Malignant peripheral nerve sheath tumors

Concurrence of malignant peripheral nerve sheath tumor at the site of complex regional pain syndrome type 1 - a case report -

Malignant peripheral nerve sheath tumors (MPNSTs) are very rare sarcomas derived from various cells in the peripheral nerve sheath. Malignant peripheral nerve sheath tumors have a known association with neurofibromatosis type 1. Diagnosis of MPNSTs is difficult in patients with chronic pain, when MPNST occurs at an overlapping area of chronic pain. Therefore, the diagnosis can be missed unless clinicians pay attention to the possibility of this disease. Here in, we report a case of concurrent malignant peripheral nerve sheath tumor with complex regional pain syndrome type 1. A 44-year female patient, who was diagnosed with complex regional pain syndrome (CRPS) type 1 in her left ankle, visited our clinic because of aggravated pain. The cause of the aggravated pain was revealed as concurrent MPNST in the left common peroneal nerve territory, which overlapped the site of pain from CRPS.

Identification of serum microRNAs in genome-wide serum microRNA expression profiles as novel noninvasive biomarkers for malignant peripheral nerve sheath tumor diagnosis

Recent studies found that serum microRNAs (miRNAs) could serve as stable and noninvasive biomarkers for disease diagnosis. We used genome-wide serum miRNA expression analysis to investigate the role of serum miRNAs in distinguishing malignant peripheral nerve sheath tumor (MPNST) patients with and without neurofibromatosis type 1 (NF1) from NF1 patients. A total of 100 patients with NF1, 93 sporadic MPNST patients, and 71 NF1 MPNST patients were enrolled in this two-stage, case-control study. Solexa sequencing was used to screen for miRNAs that expressed differentially in three pooled serum samples from 10 NF1 patients, 10 sporadic MPNST patients, and 10 NF1 MPNST patients. The detected serum miRNAs then were validated in 90 patients with NF1, 83 patients with sporadic MPNST, and 61 NF1 MPNST patients by individual quantitative reverse transcriptase polymerase chain reaction assays. Eight serum miRNAs altered more than fivefold by Solexa sequencing between MPNST patients (with and without NF1) and NF1 patients. MiR-801 and miR-214 increased both in sporadic MPNST patients and NF1 MPNST patients when compared with NF1 patients. The sensitivity and the specificity of sporadic MPNST detection by the two-miRNA signature were 0.747 and 0.856, respectively. MiR-24 was only significantly up-regulated in NF1 MPNST patients. The combination of the three miRNAs (MiR-801, miR-214, and miR-24) could distinguish NF1 MPNST patients from NF1 patients with a sensitivity of 0.820 and a specificity of 0.844. The serum-based miRNA expression profiles could serve as novel noninvasive biomarkers in sporadic MPNST and NF1 MPNST detection.

Excellent response of malignant peripheral nerve sheath tumour of retroperitoneum to radiation therapy

Malignant peripheral nerve sheath tumours are high-grade sarcomas originating from Schwann cells or nerve sheath cells. Most of these tumours are associated with major nerves of the body wall and extremities. The lower extremity and the retroperitoneum are the most common sites. Surgery is the cornerstone of treatment, however, radiation therapy is usually used as an adjuvant treatment. In this paper we present a 57-year-old Iranian woman with malignant peripheral nerve sheath tumour of retroperitoneum who was operated subtotally and then underwent radiation therapy which led to disappearance of all gross residual disease.

Survival meta-analyses for >1800 malignant peripheral nerve sheath tumor patients with and without neurofibromatosis type 1

There are conflicting reports as to whether malignant peripheral nerve sheath tumor (MPNST) patients with neurofibromatosis type 1 (NF1) have worse prognosis than non-NF1 MPNST patients. Large clinical studies to address this problem are lacking due to the rareness of MPNST. We have performed meta-analyses testing the effect of NF1 status on MPNST survival based on publications from the last 50 years, including only nonoverlapping patients reported from each institution. In addition, we analyzed survival characteristics for 179 MPNST patients from 3 European sarcoma centers. The meta-analyses including data from a total of 48 studies and >1800 patients revealed a significantly higher odds ratio for overall survival (OR(OS)) and disease-specific survival (OR(DSS)) in the non-NF1 group (OR(OS) = 1.75, 95% confidence interval [CI] = 1.28-2.39, and OR(DSS) = 1.68, 95% CI = 1.18-2.40). However, in studies published in the last decade, survival in the 2 patient groups has been converging, as especially the NF1 group has shown improved prognosis. For our own MPNST patients, NF1 status had no effect on overall or disease-specific survival. The compiled literature from 1963 to the present indicates a significantly worse outcome of MPNST in patients with NF1 syndrome compared with non-NF1 patients. However, survival for the NF1 patients has improved in the last decade, and the survival difference is diminishing. These observations support the hypothesis that MPNSTs arising in NF1 and non-NF1 patients are not different per se. Consequently, we suggest that the choice of treatment for MPNST should be independent of NF1 status.

A-Z of malignant peripheral nerve sheath tumors

This article reviews the typical and atypical locations, imaging findings, local recurrence, and metastatic pattern of malignant peripheral nerve sheath tumors (MPNSTs). MPNSTs are rare soft tissue sarcomas, commonly occur in extremities, and are often associated with neurofibromatosis. Distinction between benign and malignant tumors can be challenging on imaging. MPNSTs have a poor prognosis; however, rhabdomyoblastic differentiation (malignant triton tumor), which has imaging features similar to MPNSTs, is associated with even more aggressive behavior.

Role of resection of malignant peripheral nerve sheath tumors in patients with neurofibromatosis type 1

OBJECT

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive sarcomas that often arise from major peripheral nerves. Approximately half of MPNSTs arise in patients with neurofibromatosis Type 1 (NF1) who, in comparison with patients without NF1, present at younger ages and with larger tumors that are commonly associated with extensive plexiform neurofibromas. These tumors therefore pose a particularly difficult treatment challenge because of the morbidity often associated with attempted gross-total resection (GTR). Here, the authors aim to examine what role the extent of resection and other covariates play in the long-term survival of patients with NF1 in the setting of MPNST.

METHODS

The authors retrospectively reviewed the records of 23 adult patients with NF1 who underwent surgery for MPNSTs at their institution between 1991 and 2008. The primary end points of the study were mortality, local recurrence, and metastasis. Kaplan-Meier survival curves were evaluated for all patients. Differences for each of the primary end points were evaluated based on cause-specific covariates, which included tiered tumor size, tumor location, grade, resection margin status, postoperative weakness, and use of chemotherapy and radiation therapy. Multivariate analysis was performed using Cox proportional hazards models.

RESULTS

Gross-total resection (p = 0.01) and surgical margin status (p = 0.034) had a statistically important role in prolonging overall survival in patients with NF1 by univariate analysis. When tumor size, location, grade, postoperative weakness, and radiation therapy were also taken into account using multivariate analysis, GTR continued to be a significant prognostic factor (p = 0.035).

CONCLUSIONS

These findings suggest that GTR offers significant long-term benefit on survival in patients with NF1. Benefit on survival occurred independently of all other covariates, suggesting that complete resection should be the principal goal of treatment in this patient population.

A huge malignant peripheral nerve sheath tumor with hepatic metastasis arising from retroperitoneal ganglioneuroma

Ganglioneuromas (GNs) are the rarest and most benign of the neuroblastic tumors. We experienced a case of huge retroperitoneal GN which differentiated into malignant peripheral nerve sheath tumors (MPNST) with hepatic metastasis. The tumor was located in the upper right quarter of the abdomen and pressed the right lobe of the liver, which was initially misdiagnosed as a liver carcinoma. The tumor shared blood supply with the right liver lob and had rich blood supplies from the abdominal aorta, renal artery and hepatic artery. It was also associated with skin pigment and recurrence shortly following resection. Our finding demonstrated that MPNST is a potent invasive malignant tumor and metastasis earlier with very poor prognosis.

Favorable outcome after radical resection and subsequent local irradiation of malignant peripheral nerve sheath tumor in the cervical spine

A 25-year-old man presented with malignant transformation to malignant peripheral nerve sheath tumor (MPNST) in the cervical spine associated with neurofibromatosis type 1. He presented with a 3-week history of rapidly increasing weakness and numbness in all four extremities. Magnetic resonance (MR) imaging of the cervical spine demonstrated a dumbbell-shaped tumor, which compressed the spinal cord at the C2-3 level. The tumor was excised, mainly within the spinal canal to decompress the spinal cord. The histological diagnosis was benign neurofibroma. Three months after surgery, he rapidly developed progressive tetraparesis and MR imaging revealed marked regrowth of an extradural mass into the spinal canal. At reoperation, the regrown mass in the spinal canal was totally excised. The histological diagnosis revealed MPNST. He underwent radiation therapy, with a total dose of 32 Gy, for approximately 3 weeks after the second surgery, but MR imaging showed tumor regrowth within the spinal canal, and his condition deteriorated. The decision was made to remove the tumor radically, including the involved facet and extradural lesion. Posterior fusion using a pedicle screw was performed one month later. He manifested no additional neurological deficits. He has been free of relapse for 46 months. Radical resection remains the most effective treatment for MPNST, although complete removal with a clear tumor margin is often impossible in practice.

Malignant peripheral nerve sheath tumor: the utility of fascicular biopsy and teased fiber studies

We present the case of a 67-year-old man with a malignant peripheral nerve sheath tumor (MPNST) affecting the brachial plexus. He presented with progressive right upper extremity paresthesias, numbness, weakness, and severe pain. Nerve conduction studies/electromyography demonstrated a right lower and middle trunk predominant brachial plexopathy. Three-tesla magnetic resonance imaging of the brachial plexus showed a soft tissue mass with central necrosis and cystic changes and irregular contrast enhancement. Positron emission tomography showed increased fluorodeoxyglucose uptake within the mass. Targeted fascicular nerve biopsy revealed hypercellular tumor, featuring atypical cells with mitotic figures and limited immunoreactivity for S-100 protein. The findings were those of an MPNST. The effects on the variably involved fascicles were also seen in teased fiber preparations, paraffin sections, and through immunohistochemistry. This case illustrates the presentation of this rare type of tumor, and characteristic neuroimaging and pathologic features of MPNSTs.

Oncologic outcomes of sporadic, neurofibromatosis-associated, and radiation-induced malignant peripheral nerve sheath tumors

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNSTs) occur sporadically, after prior radiation therapy (RT), or in association with neurofibromatosis type 1 (NF1). It is controversial whether patients with NF1-associated MPNST have worse outcomes. We investigated the prognostic significance of sporadic, NF1-associated, and RT-induced MPNST.

METHODS

Patients with primary high-grade MPNST from 1982 to 2011 were identified from a prospectively maintained database. Patients with sporadic MPNST were included only if the MPNST was not associated with NF1 or a neurofibroma or if it was immunohistochemically S100-positive.

RESULTS

We studied 105 patients; 42 had NF1-associated tumors, 49 sporadic, and 14 RT-induced. Median age at diagnosis was 38 years. Median follow-up for surviving patients was 4 years. Mean tumor diameter was 5.5 cm for RT-induced tumors and 9.7 cm for NF1-associated and sporadic tumors (P=0.004). In multivariate analysis, factors associated with worse disease-specific survival (DSS) were larger size (HR 1.08; 95% CI 1.04-1.13; P<0.001) and positive margin (HR 3.30; 95% CI 1.74-6.28; P<0.001). Age, gender, site of disease, and S100 staining were not associated with DSS. The 3-year and median DSS were similar for NF1 and sporadic cases; combined 3-year DSS was 64% and median DSS was 8.0 years. For RT-induced tumors, 3-year DSS was 49% and median DSS was 2.4 years. The relationship between RT association and DSS approached statistical significance (HR 2.29; 95% CI 0.93-5.67; P=0.072).

CONCLUSIONS

Margin status and size remain the most important predictors of DSS in patients with MPNST. NF1-associated and sporadic MPNSTs may be associated with improved DSS compared with RT-induced tumors.

Targeting the PI3K/mTOR axis, alone and in combination with autophagy blockade, for the treatment of malignant peripheral nerve sheath tumors

There is a critical need for efficacious therapeutic strategies to improve the outcome of patients afflicted by malignant peripheral nerve sheath tumors (MPNST). Multiple lines of evidence suggest a role for deregulated phosphoinositide 3-kinase (PI3K)/mTOR signaling in MPNST, making this axis an attractive target for therapeutic manipulation. On the basis of previous observations obtained from in vitro experimentation, here we aimed to assess the effects of PI3K/mTOR blockade on MPNST growth in vivo. The anti-MPNST impact of XL765, a dual PI3K/mTOR inhibitor currently being evaluated in human cancer clinical trials, was tested in two human MPNST xenograft models (STS26T and MPNST724) and an experimental model of pulmonary metastasis (STS26T). XL765 abrogated human MPNST local and metastatic growth in severe combined immunodeficient mice. Notably, this therapeutic approach failed to induce apoptosis in MPNST cells but rather resulted in marked productive autophagy. Importantly, genetic and pharmacologic autophagy blockade reversed apoptotic resistance and resulted in significant PI3K/mTOR inhibition-induced MPNST cell death. The addition of the autophagy inhibitor, chloroquine, to the therapeutic regimen of MPNST xenografts after pretreatment with XL765 resulted in superior antitumor effects as compared with either agent alone. Together, preclinical studies described here expand our previous findings and suggest that PI3K/mTOR inhibition alone and (most importantly) in combination with autophagy blockade may comprise a novel and efficacious therapy for patients harboring MPNST.

MicroRNA-204 critically regulates carcinogenesis in malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive soft tissue sarcomas accounting for 3%-10% of all soft tissue sarcomas. Neurofibromatosis type 1 (NF1) is the most important known risk factor. MPNSTs are often diagnosed at an advanced stage when distant metastases have developed. Although surgical resection remains the main treatment for MPNSTs, complete surgical resection is rarely possible. The prognosis for patients with MPNSTs is poor. There is an urgent need for improved therapies. To this end, we investigated whether microRNA (miR), specifically miR-204, might be implicated in MPNSTs because it is located at a cancer-associated genomic region exhibiting high frequency of loss of heterozygosity in tumors. We show that miR-204 expression is downregulated in NF1 and non-NF1 MPNST tumor tissues and in tumor cell lines. Restoring miR-204 expression in MPNST cell lines STS26T (non-NF1), ST88-14 (NF1), and T265p21 (NF1) significantly reduces cellular proliferation, migration, and invasion in vitro. Restoring miR-204 expression in STS26T decreases tumor growth and malignant progression in vivo. We also report that miR-204 inhibits Ras signaling and expression of high mobility group gene A2. These findings support the hypothesis that miR-204 plays critical roles in MPNST development and tumor progression. miR-204 may represent a novel biomarker for diagnosis and a candidate target with which to develop effective therapies for MPNSTs.

Neurogenic tumors of soft tissue

Neurogenic tumors are an uncommon yet important category of soft tissue tumors in children and adolescents because of their frequent association with various genetic syndromes. The heterogeneous cellular composition of the peripheral nerve and the wide metaplastic capacity of the neural crest and its derivatives generate a variety of neoplasms with neurogenic differentiation. This article reviews the clinicopathologic features and differential diagnosis of neurogenic tumors in the first two decades of life, and highlights use of selected ancillary methods for diagnosis.

Telomere maintenance mechanisms in malignant peripheral nerve sheath tumors: expression and prognostic relevance

This study investigated the prevalence and the prognostic relevance of the 2 known telomere maintenance mechanisms (TMMs), telomerase activity (TA) and alternative lengthening of telomeres (ALT), in malignant peripheral nerve sheath tumors (MPNST). In 57 specimens from 49 patients with MPNST (35 sporadic, 14 neurofibromatosis type 1-related), TA was determined using the telomeric repeat amplification protocol, and ALT was detected by assaying ALT-associated promyelocytic leukemia bodies (APB) and terminal restriction fragment (TRF) length distribution. TA or ALT (defined on the basis of APB) alone was found in 24.6% or 26.3% of the lesions, respectively, whereas 6 cases (10.5%) were TA+/ALT+. A concordance between APB and TRF results in defining the ALT status was observed in 44 of 57 cases (77.2%; P < .0001). TA was more frequently expressed in samples from patients with neurofibromatosis type 1 than in those with sporadic disease (60% vs 29.4%, P = 0.087). In the overall series, TA proved to be prognostic for 5-year disease-specific death (hazard ratio, 3.78; 95% confidence interval [CI], 1.60-8.95; P = .002), even when adjusted for the presence of neurofibromatosis type 1 (hazard ratio, 4.22; 95% CI, 1.804-9.874; P = .001) and margin status after surgery (hazard ratio, 5.78; 95% CI, 2.19-15.26; P < .001). Conversely, ALT did not significantly affect clinical outcome of MPNST using either APB expression (hazard ratio, 1.25; 95% CI 0.54-2.89; P = 0.605) or TRF distribution (hazard ratio, 0.57; 95% CI, 0.17-1.96; P = .375) as the detection approach. Our results indicate for the first time that both TMMs, TA and ALT, are present in MPNST and differentially affect patient prognosis.

Survivin is a viable target for the treatment of malignant peripheral nerve sheath tumors

PURPOSE

To examine the role of survivin as a therapeutic target in preclinical models of human malignant peripheral nerve sheath tumors (MPNST) EXPERIMENTAL DESIGN: Survivin protein expression levels and subcellular localization were examined immunohistochemically in an MPNST tissue microarray. Human MPNST cells were studied in vitro and in vivo; real-time PCR, Western blotting, and immunocytochemical analyses were used to evaluate survivin expression and localization activation. Cell culture assays were used to evaluate the impact of anti-survivin-specific siRNA inhibition on cell growth and cell-cycle progression and survival. The effect of the small-molecule survivin inhibitor YM155 on local and metastatic MPNST growth was examined in vivo.

RESULTS

Survivin was found to be highly expressed in human MPNSTs; enhanced cytoplasmic subcellular localization differentiated MPNSTs from their plexiform neurofibroma premalignant counterparts. Human MPNST cell lines exhibited survivin mRNA and protein overexpression; expression in both nuclear and cytoplasmic compartments was noted. Survivin knockdown abrogated MPNST cell growth, inducing G(2) cell-cycle arrest and marked apoptosis. YM155 inhibited human MPNST xenograft growth and metastasis in severe combined immunodeficient (SCID) mice. Antitumor effects were more pronounced in fast-growing xenografts.

CONCLUSIONS

Our studies show an important role for survivin in human MPNST biology. Patients with MPNSTs should be considered for ongoing or future clinical trials that evaluate anti-survivin therapeutic strategies. Most importantly, future investigations should evaluate additional pathways that can be targeted in combination with survivin for maximal synergistic anti-MPNST effects.

Pediatric soft tissue sarcomas

After a brief discussion of the rarity of soft tissue sarcomas in children and of the limited ability of magnetic resonance imaging to provide a tissue diagnosis, this article discusses the incidence, presentation, treatment, prognosis, and imaging characteristics of the more common and unusual pediatric soft tissue sarcomas. It begins with extensive discussion of rhabdomyosarcoma, synovial sarcoma, and congenital/infantile fibrosarcoma. It then presents a more abbreviated discussion of uncommon tumors such as alveolar soft part sarcoma, epithelioid sarcoma, extraosseous Ewing's sarcoma, granulocytic sarcoma, hemangiopericytoma, liposarcoma, malignant fibrous histiocytoma, malignant peripheral nerve sheath tumor, and undifferentiated sarcoma.

Neoplasms associated with germline and somatic NF1 gene mutations

INTRODUCTION

Neurofibromatosis 1 is a tumor predisposition genetic syndrome with autosomal dominant inheritance and virtually 100% penetrance by the age of 5 years. NF1 results from a loss-of-function mutation in the NF1 gene, resulting in decreased levels of neurofibromin in the cell. Neurofibromin is a negative regulator of various intracellular signaling pathways involved in the cellular proliferation. Although the loss of heterozygosity in the NF1 gene may predispose NF1 patients to certain malignancies, additional genetic alterations are a prerequisite for their development. The precise nature of these additional genetic alterations is not well defined, and genetic testing of all malignancies in NF1 patients becomes an essential component of future research in this subset of patients. In addition to germline NF1 mutations, alteration of the somatic NF1 gene is associated with sporadic malignancies such as adenocarcinoma of the colon, myelodysplastic syndrome, and anaplastic astrocytoma.

MATERIALS AND METHODS

A comprehensive English and non-English language search for all articles pertinent to malignancies associated with NF1 was conducted using PubMed, a search engine provided by the U.S. National Library of Medicine and the National Institutes of Health. Key words searched included the following: "malignancies associated with NF1", "tumors associated with NF1", and "NF1 and malignancies". A comprehensive analysis in terms age and mode of presentation, investigation and therapeutic modalities, and outcome of the published data was performed and compared with similar information on the sporadic cases.

RESULTS

Malignancies in NF1 patients typically occur at an earlier age and, with an exception of optic pathway gliomas, certain types of malignancies carry a poor prognosis compared with their sporadic counterparts. Malignancies are the leading cause of death in NF1 patients, resulting in a 10- to 15-year decreased life expectancy compared with the general population.

CONCLUSIONS

The lack of well-defined screening tests for early detection and the nonspecific clinical presentation contributes to a poorer outcome in malignancies associated with NF1. Small study group size, mixed patient population, and a lack of uniformity in reporting research results make comparison of treatment outcome for this group difficult. An International Consensus Meeting to address and recommend best practices for screening, diagnosis, management, and follow-up of malignancies associated with NF1 is needed.

Genomic and molecular characterization of malignant peripheral nerve sheath tumor identifies the IGF1R pathway as a primary target for treatment

PURPOSE

Malignant peripheral nerve sheath tumor (MPNST) is a rare sarcoma that lacks effective therapeutic strategies. We gain insight into the most recurrent genetically altered pathways with the purpose of scanning possible therapeutic targets.

EXPERIMENTAL DESIGN

We conducted a microarray-based comparative genomic hybridization profiling of two cohorts of primary MPNST tissue samples including 25 patients treated at The University of Texas MD Anderson Cancer Center and 26 patients from Tianjin Cancer Hospital. Immunohistochemistry (IHC) and cell biology detection and validation were carried out on human MPNST tissues and cell lines.

RESULTS

Genomic characterization of 51 MPNST tissue samples identified several frequently amplified regions harboring 2,599 genes and regions of deletion including 4,901 genes. At the pathway level, we identified a significant enrichment of copy number-altering events in the insulin-like growth factor 1 receptor (IGF1R) pathway, including frequent amplifications of the IGF1R gene itself. To validate the IGF1R pathway as a potential target in MPNSTs, we first confirmed that high IGF1R protein correlated with worse tumor-free survival in an independent set of samples using IHC. Two MPNST cell lines (ST88-14 and STS26T) were used to determine the effect of attenuating IGF1R. Inhibition of IGF1R in ST88-14 cells using siRNAs or an IGF1R inhibitor, MK-0646, led to significant decreases in cell proliferation, invasion, and migration accompanied by attenuation of the PI3K/AKT and mitogen-activated protein kinase pathways.

CONCLUSION

These integrated genomic and molecular studies provide evidence that the IGF1R pathway is a potential therapeutic target for patients with MPNST.

Early outcomes for malignant peripheral nerve sheath tumor treated with chemotherapy

OBJECTIVES

Malignant peripheral nerve sheath tumors (MPNST) are rare soft-tissue sarcomas with a tendency for recurrence and metastasis. Treatment using chemotherapy is controversial, but benefit with some agents has been described. This study aimed to analyze early survival outcomes using doxorubicin and ifosfamide chemotherapy for MPNST.

METHODS

Pathology records at our musculoskeletal tumor center were searched for patients with a new diagnosis of MPNST between 2003 and 2008. Treatment involved surgical resection, radiation, and chemotherapy with doxorubicin and ifosfamide. Ten patients met inclusion criteria, with mean age 40 years (range, 20-70). Four patients had metastatic disease on presentation. Four patients had neurofibromatosis type I (NF1).

RESULTS

Of 6 patients with nonmetastatic disease on presentation, 5 had no evidence of disease post-treatment. The sixth had positive margins after surgery and initially received no further treatment due to noncompliance. Three from this subgroup developed local recurrence, but none developed distant metastases and 1 died of disease at last follow-up. One- and 2-year disease-free survival (DFS) for this subgroup was 80% and 60%, respectively. One- and 2-year overall survival (OS) for the subgroup was 100%. Of 4 patients with metastatic disease on presentation, 2 had no evidence of disease post-treatment. One of these 2 developed local recurrence, but none from the subgroup developed new metastatic disease. Two of these 4 died of disease at last follow-up. One- and 2-year DFS for this subgroup was 100% and 50%, respectively. One- and 2-year OS was 75% and 50%, respectively. Two of the 4 patients presenting with metastatic disease had NF1. All 3 local recurrences and 2 of the 3 deaths in this study occurred in NF1 patients.

CONCLUSIONS

For all patients, when combined with surgery and radiation, chemotherapy using doxorubicin and ifosfamide yielded 57% DFS and 80% OS at 2 years. NF1 patients appeared to have worse outcomes, with a statistically significantly lower DFS than non-NF1 patients. Limitations of this study include a small sample size, retrospective design, and use of different chemotherapy regimens.

Malignant peripheral nerve sheath tumors (MPNST): the Mayo Clinic experience

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNST) are a rare form of soft tissue sarcoma with few studies reporting on patient outcomes and prognostic variables.

METHODS

A retrospective review of 175 patients diagnosed with MPNST from 1985 to 2010 was performed. Patient, tumor, and treatment characteristics were evaluated to identify prognostic variables.

RESULTS

The median age of our study population was 44 years, and 51% were female. Median tumor size was 6 cm, and 61% of patients had high-grade tumors. Tumors were most commonly located on the extremities (45%), then trunk (34%) and head/neck (19%). The majority of patients underwent surgical resection (95%) and adjuvant treatment with chemotherapy (6%), radiation (42%) or both (22%). Margin status was R0 in 69%, R1 in 2%, R2 in 9%, and unknown in 20%. The local recurrence rate was 22%, and 5- and 10-year disease-specific survival (DSS) were 60% and 45%, respectively. On univariate analysis, no predictors for local recurrence were identified. Tumor size ≥ 5 cm, high tumor grade, tumor location, presence of neurofibromatosis type 1, local recurrence, and adjuvant chemotherapy were all associated with DSS. On multivariate analysis, size ≥ 5 cm [hazard ratio (HR)= 6.1, 95% confidence interval (CI) 1.5-25.0], local recurrence (HR = 4.4, 95% CI 1.7-11.4), high tumor grade (HR = 3.8, 95% CI 1.1-13.2), and truncal location (HR = 3.7, 95% CI 1.1-12.7) were poor prognostic indicators for DSS.

CONCLUSIONS

High tumor grade and tumor size ≥ 5 cm predict adverse DSS for MPNST. In the context of a multidisciplinary treatment regimen, local recurrence and survival outcomes at 5 and 10 years were better than previously reported for MPNST.

Activated MET is a molecular prognosticator and potential therapeutic target for malignant peripheral nerve sheath tumors

PURPOSE

MET signaling has been suggested a potential role in malignant peripheral nerve sheath tumors (MPNST). Here, MET function and blockade were preclinically assessed.

EXPERIMENTAL DESIGN

Expression levels of MET, its ligand hepatocyte growth factor (HGF), and phosphorylated MET (pMET) were examined in a clinically annotated MPNST tissue microarray (TMA) incorporating univariable and multivariable statistical analyses. Human MPNST cells were studied in vitro and in vivo; Western blot (WB) and ELISA were used to evaluate MET and HGF expression, activation, and downstream signaling. Cell culture assays tested the impact of HGF-induced MET activation and anti-MET-specific siRNA inhibition on cell proliferation, migration, and invasion; in vivo gel-foam assays were used to evaluate angiogenesis. Cells stably transduced with anti-MET short hairpin RNA (shRNA) constructs were tested for growth and metastasis in severe combined immunodeficient (SCID) mice. The effect of the tyrosine kinase inhibitor XL184 (Exelixis) targeting MET/VEGFR2 (vascular endothelial growth factor receptor 2) on local and metastatic MPNST growth was examined in vivo.

RESULTS

All three markers were expressed in MPNST human samples; pMET expression was an independent prognosticator of poor patient outcome. Human MPNST cell lines expressed MET, HGF, and pMET. MET activation increased MPNST cell motility, invasion, angiogenesis, and induced matrix metalloproteinase-2 (MMP2) and VEGF expression; MET knockdown had inverse effects in vitro and markedly decreased local and metastatic growth in vivo. XL184 abrogated human MPNST xenograft growth and metastasis in SCID mice.

CONCLUSIONS

Informative prognosticators and novel therapies are crucially needed to improve MPNST management and outcomes. We show an important role for MET in MPNST, supporting continued investigation of novel anti-MET therapies in this clinical context.

Recurring Intracranial Malignant Peripheral Nerve Sheath Tumor: Case Report and Systematic Review of the Literature

BACKGROUND AND IMPORTANCE:

To report the clinical presentation and management of an intracranial frontoparietal malignant peripheral nerve sheath tumor (MPNST) and its recurrence in a 6-year-old girl, along with a systematic review of the literature.

CLINICAL PRESENTATION:

A previously healthy 6-year-old girl presented with severe signs of increased intracranial pressure. Magnetic resonance imaging (MRI) revealed a large heterogeneously enhancing mass at the right frontoparietal convexity. The tumor was completely removed, the histological diagnosis was MPNST, and the patient underwent adjuvant radio- and chemotherapy. Fifteen months later, MRI revealed a small local recurrence. After upfront chemotherapy, the recurrence was removed in a radical, ie, true oncological, neuronavigationally guided, en bloc resection, including approximately 1 cm surrounding gray and white matter and overlying dura mater. Neuropathological examination revealed tumor-free margins. The patient again received adjuvant chemotherapy. Four years after diagnosis and 20 months after cessation of adjuvant therapy, there are no signs of tumor recurrence. The literature search resulted in 17 cases of intracranial MPNSTs not associated with cranial nerves. Despite macroscopically complete resection in many cases and adjuvant radio- and chemotherapy, overall survival was poor, with only 5 patients still alive upon publication (including the current patient).

CONCLUSION:

Intracranial MPNSTs not associated with cranial nerves are extremely rare and highly malignant tumors with poor overall survival, probably because of infiltrating growth into surrounding brain tissue. We therefore advocate consideration of nonconventional true oncological en bloc resection when approaching this rare tumor or its recurrence.

Malignant peripheral nerve sheath tumor arising from the greater omentum: case report

Malignant peripheral nerve sheath tumors (MPNSTs) are rare soft tissue tumors that arise from a peripheral nerve or exhibit nerve sheath differentiation. Most of these tumors arise on the trunk, extremities, or head and neck regions; they are very rarely located in the abdominal cavity. The patient was a 71-year-old man who was referred to our hospital for a mass and pain in the right lower abdomen. Abdominal computed tomography revealed a large (9 × 9 cm), well-circumscribed, lobulated, heterogeneously enhanced mass in the pelvis. Exploratory laparotomy revealed a large mass in the greater omentum, and the tumor was completely excised. Histopathological analysis revealed that the tumor was composed of spindle cells with high mitotic activity. On staining the tumor, positive results were obtained for S-100 but negative results were obtained for c-kit, cluster of differentiation (CD)34, α-smooth muscle actin, and desmin. These findings strongly supported a diagnosis of MPNST primarily arising from the greater omentum. To the best of our knowledge, this is the first reported case of an MPNST arising from the greater omentum. In this report, we have described the case of a patient with an MPNST arising from the greater omentum and have discussed the clinical characteristics and management of MPNSTs.

Array-based comparative genomic hybridization identifies CDK4 and FOXM1 alterations as independent predictors of survival in malignant peripheral nerve sheath tumor

PURPOSE

Malignant peripheral nerve sheath tumors (MPNST) are highly aggressive sarcomas with variable patient survival and few known prognostically relevant genomic biomarkers. To identify survival-associated genomic biomarkers, we performed high-resolution array-based comparative genomic hybridization (aCGH) on a large set of MPNSTs.

EXPERIMENTAL DESIGN

Candidate gene alterations identified by aCGH in 38 MPNSTs were validated at the DNA, RNA, and protein levels on these same tumors and an independent set of 87 MPNST specimens.

RESULTS

aCGH revealed highly complex copy number alterations, including both previously reported and completely novel loci. Four regions of copy number gain were associated with poor patient survival. Candidate genes in these regions include SOX5 (12p12.1), NOL1 and MLF2 (12p13.31), FOXM1 and FKBP1 (12p13.33), and CDK4 and TSPAN31 (12q14.1). Alterations of these candidate genes and several others of interest (ERBB2, MYC and TP53) were confirmed by at least 1 complementary methodology, including DNA and mRNA quantitative real-time PCR, mRNA expression profiling, and tissue microarray-based fluorescence in situ hybridization and immunohistochemistry. Multivariate analysis showed that CDK4 gain/amplification and increased FOXM1 protein expression were the most significant independent predictors for poor survival in MPNST patients (P < 0.05).

CONCLUSIONS

Our study provides new and independently confirmed candidate genes that could serve as genomic biomarkers for overall survival in MPNST patients.

Prognostic significance of p14ARF, p15INK4b, and p16INK4a inactivation in malignant peripheral nerve sheath tumors

PURPOSE

p14(ARF), p15(INK4b), and p16(INK4a) are tumor suppressor genes that are located closely at 9p21 and are often coinactivated by genetic or epigenetic alterations. Malignant peripheral nerve sheath tumor (MPNST) is a rare sarcoma with poor prognosis. However, the prognostic implications of inactivation of p14(ARF), p15(INK4b), and p16(INK4a) in MPNSTs have not been adequately investigated. Here we carried out a genetic, epigenetic, and expression analysis of p14(ARF), p15(INK4b), and p16(INK4a), and clarified the prognostic significance of their inactivation in MPNSTs.

EXPERIMENTAL DESIGN

p14(ARF), p15(INK4b), and p16(INK4a) protein expressions were assessed by immunohistochemistry in 129 formalin-fixed samples of MPNST including 85 primary tumors. Thirty-nine samples, for which frozen material was available, were also investigated by Western blotting and quantitative reverse transcription PCR (RT-PCR) to detect p14(ARF), p15(INK4b), and p16(INK4a) protein and mRNA expression, and by multiplex real-time PCR, PCR single strand conformation polymorphism and methylation-specific PCR to detect p14(ARF), p15(INK4b), and p16(INK4a) gene alterations.

RESULTS

Immunohistochemically decreased expressions of p14(ARF), p15(INK4b), and p16(INK4a) were observed in 48%, 54%, and 49% of primary MPNSTs, respectively, and were significantly correlated with their concordant mRNA levels. As for gene alterations, homozygous deletion of CDKN2A was detected in one third of the cases. Inactivation of p14(ARF) and p16(INK4a) was associated with poor prognosis by both univariate and multivariate analyses. Furthermore, cases with inactivation of all p14(ARF), p15(INK4b), and p16(INK4a) genes showed the worst prognosis in a combined prognostic assessment.

CONCLUSION

A comprehensive analysis of p14(ARF), p15(INK4b), and p16(INK4a) inactivation status provides useful prognostic information in MPNSTs.

Clinical sonopathology for the regional anesthesiologist: part 1: vascular and neural

The use of ultrasound to facilitate regional anesthesia is an evolving area of clinical, education, and research interests. As our community's experience grows, it has become evident that anesthesiologists performing "routine" ultrasound-guided blocks may very well be confronted with atypical or even pathologic anatomy. As an educational resource for anesthesiologists, the following articles present examples of common sonopathology that may be encountered during ultrasound-guided regional anesthesia. This present article describes sonopathology related to blood vessels and nerves.

A small intraneural epithelioid malignant peripheral nerve sheath tumour of the median nerve simulating a benign lesion: description of a case and review of the literature

The epithelioid variant of malignant peripheral nerve sheath tumours (MPNSTs) is a very rare malignancy. We describe the case of a 30-year-old man complaining of acute pain in his right elbow, mild distal paraesthesias, and some motor deficiencies. He was discovered as having a small fusiform swelling of the median nerve. In view of its very small size, shape, and nonspecific MRI signal, it had initially suggested a benign lesion. The diagnosis of epithelioid MPNST was made only at the histopathological examination. This malignant neoplasm recurred locally fourteen months after surgery. In addition to describe the above very rare case, we have reviewed the literature on epithelioid MPNSTs clearly involving deep major nerve trunks. This case serves as a warning that, even in major nerve trunks, tiny lesions may in reality be early intraneural MPNSTs which, due to their deep location, must be treated adequately with wide margin surgery since the resection margin status represents one of the major parameters influencing the local control of disease and its clinical outcome.

[Malignant peripheral nerve sheath tumors: A case report]

Malignant peripheral nerve sheath tumors comprehend a rare group of soft tissue sarcomas that tend to occur in patients with neurofibromatosis type 1 or several years after radiotherapy treatments. Its thoracic localization is a very unusual entity. The typical symptoms are due to nerve roots compression which can persist for several months or years before diagnosis. Due to very few patients with this type of tumor its therapeutic approach is still a matter of permanent debate, being surgery the main treatment. This tumor has a bad prognosis because of high local recurrence and metastasis. The clinical case we describe serves as a glimpse for discussion.

Factors of influence upon overall survival in the treatment of intracranial MPNSTs. Review of the literature and report of a case

BACKGROUND

Intracranial malignant peripheral nerve sheath tumors are rare entities that carry a poor prognosis. To date, there are no established therapeutic strategies for these tumors.

METHODS

We review the present treatment modalities and present the current therapeutic dilemmas. We perform a statistical analysis to evaluate the prognostic factors for Overall Survival of these patients. Additionally, we present our experience with a 64-year-old man with a MPNST of the left cerebellopontine angle.

RESULTS

To our best knowledge, forty three patients with intracranial MPNSTs, including our case, have been published in the international literature. Our analysis showed gross total resection, radiotherapy and female gender to be beneficial prognostic factors of survival in the univariate analysis. Gross total resection was recognized as the only independent predictor of prolonged Overall Survival. In our case, we performed a gross total resection followed for the first time by stereotactically guided radiotherapy.

CONCLUSION

Considering the results of the statistical analysis and the known advantages of the stereotaxy, we suggest aggressive surgery followed by stereotactically guided radiotherapy as therapy of choice.

Autophagic survival in resistance to histone deacetylase inhibitors: novel strategies to treat malignant peripheral nerve sheath tumors

Histone deacetylase inhibitors (HDACi) show promise as cancer therapeutics; however, the full scope of their utility remains unknown. Here we report findings that strongly rationalize clinical evaluation of HDACis in malignant peripheral nerve sheath tumors (MPNST), a class of highly aggressive, therapeutically resistant, and commonly fatal malignancies that occur sporadically or in patients with the inherited neurofibromatosis type-1 (NF1) syndrome. We evaluated the effects of the chemical HDACis PCI-24781, suberoylanilide hydroxamic acid, and MS-275 on a panel of human NF1-associated and sporadic MPNSTs in vitro and in vivo. A subset of MPNSTs was found to be highly sensitive to HDACis, especially to PCI-24781. All cell lines in this group were NF1-associated. Significant proapoptotic effects were noted in vitro and in vivo and were independent of p53 mutational status. In contrast, as a group the sporadic-MPNST cells were markedly resistant to HDACi treatment. HDACis were found to induce productive autophagy in MPNST cells. Genetic and/or pharmacologic autophagy blockade resulted in significant HDACi-induced apoptosis in cells defined as resistant or sensitive, leading to abrogated growth of primary tumors and lung metastases in tumor xenograft assays. Among autophagy-associated genes expressed in response to HDACi, the immunity-related GTPase family, M was validated as a critical target in mediating HDACi-induced autophagy and enhanced apoptosis. Taken together, our findings strongly support the evaluation of HDACi currently in clinical trials as an important new therapeutic strategy to treat MPNST, including in combination with autophagy blocking combination regimens in particular for patients with sporadic MPNST.

Morbidity and functional status of patients with pelvic neurogenic tumors after wide excision

BACKGROUND

We previously reported that over the last 10 years our practice has evolved in the treatment of neurogenic tumors of the pelvis to include a multispecialty team of surgeons, a factor that might decrease morbidity and improve recurrence, survival, and function.

QUESTIONS/PURPOSES

Therefore, we (1) assessed the morbidity associated with surgical excision in patients with neurogenic tumors of the pelvis; (2) determined the function of these patients; and (3) determined the rates of local recurrence, metastasis, and overall survival with this new approach.

METHODS

We reviewed the records of all 38 patients who had surgery for a pelvic plexus tumor between 1994 and 2005. Twenty one were male. The mean age of all patients was 38 years and median follow up was 2.1 years. Twelve patients had a malignant tumor. We recorded demographic data, postoperative complications, tumor-specific recurrence, and determined survival.

RESULTS

Postoperative complications occurred in nine of the 38 patients (23%): hematoma (n = 3), wound infection or deep abscess (n = 3), and deep venous thrombosis (n = 3). Surgical complications occurred more frequently in patients with malignant disease. Patients with benign tumors had a mean MSTS score of 94%, while survivors of malignant disease had a mean of 57%. For malignant tumors, the 5-year rate of local recurrence was 40%, the estimated 5-year rate of metastasis was 67% and 5-year survival rate was 50%.

CONCLUSION

Using a team approach, surgical excision provided high functional scores for patients with benign disease with a low rate of complications. In patients with malignant tumors, intentional wide resection is associated with higher morbidity but yields acceptable functional scores.

First-line chemotherapy for malignant peripheral nerve sheath tumor (MPNST) versus other histological soft tissue sarcoma subtypes and as a prognostic factor for MPNST: an EORTC soft tissue and bone sarcoma group study

BACKGROUND

the role of chemotherapy in advanced malignant peripheral nerve sheath tumor (MPNST) is unclear.

PATIENTS AND METHODS

chemotherapy-naive soft tissue sarcomas (STS) patients treated on 12 pooled nonrandomized and randomized European Organization for Research and Treatment of Cancer Soft Tissue and Bone Sarcoma Group trials were retrospectively analyzed. Clinical outcomes, overall survival, progression-free survival (PFS) and response were determined for MPNST and other STS histotypes and compared. Additionally, prognostic factors within the MPNST population were defined. Studied cofactors were demographics, sarcoma history, disease extent and chemotherapy regimen.

RESULTS

after a median follow-up of 4.1 years, 175 MPNST out of 2675 eligible STS patients were analyzed. Outcome was similar for MPNST versus other STS histotypes, with a response rate, median PFS and overall survival of 21% versus 22%, 17 versus 16 weeks and 48 versus 51 weeks, respectively. Performance status was an independent prognostic factor for overall survival. Chemotherapy regimen was an independent prognostic factor for response (P < 0.0001) and PFS (P = 0.009). Compared with standard first-line doxorubicin, the doxorubicin-ifosfamide regimen had the best response, whereas ifosfamide had the worst prognosis.

CONCLUSION

this series indicates the role of chemotherapy in treatment of advanced MPNST. This first comparison showed similar outcomes for MPNST and other STS histotypes. The apparent superiority of the doxorubicin-ifosfamide regimen justifies further investigations of this combination in randomized trials.

Primary intracranial malignant peripheral nerve sheath tumour responding to chemotherapy

Malignant peripheral nerve sheath tumours (MPNST) are a rare variety of soft tissue sarcomas (STS) arising from major peripheral nerve branches and typically located in the lower extremity, chest wall or the retroperitoneum. It is a biologically aggressive neoplasm for which the treatment of choice is surgery, but usually requires a multimodality approach, having been generally labelled as chemoresistant. We present a case of MPNST located intracranially with a good response to chemotherapy.

Malignant peripheral nerve cell sheath tumour of the upper lip: a rare case

We present the case of a malignant peripheral nerve sheath tumour (MPNST) that developed on the upper lip of an 86 year old woman. MPNSTs are highly aggressive sarcomas that very rarely occur in the face. We know of no other reported cases of a malignant peripheral nerve sheath tumour arising from the upper lip.

MRI features in the differentiation of malignant peripheral nerve sheath tumors and neurofibromas

OBJECTIVE

The objective of this study was to identify the MRI criteria that best differentiate malignant peripheral nerve sheath tumors from benign neurofibromas.

MATERIALS AND METHODS

We retrospectively analyzed MR images obtained for 41 histologically diagnosed cases of malignant peripheral nerve sheath tumor and 20 cases of neurofibroma that had been treated at four tertiary institutions. Twenty of the patients with malignant peripheral nerve sheath tumors and 14 patients with neurofibromas developed the disease in association with neurofibromatosis 1. The MR images were evaluated with regard to tumor size, signal intensity, heterogeneity of T1- and T2-weighted MR images, enhancement pattern, definition of margins, presence of perilesional edemalike zone, and presence of intratumoral cystic lesions.

RESULTS

Significant differences between malignant peripheral nerve sheath tumors and neurofibromas were noted for the largest dimension of the mass, peripheral enhancement pattern, perilesional edemalike zone, and intratumoral cystic lesion. In cases associated with neurofibromatosis 1, heterogenicity on T1-weighted images was also significant in differentiating neurofibroma from malignant peripheral nerve sheath tumor. The presence of two or more of the four features suggestive of malignancy indicated malignant peripheral nerve sheath tumor with a sensitivity of 61% and a specificity of 90%.

CONCLUSION

The MR features described in this study are useful for distinguishing malignant peripheral nerve sheath tumors from neurofibromas. If a tumor has two or more of the four statistically significant features, it can be considered to be highly suspicious of malignancy and should be subjected to a biopsy for early diagnosis.

The Surgical Management of Symptomatic Peripheral Nerve Sheath Tumors

OBJECTIVE

To determine the clinical presentation and morbidity of the surgical management of peripheral nerve sheath tumors (PNSTs).

METHODS

We performed a retrospective chart review of surgically treated PNSTs at the University of Miami between 1991 and 2008.

RESULTS

There were a total of 140 cases, including 87 schwannomas, 34 neurofibromas, and 19 malignant peripheral nerve sheath tumors (MPNSTs). The average age of the total study group was 49.0 years; it was significantly lower for patients with neurofibroma. There was a high correlation between neurofibroma tumors and neurofibromatosis-1. Most patients with benign tumors presented with a painful mass, paresthesias, or numbness without significant weakness. Patients who had previously undergone attempted resections and preoperative biopsy had a significantly increased risk (41%) for developing postoperative neurologic deficits when compared with patients who presented with de novo tumors (15%). Intraoperative monitoring appeared to reduce the risk of postoperative motor deficit, particularly in neurofibromas. Most MPNSTs (&gt;80%) were diagnosed at stage IIB or higher and had a combined mortality rate of 31.6% at 78 months. Tumor size was the best predictor of adverse outcome, as all MPNST mortalities occurred in patients with a tumor size of more than 7 cm.

CONCLUSION

PNSTs are a heterogeneous group of lesions. Benign tumors respond well to marginal excision, whereas MPNSTs are aggressive sarcomas that require multimodal management. There was a significantly increased risk of postoperative neurologic deficits in patients who had undergone a previous biopsy, and thus tertiary referral without biopsy is recommended when a PNST is suspected.

Potential role of 18fluorodeoxyglucose-positron emission tomography/computed tomography in differentiating benign neurofibroma from malignant peripheral nerve sheath tumor associated with neurofibromatosis 1

OBJECTIVE

Benign plexiform neurofibromas (PNfib), especially those occurring in patients with neurofibromatosis type 1, are at a significant risk of progressing to a malignant peripheral nerve sheath tumor (MPNST). Early diagnosis, followed by radical surgery and adjuvant radiation to maintain local tumor control, is of critical importance to prevent metastasis and subsequent mortality from MPNSTs. However, early diagnosis is hampered by the sensitivity of current imaging modalities such as computed tomography (CT) or magnetic resonance imaging to reliably detect this malignant transformation, which can occur heterogeneously in a PNfib to a MPNST. 18Fluorodeoxyglucose (18FDG)-positron emission tomography (PET) is linked to metabolism and proliferation of tissues and has been widely used in oncology including PNSTs. 18FDG-PET/CT has the added advantage of fusing metabolic and anatomic imaging data sets.

METHODS

In this prospective study, 9 neurofibromatosis type 1-associated PNfibs suspected to have undergone transformation to an MPNST were preoperatively evaluated by 18FDG-PET/CT and magnetic resonance imaging. A detailed histological evaluation correlated the average and regional standard uptake value (SUV) from the 18FDG-PET/CT to grade of malignancy of the suspected MPNST.

RESULTS

Imaging from 18FDG-PET/CT and associated SUV of the suspected MPNSTs demonstrated either a homogeneous or a heterogeneous pattern. Stratification of the maximal SUV to low (<4.0), intermediate (4.0-7.0), or high (>7.0) correlated to the proliferative index (Ki-67) and grade of MPNST. A maximal SUV of more than 7.0 was closely correlated to a focus of malignant transformation.

CONCLUSION

This study, on a limited number of cases, demonstrates the potential use of 18FDG-PET/CT to augment management of PNfibs, especially in the context of neurofibromatosis type 1, which is characterized by multiple tumors. The addition of CT anatomic imaging to 18FGD-PET can facilitate targeting biopsies to metabolic hot spots, to further augment diagnostic sensitivity. Much larger numbers of MPNSTs, which can only be accrued in a collaborative manner among institutions, are required to further assess the specificity and sensitivity of 18FDG-PET/CT in the diagnosis of MPNSTs.

Genomic changes in chromosomes 10, 16, and X in malignant peripheral nerve sheath tumors identify a high-risk patient group

PURPOSE

The purpose of this study was to identify genetic aberrations contributing to clinical aggressiveness of malignant peripheral nerve sheath tumors (MPNSTs).

PATIENTS AND METHODS

Samples from 48 MPNSTs and 10 neurofibromas were collected from 51 patients with (n = 31) or without (n = 20) neurofibromatosis type 1 (NF1). Genome-wide DNA copy number changes were assessed by chromosomal and array-based comparative genomic hybridization (CGH) and examined for prognostic significance. For a subset of 20 samples, RNA microarray data were integrated with the genome data to identify potential target genes.

RESULTS

Forty-four (92%) MPNSTs displayed DNA copy number changes (median, 18 changes per tumor; range, 2 to 35 changes). Known frequent chromosomal gains at chromosome arms 8q (69%), 17q (67%), and 7p (52%) and losses from 9p (50%), 11q (48%), and 17p (44%) were confirmed. Additionally, gains at 16p or losses from 10q or Xq identified a high-risk group with only 11% 10-year disease-specific survival (P = .00005). Multivariate analyses including NF1 status, tumor location, size, grade, sex, complete remission, and initial metastatic status showed that the genomic high-risk group was the most significant predictor of poor survival. Several genes whose expression was affected by the DNA copy number aberrations were identified.

CONCLUSION

The presence of specific genetic aberrations was strongly associated with poor survival independent of known clinical risk factors. Conversely, within the total patient cohort with 34% 10-year disease-specific survival, a low-risk group was identified: without changes at chromosomes 10q, 16p, or Xq in their MPNSTs, the patients had 74% 10-year survival.

PDGFRA, PDGFRB, EGFR, and downstream signaling activation in malignant peripheral nerve sheath tumor

We investigated the activation of platelet-derived growth factor (PDGF) receptor A (PDGFRA), PDGF receptor B (PDGFRB), epidermal growth factor receptor (EGFR), and their downstream pathways in malignant peripheral nerve sheath tumors (MPNSTs). PDGFRA, PDGFRB, and EGFR were immunohistochemically, biochemically, cytogenetically, and mutationally analyzed along with the detection of their cognate ligands in 16 neurofibromatosis type 1 (NF1)-related and 11 sporadic MPNSTs. The activation of the downstream receptor pathways was also studied by means of v-akt murine thymoma viral oncogene homolog (AKT), extracellular signal-regulated kinase (ERK), and mammalian target of rapamycin (mTOR) Western blotting experiments, as well as rat sarcoma viral oncogene homolog (RAS), v-raf murine sarcoma viral oncogene homolog B1 (BRAF), phosphoinositide-3-kinase, catalytic, alpha polypeptide (PI3KCA), and phosphatase and tensin homolog deleted on chromosome ten (PTEN) mutational analysis and fluorescence in situ hybridization. PDGFRA, PDGFRB, and EGFR were expressed/activated, with higher levels of EGFR expression/phosphorylation paralleling increasing EGFR gene copy numbers in the NF1-related cases (71%). Autocrine loop activation of these receptors along with their coactivation were suggested by the expression of the cognate ligands in the absence of mutations and the presence of receptor tyrosine kinase (RTK) heterodimers, respectively. Both MPNST groups showed AKT, ERK, and mTOR expression/phosphorylation. No BRAF, PI3KCA, or PTEN mutations were found in either group of MPNSTs, but 18% of the sporadic MPNSTs showed RAS mutations. PTEN monosomy segregated with the NF1-related cases (50%, p = 0.018), but PTEN protein was expressed in all but two cases. In conclusion, PDGFRA, PDGFRB, and EGFR seem to be promising molecular targets for tailored treatments in MPNST. In particular, the ligand- and heterodimerization-dependent RTK activation/expression coupled with a downstream signaling phosphorylation, mediated by the upstream receptors or RAS activation, may provide a rationale to apply combined RTK and mTOR inhibitor treatments both to sporadic and NF1-related cases.

[Surgical treatment of musculoskeletal soft tissue sarcomas]

Treatment of soft tissue sarcomas requires an individual plan which considers interdisciplinary recommendations and the various clinical situations. Anatomical region, histological grading and typing, and tumor size necessitate adjusted methods of reconstruction. The biopsy should be performed at the institution where the patient is treated. In general surgical resection of the tumor will be the treatment of choice. Adjuvant therapies are applied according to anatomical region and size and grading of the tumor. Surgery alone is recommended only in small (<5 cm), superficial, low-grade sarcomas. Sarcomas larger than 5 cm in diameter should be treated by surgery and radiotherapy, achieving excellent results, although in high-grade sarcomas more than 50% of patients still will experience metastatic disease. In case of locally recurrent disease, surgical revision with tumor-free resection margins followed by radiotherapy should be the aim. This applies even for patients who had had radiotherapy after the first excision. In this case brachytherapy is a good modality of tissue-sparing treatment.

Malignant peripheral nerve sheath tumour (MPNST): the clinical implications of cellular signalling pathways

Malignant peripheral nerve sheath tumour (MPNST) is a rare malignancy accounting for 3–10% of all soft tissue sarcomas. Most MPNSTs arise in association with peripheral nerves or deep neurofibromas and may originate from neural crest cells, although the specific cell of origin is uncertain. Approximately half of MPNSTs occur in the setting of neurofibromatosis type 1 (NF1), an autosomal dominant disorder with an incidence of approximately one in 3500 persons; the remainder of MPNSTs develop sporadically. In addition to a variety of clinical manifestations, approximately 8–13% of NF1 patients develop MPNSTs, which are the leading cause of NF1-related mortality. Surgical resection is the mainstay of MPNST clinical management. However, because of invasive growth, propensity to metastasise, and limited sensitivity to chemotherapy and radiation, MPNST has a guarded to poor prognosis. Five-year survival rates of only 20–50% indicate an urgent need for improved therapeutic approaches. Recent work in this field has identified several altered intracellular signal transduction cascades and deregulated tyrosine kinase receptors, posing the possibility of personalised, targeted therapeutics. However, expanded knowledge of MPNST molecular pathobiology will be needed to meaningfully apply such approaches for the benefit of afflicted patients.

Primary pediatric intraspinal sarcomas. Report of 3 cases

Sarcomas that arise from within the spinal canal are rare, particularly within the pediatric population. In general, these primary intraspinal sarcomas are highly aggressive, posing unique treatment challenges with respect to surgery and choice of adjuvant therapy. The goal must be to obtain the most complete resection possible to minimize the risk of recurrence and metastasis, while preventing potential neurological deficits that may result from aggressive surgery. Among these primary intraspinal sarcomas are malignant peripheral nerve sheath tumors and members of the Ewing sarcoma family of tumors. The authors present 3 cases of unique spinal sarcomas in children-2 malignant peripheral nerve sheath tumors in patients without neurofibromatosis and an intradural extraosseous Ewing sarcoma arising from the sensory component of a lumbar spinal nerve-and discuss their management and outcome with a review of the current literature.