as hypo-intensity on T1WI and hyper-intensity on T2WI, and obviously high signal intensity of cystic component on T2WI, and with significantly heterogeneous enhanced.One case with diffuse growth appeared as hypo-intensity on T1WI and slightly hyper-intensity on T2WI, and with significantly enhanced. Sixteen cases appeared as invasive growth, 11 caseswith multiple organic metastases and recurrences, and 4 cases with neurofibromatosis type I and scoliosis. Conclusion CT and MR appearances of MPNST have certain characteristic features, and can demonstrateaggressive performance and multiple organic metastases, which is helpful for definite diagnosis and treatment plan. Key words: Nerve sheath tumor; Child; Tomography, X-ray computed; Magnetic resonance imaging

Epithelioid Malignant Peripheral Nerve Sheath Tumor

Six decades ago, the epithelioid variant of malignant peripheral nerve sheath tumor (EMPNST) was described. This rare variant is different from the

Clinical analysis of 26 central nervous system malignant peripheral nerve sheath tumors

Objective To explore the diagnosis,comprehensive treatment strategies and prognosis for intracranial and intraspinal malignant peripheral nerve sheath tumors (MPNST).Methods The investigators summarized 26 cases with MPNST which were performed by post-operation pathology from 2004 to 2011.By Log-rank and Cox model analysis,we analyzed the clinical features,radiological manifestations,pathological features,comprehensive treatment strategies and prognosis,and relevant literatures.Results Among the 26 cases,16 cases were male,10 cases were female,17 tumors were in cranial,9 were located in intraspinal.symptoms mainly included pain and impaired dysfunction of nerves.The follow-up data of 21 patients were collected from 1.5 to 102.0 months after surgery.Among these patients,5 patients had died due to tumor recurrence,7 patients were alive with tumor recurrence and 9 patients had no recurrence.Univariate analysis revealed that female gender,gross total resection,and primary MPNST were significantly associated with favorable prognosis(P ＜0.05).Multivariate analysis revealed only gross total resection to be an independent favorable prognostic factor (P =0.006).Conclusions Intracranial and intraspinal MPNST is a kind of rare neoplasm.The recurrence rate and mortality is higher.Gross total resection whenever possible is necessary for prolonged survivals.For patients with incomplete tumor resection,postoperative radiation therapy is recommended. Key words: Malignant peripheral nerve sheath tumors; Central nervous system; Diagnosis; Comprehensive treatment; Prognosis

Spinal intradural malignant peripheral nerve sheath tumor in a child with neurofibromatosis type 2: the first reported case and literature review.

Spinal intradural malignant peripheral nerve sheath tumors (MPNSTs) in children are extremely rare, with only five reported cases in the literature. A 9-year-old female with neurofibromatosis type 2 (NF-2) presented with right hip pain and severe weakness of bilateral legs for 3 months. Magnetic resonance (MR) imaging revealed multiple intradural masses at the T11-L2, L4, and L5-S5 level respectively, and bilateral vestibular schwannomas in the cerebellopontine angle. Partial tumor excision with T11-L2 laminectomy was undertaken and the tumors in the spinal cord were consistent with the diagnosis of epithelioid MPNSTs. No adjuvant therapy was performed after surgery. No metastasis of the tumor was found in the 6-month follow-up MR imaging. She died of brain metastasis at 9 months after surgery. MPNSTs should be added to the differential diagnosis of intradural tumors of the pediatric spine, even in children with NF-2. Multidisciplinary treatment consisting of total surgical removal and adjuvant radiotherapy should be considered due to poor prognosis of this abnormality. To our knowledge, this is the first case of spinal MPNSTs in a child with NF-2 to be published in English literature.

Clinical analysis on 15 cases of malignant peripheral nerve sheath tumor

[Objective]To explore and analyze the biological characteristics and clinical effect of malignant peripheral nerve sheath tumor.[Methods]15 patients with head and neck malignant peripheral nerve sheath tumor in our department were chosen as observation group.15 patients with head and neck benign neurofibroma were.selected aa control group.Observation group underwent palliative operation+ chemotherapy or radiation treatment while control group underwent corresponding operations.The histopathology,early clinical symptom and survival rate were compared in two groups.[Results]①In observation group,the histopathology such as diffuse growth (14 cases,93.33％),average tumor size (3.6± 0.8cm × 2.0 ± 0.5) and remote hemorrhage (10 cases,66.57％) were higher than those in control group,with statistical significant differences (P＜ 0.05),the observation group was worse than control group.②The early clinical symptoms such as acute pain,dyskinesia and dysesthesia in two groups had statistical significant differences (P＜ 0.05),the observation group was much worse than control group.③There were 6 patients having acoustic neurinoma,4 patients had meningioma and 2 patients had gliocytoma in observation group,and the 1 year survival rate was 73.33/ and 5 year survival rate was 6.67％.While the 1 year survival rate and 5 year survival rate were 100％ and 97.56％ respectively in control group.The differences between two groups was obvious and had statistical significance (P ＜ 0.05).[Conclusion]The malignant peripheral nerve sheath tumor has early obvious clinical symptoms,complicated states of illness,poor prognosis,so enough attention should be paid to its clinical diagnosis. Key words: Malignant peripheral nerve sheath tumor; Neurofibroma; Clinical analysis

Expression of nestin and Ki-67 in malignant peripheral nerve sheath tumors and its significance

Objective To explore the expression of nestin and Ki-67 in malignant peripheral nerve sheath tumors (MPNST) and its significance in the differential diagnosis. Methods Immunohistochemical technique (SP) was used to detect the expression of nestin and Ki-67 in 42 cases of MPNST and 24 cases of benign peripheral nerve tumor.Results Total expression of nestin was found in 95.2 ％(40/42) of MPNST.Strong expression of nestin was detected more frequent in MPNST compared to benign peripheral nerve tumors [40.5 ％(17/42) versus 4.2 ％(1/24),x2 =8.403,P =0.004].Ki-67 labeling index in MPNST varied from 1％-70 ％.However,greater than 3 ％ labeling index of Ki-67 staining was observed in 64.3 ％(27 / 42) of MPNST while none of the 24 benign tumors had nuclear staining exceeding 3 ％. The higher Ki-67 labeling index showed significant differences between the two groups (x2 =23.518,P =0.000).Conclusion Nestin and Ki-67 are useful markers in distinguishing MPNST from benign tumors. Key words: Malignant peripheral nerve sheath tumor; Nestin; Ki-67; Immunohistochemistry

Clinicopathological features of lymph node metastatic EMPNST: a case report and review of literatures

Background Mesenchymal malignancies prefer hematogenous spread, while epithelial malignancies tend to prefer lymphatic spread. However, mesenchymal malignancies occasionally generate lymphatic metastases. Objective To investigate the clinicopathological features of the epithelioid malignant peripheral nerve sheath tumor (EMPNST). Methods The clinical data, histopathological, histochemical and immunohistochemical features in one case of EMPNST with lymph node metastases were retrospectively analyzed, and the related literatures were reviewed. Results A 42 ⁃ year ⁃ old woman presented right upper arm and shoulder numbness with a right axillary nodule measuring 4 cm × 4 cm × 3 cm for 2 months. Type⁃B ultrasonic examination showed substantive lesions in right axillary which appeared to be a neurofibroma. CT scan showed soft tissue masses in right axillary with multiple enlarged lymph nodes were considered to be malignant lesions. MR image showed nodules in right armpit muscles were considered to be malignant tumor. The multiple nodules were identified in right axillary and the largest one was about 5 cm × 3 cm × 3 cm intraoperatively. The section of specimen was hard, gray⁃red and sallow in color with focal necrosis. The nodules were partly circumvoluted with blood vessel and without distinct border. The surrounding nerves were not obviously compressed. Microscopically, the structure of lymph node was damaged. The tumor invaded the surrounding fibrous connective tissue and adipose tissue with focal hemorrhage and necrosis. Tumor cells arranged in sheets, nests, and were separated by thin fibrous and blood vessels tissue. Most tumor cells were epithelioid. They were large in size with abundant cytoplasm. Cell border was indistinct, and the cytoplasm consisted of fine granules. Nuclei were invariably intensely hyperchromatic with coarse chromatin, and were vacuolated with prominent nucleoli in the center of the nuclei. Tumor cells showed frequent mitotic activity. Multinucleated giant cells and interstitial mucous degeneration were presented. Immunohistochemical staining showed that tumor cells were positive for S⁃100 protein, strong nuclear reactivity for Sox⁃10, and were positive for vimentin and Col⁃Ⅳ, and were negative for CK, CEA, EMA, Melan⁃A, CD56, CD3 and CD20. P53 positive revealed by 40% nuclear of tumor cells. Ki⁃67 labeling index was above 90%. Histochemical staining showed that the tumor cells were surrounded by reticular fibers. The patient had a medical history which recorded a tumor at the right wrist was removed in other hospital 8 years ago, and the wrist tumor recurred 5 years ago. The pathological diagnosis of the recurred wrist tumor was EMPNST with focal hemorrhage and necrosis. According to the history and the final pathological diagnosis, axillary tumor was diagnosed as lymph node metastasis of EMPNST in right axillary. Conclusion The metastasis of MPNST is mostly through the blood channel. This is the first case of the lymph node metastasis of EMPNST. In clinical work, it should be differentiated from other tumors with similar histopathology. DOI：10.3969/j.issn.1672⁃6731.2012.02.017

Giant malignant peripheral nerve sheath tumors of the occipital scalp

Background: Malignant peripheral nerve sheath tumors (MPNST) are rare neoplasms, usually arising from peripheral nerves or showing a nerve sheath differentiation. Primary MPNSTs of the scalp is exceptionally rare, and only sporadic cases have been reported recently. Objectives: Report a rare case of giant malignant peripheral nerve sheath tumor (MPNST) beneath occipital scalp, and discuss how to treat with this kind of tumor. Methods: Descriptive study of a rare case of giant peripheral nerve sheath tumors of occipital scalp without adjuvant treatment with nine months follow up. Results: In a 52-year-old man with MPNSTs beneath occipital scalp, the tumor was treated with complete surgical resection. Histological examination proved that the lesion was a scalp MPNST. The patient was followed up asymptomatic for the following nine months after surgical resection without adjuvant radiotherapy. Conclusion: MPNSTs beneath the occipital scalp should be treated individually, for those well-circumscribed MPNSTs without bone destruction or brain invasion (low-grade tumors), complete surgical resection with clear margins (if possible) is recommended. Otherwise, adjuvant postoperative radiotherapy is necessary.

Omental vascular pedicle sign: Multidetector CT finding useful for diagnosis of an omental mass

To describe multidetector CT findings of "omental vascular pedicle" sign. "Omental vascular pedicle" sign was defined as dilated omental vein associated with a mass located in omentum and was observed in 7 patients (5 women, 2 men). Mean age was 45 years. CT examinations and patient records were retrospectively reviewed. CT images were obtained by 16-MDCT (n = 1) and 64-dual source MDCT (n = 6). Curved planar and volume rendered images were reconstructed from axial images. Diameter of omental vein and drainage site were recorded. Images were evaluated by 2 radiologists in consensus. Pathologic diagnosis of patients with "omental vascular pedicle sign" was omental angiosarcoma (n = 1), endometrial adenocarcinoma (n = 2), ovarian serous adenocarcinoma (n = 2), mixed gonadal tumor (n = 1), malignant peripheral sheath tumor (n = 1). In 5 patients, omental vein drained into splenic vein and in 2 patients it drained into right gastroepiploic vein. Mean size of omental masses associated with omental vascular pedicle was 7.1 × 4.5 cm (range 15 × 11 cm to 2.7 × 1.6 cm). Mean diameter of omental vein was 3.1mm (range 6-1.5mm). Diameter of the omental vein increased with the increasing size of omental masses and Pearson's correlation coefficient was 0.99. "Omental vascular pedicle sign" can be helpful to objectively diagnose omental masses in patients with primary and metastatic omental tumors.

Multicentric Malignant Peripheral Nerve Sheath Tumors of Small Intestine and Thigh: Report of a Case

Primary malignant peripheral nerve sheath tumor (MPNST) of the small bowel is an extremely rare disease. We report a multicentric MPNSTs of the left thigh and jejunum in a 59-year-old male, who visited our hospital twice in seven months because of a subcutaneous lump on the posterior aspect of the left thigh and life-threatening melena respectively. Laparotomy was performed for the small bowel tumor and a segment of the jejunum containing the tumor near its midportion was resected with end-to-end jejunojejunostomy. Histologically, the tumor which had been excised seven months previously was diagnosed as classical MPNST occurring in the left thigh, and that resected this time, as epithelioid MPNST occurring in the jejunum. Distant metastasis to multiple organs occurred one month after resection of the jejunal MPNST, and the patient died three months later. This is the first case of an MPNST arising in the small intestine reported in Taiwan.

Aspects histopathologiques des principales tumeurs des nerfs périphériques

Benign tumors of the peripheral nerves come from ectodermic tissues. This chapter describes the most common forms: the schwannomas and the neurofibromas. Schwannomas have two possible patterns of cells: Antoni A and B types. Neurofibromas are most often associated with neurofibromatosis NF1 and may be localized, diffuse, or plexiform. The benign tumor structures account for the fact that they can be removed with or without preserving the concerned nerve. Malignant tumors (malignant peripheral sheath tumors) come from degeneration of neurofibromas in two out of three cases and have a poor prognosis.