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Concept: Malignant peripheral nerve sheath tumor


Neurofibromatosis type 1 (NF1) patients develop benign neurofibromas and malignant peripheral nerve sheath tumors (MPNST). These incurable peripheral nerve tumors result from loss of NF1 tumor suppressor gene function, causing hyperactive Ras signaling. Activated Ras controls numerous downstream effectors, but specific pathways mediating the effects of hyperactive Ras in NF1 tumors are unknown. We performed cross-species transcriptome analyses of mouse and human neurofibromas and MPNSTs and identified global negative feedback of genes that regulate Ras/Raf/MEK/ERK signaling in both species. Nonetheless, ERK activation was sustained in mouse and human neurofibromas and MPNST. We used a highly selective pharmacological inhibitor of MEK, PD0325901, to test whether sustained Ras/Raf/MEK/ERK signaling contributes to neurofibroma growth in a neurofibromatosis mouse model (Nf1fl/fl;Dhh-Cre) or in NF1 patient MPNST cell xenografts. PD0325901 treatment reduced aberrantly proliferating cells in neurofibroma and MPNST, prolonged survival of mice implanted with human MPNST cells, and shrank neurofibromas in more than 80% of mice tested. Our data demonstrate that deregulated Ras/ERK signaling is critical for the growth of NF1 peripheral nerve tumors and provide a strong rationale for testing MEK inhibitors in NF1 clinical trials.

Concepts: Gene, Cancer, Oncology, Action potential, Enzyme inhibitor, Neurofibromatosis, Malignant peripheral nerve sheath tumor, Nerve sheath tumor


ABSTRACT:: Desmoplastic melanoma (DM) presents diagnostic challenges due to histologic mimics and limited immunohistochemical staining. Although S100 usually stains DM, other melanoma markers (HMB-45 and Melan-A) are often negative. Dermal/subcutaneous mimics of DM [spindle cell/poorly differentiated squamous cell carcinoma, atypical fibroxanthoma (AFX), and sarcoma] show negative or unreliable immunohistochemical staining. Recently, SOX10 expression has been shown to be a sensitive and specific marker of DM. However, there are no published studies comparing the sensitivity and specificity of SOX10 for DM compared with its most common histologic mimics of the dermis/subcutis. We examined 76 cases, including DM (n = 15), spindle cell/poorly differentiated carcinoma (n = 18), AFX (n = 13), sarcoma with spindled morphology (n = 20), and malignant peripheral nerve sheath tumor (MPNST) (n = 10). Most (75%, 15/20) of sarcomas were centered in the dermis/subcutis and included sarcoma not otherwise specified, DFSP with sarcomatous transformation and myxofibrosarcoma. SOX10 was diffusely positive in 100% (15/15) of DMs and showed focal staining in 30% (3/10) of MPNSTs. All other tumors were negative for SOX10 [0% (0/18) of carcinomas, 0% (0/13) of AFXs, 0% (0/20) of sarcomas]. In conclusion, SOX10 is a highly useful marker to confirm the diagnosis of DM. In our study, SOX10 showed 100% sensitivity for DM and SOX10 was negative in all histologic mimics of the dermis/subcutis, including spindle cell carcinoma, AFX and sarcomas. Similar to S-100 protein, some MPNSTs show scattered positivity but did not show diffuse positivity seen in DM.

Concepts: Cancer, Sensitivity and specificity, Anatomical pathology, Types of cancer, Carcinoma, Squamous cell carcinoma, Sarcoma, Malignant peripheral nerve sheath tumor


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.

Concepts: Cancer, Oncology, Survival analysis, Action potential, Multivariate statistics, Malignant peripheral nerve sheath tumor, Nerve sheath tumor, Peripheral nervous system


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.

Concepts: Medicine, Cancer, Oncology, Medical terms, Action potential, Neurofibromatosis type I, Malignant peripheral nerve sheath tumor, Nerve sheath tumor


The aim of this study was to compare the diagnostic performance of F-fluorodeoxyglucose (FDG) PET/CT and whole-body MRI for the detection of malignant peripheral nerve sheath tumors (MPNSTs) in patients with neurofibromatosis type 1, and to evaluate a panel of imaging-based criteria serving that purpose.

Concepts: Oncology, Medical terms, Action potential, Malignant peripheral nerve sheath tumor, Nerve sheath tumor, Fludeoxyglucose


The objective of this study was to establish a simple and rapid immunocytochemical technique that can be used in veterinary diagnostic cytology. Air-dried impression smears were collected from canine tumors. Samples of epithelial tumors, mesenchymal tumors, and malignant peripheral nerve sheath tumors and melanomas were used for detection of cytokeratin, vimentin, and S-100 protein, respectively. The labeled streptavidin-biotin system was used in the present study. Optimal fixation was determined using standard immunocytochemical procedures, and acetone fixation was found to be the most effective. Optimal concentrations of primary and secondary antibodies were determined at a preset 5-min incubation. Omission of H2O2 treatment, shortening the time for blocking and labeled-streptavidin incubation, and simplifying washing did not decrease immunopositive intensities or enhance false-positive reactions. The described rapid protocol requires approximately 45 min without the use of any special equipment.

Concepts: Present, Time, Oncology, Action potential, Tumor, Immunohistochemistry, Malignant peripheral nerve sheath tumor, Nerve sheath tumor


MicroRNAs (miRNAs) are a class of non-coding RNA, which have recently been shown to have a wide variety of regulatory functions in relation to gene expression. Since their identification nearly 20 years ago, miRNAs have been found to play an important role in cancer, including in neurofibromatosis type 1 (NF1)-associated tumours. NF1 is the most commonly inherited tumour predisposition syndrome and can lead to malignancy via the development of malignant peripheral nerve sheath tumours (MPNSTs). Although the mechanisms by which benign neurofibromas develop into MPNSTs still remain to be elucidated, it is becoming increasingly clear that miRNAs play a key role in this process and have the potential to be used as both diagnostic and prognostic markers of tumorigenesis.

Concepts: DNA, Gene, Gene expression, Cancer, Oncology, RNA, Malignant peripheral nerve sheath tumor, Nerve sheath tumor


Background:Neurofibromatosis type 1 is one of the most common familial diseases, the hallmark of which is the development of multiple neurofibromas. These are benign nerve sheath tumours, which can transform into malignant peripheral nerve sheath tumours (MPNST).Methods:The aim of this study was to identify differentially expressed microRNA (miRNA) in neurofibromas and MPNST obtained from patients with neurofibromatosis type 1 using microarray analysis. Differential expression was validated by reverse transcription quantitative-PCR, and functional studies were performed after transfection of miRNA oligonucleotide mimics into MPNST cells.Results:Sixteen miRNA were significantly differentially expressed in MPNST compared with NF, and of these fourteen were downregulated in MPNST: these included miR-30e*, miR-29c*, miR-29c, miR-340*, miR-30c, miR-139-5p, miR-195, miR-151-5p, miR-342-5p, miR-146a, miR-150, miR-223, let-7 a and let-7 g with a false discovery rate of q=8.48E-03 for the least significant miRNA. In contrast, miR-210 and miR-339-5p were upregulated in MPNST compared with neurofibromas. Prediction softwares/algorithms identified a list of genes targeted by miR-29c including extracellular matrix genes and matrix metalloproteinase (MMP)-2, all of which are reported to be involved in cell migration and invasion. Functional studies in a MPNST cell line, sNF96.2, using a mimic of the mature miR-29c showed reduced invasion, whereas there was no change in proliferation. Zymography of the manipulated cells showed that MMP2 activity was also reduced when miR-29c expression was forced in sNF96.2.Conclusion:We provide evidence that reduction of miR-29c has a pivotal role in the progression of nerve sheath tumours and results by increasing the invasive/migratory properties of nerve sheath tumours.British Journal of Cancer advance online publication, 22 November 2012; doi:10.1038/

Concepts: Gene, Gene expression, Cancer, Oncology, RNA, Matrix metalloproteinase, Malignant peripheral nerve sheath tumor, Nerve sheath tumor


Malignant peripheral nerve sheath tumors (MPNSTs) are rare soft tissue sarcomas that arise from peripheral nerve fibers and are derived from Schwann cells, perineural cells, or fibroblasts. MPNST is an aggressive neoplasm in which local recurrence is common and complete excision of the mass should be the goal of surgery. We report a case of MPNST involving the penis in a 14-month-old boy. This is only the second reported case of penile MPNST without evidence of neurofibromatosis 1 and the first of which to occur in a patient this young.

Concepts: Cancer, Oncology, Soft tissue sarcoma, Action potential, Neoplasm, Axon, Malignant peripheral nerve sheath tumor, Nerve sheath tumor


About 50% of all malignant peripheral nerve sheath tumors (MPNSTs) arise as neurofibromatosis type 1 associated lesions. In those patients malignant peripheral nerve sheath tumors are thought to arise through malignant transformation of a preexisting plexiform neurofibroma. The molecular changes associated with this transformation are still poorly understood. We sought to test the hypothesis that dysregulation of expression of kinases contributes to this malignant transformation. We analyzed expression of all 519 kinase genes in the human genome using the nanostring nCounter system. Twelve cases of malignant peripheral nerve sheath tumor arising in a background of preexisting plexiform neurofibroma were included. Both components were separately sampled. Statistical analysis compared global changes in expression levels as well as changes observed in the pairwise comparison of samples taken from the same surgical specimen. Immunohistochemical studies were performed on tissue array slides to confirm expression of selected proteins. The expression pattern of kinase genes can separate malignant peripheral nerve sheath tumors and preexisting plexiform neurofibromas. The majority of kinase genes is downregulated rather than overexpressed with malignant transformation. The patterns of expression changes are complex without simple recurring alteration. Pathway analysis demonstrates that differentially expressed kinases are enriched for kinases involved in the direct regulation of mitosis, and several of these show increased expression in malignant peripheral nerve sheath tumors. Immunohistochemical studies for the mitotic regulators BUB1B, PBK and NEK2 confirm higher expression levels at the protein level. These results suggest that the malignant transformation of plexiform neurofibroma is associated with distinct changes in the expression of kinase genes. The patterns of these changes are complex and heterogeneous. There is no single unifying alteration. Kinases involved in mitotic regulation are particularly enriched in the pool of differentially expressed kinases. Some of these are overexpressed and are therefore possible targets for kinase inhibitors.Modern Pathology advance online publication, 1 February 2013; doi:10.1038/modpathol.2012.242.

Concepts: Gene expression, Cancer, Oncology, Human genome, Neurofibromatosis, Malignant peripheral nerve sheath tumor, Nerve sheath tumor, Neurofibroma