Chromosomal imbalances in malignant peripheral nerve sheath tumor detected by metaphase and microarray comparative genomic hybridization

Malignant peripheral nerve sheath tumors (MPNSTs) are highly malignant tumors affecting adolescents and adults. There have been a few reports on chromosomal aberrations of MPNSTs; however, the tumor-specific alteration remains unknown. We characterized the genomic alterations in 8 MPNSTs and 8 schwannomas by metaphase comparative genomic hybridization (CGH). In 5 of 8 MPNSTs, microarray CGH was added for more detailed analyses. Frequent gains were identified on 3q13-26, 5p13-14, and 12q11-23 and frequent losses were at 1p31, 10p, 11q24-qter, 16, and 17. Microarray CGH revealed frequent gains of EGFR, DAB2, MSH2, KCNK12, DDX15, CDK6, and LAMA3, and losses of CDH1, GLTSCR2, EGR1, CTSB, GATA3, and SULT2A1. These genes seem to be responsible for developing MPNSTs. The concordance rate between metaphase CGH and microarray CGH was 66%. Metaphase CGH was useful for identifying chromosomal alterations before applying microarray CGH.

Epithelioid malignant peripheral nerve sheath tumor involving maxillary sinus

We present a case of epithelioid malignant peripheral nerve sheath tumor (MPNST) located in the maxillary sinus region in a young man. The clinical history was short, but at admission the neoplastic infiltration was so extensive that only diagnostic biopsy was performed. The patient received palliative treatment and died 6 months later. Histologically, the neoplasm had a predominant epithelioid component. Neoplastic tissue was vimentin, S-100, Cam 5.2 and neuron-specific enolase positive. P53 protein reaction was found in 6% of the cells and the proliferation index assessed with Ki-67 was 52%. An appropriate immunohistochemical panel was essential for the final diagnosis of this epithelioid malignant tumor, with the location rather unusual for MPNST.

Case report: Malignant peripheral nerve sheath tumor of the uterine cervix treated with radical vaginal trachelectomy

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNST) are rare tumors which occur primarily in major nerve trunks and most commonly in patients with neurofibromatosis. Only seven prior cases of these tumors arising in the uterine cervix have been reported, all of which were treated by hysterectomy.

CASE

We report a 22-year-old woman with MPNST of the uterine cervix which recurred after loop electrocautery excision and had positive margins on cone biopsy. She was treated definitively with radical trachelectomy and is well with no sign of recurrence 20 months later.

CONCLUSIONS

MPNST of the uterine cervix is a rare, but potentially aggressive neoplasm. This is the first case of such a tumor treated successfully with preservation of the patients fertility.

Malignant peripheral nerve sheath tumor arising in association with the sural nerve

Malignant peripheral nerve sheath tumor is a rare sarcoma of peripheral nerves found most often in deep soft tissue. This aggressive tumor is difficult to diagnose clinically and must be surgically excised for therapy. An incisional biopsy will allow for testing and in most cases, diagnosis. The authors present a case of a 39-year-old African American woman with malignant peripheral nerve sheath tumor in association with the sural nerve. The tumor was surgically removed and sent for pathologic studies. The patient reported to her first postoperative appointment and was referred to an oncologist for follow-up. Despite multiple attempts at contacting the patient and explaining the prognosis of the diagnosis, the patient refused further follow-up care including referral to an oncologist.

Endonasal approach for frontobasal malignant nerve sheath tumor: a case report

Malignant peripheral nerve sheath tumors (MPNST) are rarely encountered in the paranasal sinuses and frontal skull base. We present histopathological findings, cytometric DNA measurements, and the preliminary results of comparative genomic hybridization analysis of a 46-year-old male patient with a frontobasal MPNST. The tumor was resected via the endonasal approach. No tumor recurrence was detected during a follow-up of three years. Rhinologists are being more frequently involved in endonasal tumor resection.

Intrathoracic paraspinal malignant peripheral nerve sheath tumor

Schwannoma is the most common nerve sheath tumor in the posterior mediastinum, whereas intrathoracic paraspinal malignant peripheral nerve sheath tumor (MPNST) is quite rare. Both benign and malignant nerve sheath tumors may be symptomatic, rendering clinical differentiation of limited utility. On radiographic imaging, erosion of the ribs and vertebral bodies, irregularity in contour, and inhomogeneity in attenuation are not sufficiently reliable for diagnosis of MPNST. Histologically, MPNSTs reveal hypercellularity, nuclear atypia, and mitotic activity. Surgical resection is the main modality of treatment. Postoperative radiation therapy for MPNST has led to a significant reduction in local recurrence. The prognosis is unfavorable. Herein, we present an unusual case of a posterior mediastinal mass in a 50-year-old female with delayed diagnosis of 2 years. After surgical intervention, the histologic finding was MPNST. Postoperative radiation therapy was applied because of incomplete resection. The follow-up chest computed tomography 5 months later revealed a residual soft tissue mass with significant reduction in size over the parathoracic spine area. No neurologic sequelae were identified after surgery.

Pediatric malignant peripheral nerve sheath tumor: the Italian and German soft tissue sarcoma cooperative group

PURPOSE

To assess the value of chemotherapy and radiotherapy in children with malignant peripheral nerve sheath tumors (MPNSTs) and to identify risk factors associated with outcome.

PATIENTS AND METHODS

A total of 167 untreated eligible patients enrolled onto the Italian and German studies between 1975 and 1998 entered this analysis. Seventeen percent of patients had neurofibromatosis type 1 (NF1). Chemotherapy was administered to 74% of patients; radiotherapy was administered to 38% of patients.

RESULTS

With a median follow-up of 7 years, 5-year overall survival (OS) and progression-free survival (PFS) were 51% and 37%, respectively. The 5-year OS and PFS by Intergroup Rhabdomyosarcoma Study (IRS) groupings were as follows: group I, 82% and 61%; group II, 62% and 37%; group III, 32% and 27%; group IV, 26% and 21%, respectively. Univariate analysis identified IRS groups, size, invasiveness, primary site, age, and presence of NF1 as prognostic factors; multivariate analysis identified absence of NF1, tumor invasiveness T1, IRS groups I to II and extremity of primary site as independent favorable factors for OS. A trend was observed toward a benefit from radiotherapy after initial gross resection. The overall response rate to primary chemotherapy, including minor responses, in group III patients was 45%.

CONCLUSION

MPNST is an aggressive tumor for which complete surgical resection is the mainstay of successful treatment. Postoperative radiotherapy may have a role in improving local control in patients with minimal residual tumor. The reported responses to primary chemotherapy suggest that it may be effective in patients with tumor considered unresectable at diagnosis.

Of all the nerve! A subcutaneous forelimb mass on a cat

A 16-year-old, male, neutered cat had a 2.5 X 1.5 cm mass on the medial aspect of the right carpus. Cytologic examination of a fine-needle aspirate of the mass indicated a markedly pleomorphic population of plasmacytoid to histiocytic-appearing cells. The cytologic diagnosis was malignant neoplasia of probable mesenchymal or round cell origin. The right forelimb was surgically removed and the scapular, axillary, and prescapular lymph nodes were excised. Malignant fibrous histiocytoma was tentatively diagnosed histologically; however, the tumor cells subsequently were found to be negative for histiocytic (MAC 387, antitrypsin), T-cell (CD3), and B-lymphocyte (immunoglobulin light chains, Ly 5/CD45R) markers, and positive for glial fibrillary acidic protein, vimentin, and S-100. Based on the immunohistochemical results, the diagnosis was modified to malignant peripheral nerve sheath tumor (PNST). Six months after surgery, the cat was reported to be well and had no evidence of metastasis. PNSTs are rare tumors in cats, and are considered as synonymous with schwannomas, neurofibrosarcomas, and hemangiopericytomas. In this cat, the plasmacytoid and pleomorphic appearance of the PNSTcells in cytologic and histologic specimens was unusual, and made it difficult to reach an accurate diagnosis without immunocytochemistry.

Nerve Sheath Myxoma

This report describes the clinicopathologic findings in 57 cases of nerve sheath myxoma. Our study group included 34 males and 23 females, ranging from 8 to 72 years of age at the time of their first surgical procedure (mean, 36 years; median, 34 years). The patients typically presented with solitary, superficial, multinodular masses in the 0.5- to 2.5-cm size range. Eighty-six percent of cases occurred in the extremities, with the most common locations being the hand/fingers (n = 22), knee/pretibial region (n = 10), and ankle/foot (n = 7). Only 7 cases (12.3%) involved the trunk or head and neck region. The tumors were generally slow growing, and often, they were present for many years before surgical resection was sought. In the majority of instances, the lesions were painless. Histologically, the tumors involved the dermis and/or subcutis, and they formed distinct multinodular/multilobular masses with abundant myxoid matrix and a peripheral fibrous border. All cases had small epithelioid Schwann cells in corded, nested, and/or syncytial-like aggregates, a variable number of Schwann cells with a ring-like appearance, and scattered spindled and stellate-shaped Schwann cells. These cells often had cytoplasmic-nuclear invaginations, and they were immunoreactive for S-100 protein, glial fibrillary acidic protein, neuron specific enolase, and CD57. They were also bordered by collagen IV. Epithelial membrane antigen-positive perineurial cells were typically present in small numbers, primarily in the fibrous tissue directly adjacent to the myxoid nodules. CD34-positive intraneural fibroblasts were generally sparse. Mitotic figures were uncommon. All cases were initially managed by simple excision, and in almost all instances, tumor extended to the tissue edge. Follow-up information is available for 34 patients (follow-up range, 8 months to 28 years; median follow-up interval, 14 years 3 months). Sixteen patients (47%) had one (n = 11) or more (n = 5) local recurrence of their tumor, and 2 additional patients had findings suspicious for a recurrence. Nerve sheath myxomas are morphologically distinct peripheral nerve sheath tumors with a peak incidence in the fourth decade of life and a strong predilection for the extremities. These tumors have a relatively high local recurrence rate when managed by simple local excision. They appear to be unrelated to so-called cellular and mixed-type neurothekeomas.

Expression and Function of Somatostatin Receptors in Peripheral Nerve Sheath Tumors

Although somatostatin receptors have been detected in many normal and neoplastic tissues, little is known of their expression and function in peripheral nerve tumors. In the present study, we examined the expression of all 5 somatostatin receptor subtypes (sst1-5) in 3 normal peripheral nerves, 3 traumatic neuromas, 27 schwannomas, 18 neurofibromas, and 177 malignant peripheral nerve sheath tumors (MPNSTs) by immunohistochemistry as well as by Western blot and reverse transcriptase-polymerase chain reaction investigations in 2 normal peripheral nerves, one neurofibroma, 5 schwannomas, and 5 MPNSTs. Immunoreactive somatostatin receptors were not detectable in normal peripheral nerve and in nonneoplastic Schwann cell proliferations. In contrast, sst2A mRNA and protein was present in 89% of schwannomas. This receptor subtype was less frequently detected in neurofibromas (22%) and MPNSTs (15%). Interestingly, sst4 was seen in 32% of MPNSTs and was almost exclusively expressed in this malignant tumor type. In support of a role in Schwann cell tumor growth control by somatostatin was the observation of induced internalization of sst2A and inhibition of cell proliferation in an NF1-associated MPNST cell line. Moreover, administration of an sst2A-selective agonist resulted in induction of MPNST cell apoptosis. We conclude that peripheral nerve sheath tumors often express at least one functional somatostatin receptor. Furthermore, our findings suggest a potential clinical role for somatostatin receptor agonists in tumor imaging and/or treatment of schwannomas and MPNSTs.

Mucosal benign epithelioid nerve sheath tumors

Mucosal nerve sheath tumors have been well described in the gastrointestinal tract and other mucosal sites. In a series of mucosal biopsies, we have encountered a distinct subset of mucosal peripheral nerve sheath tumors characterized by small epithelioid cells and a benign clinical course. Such epithelioid nerve sheath tumors have been observed as a component of a larger study of colorectal "schwannomas," but herein we describe them in detail. A series of 7 of these lesions detected on mucosal biopsies (6 colonic, 1 bladder) was received by a single large institution in consultation material. The histologic and clinicopathologic features of the cases were reviewed. The mean age at presentation was 58.6 years with a slight female predominance (4 females, 3 males). Five of the colonic lesions were from the left colon and one from the right colon. The bladder biopsy was from the bladder neck. All of the colonic lesions were discovered as small (0.2-1.0 cm) polyps during the time of colonoscopy (3 at the time of routine screening, 2 for the workup of occult blood in the stool). The bladder neck mass was seen on bladder ultrasound after the patient presented with vaginal bleeding. None of the patients had a known history of neurofibromatosis. Histologically, the lesions showed an infiltrative growth pattern and were composed of spindled to predominantly epithelioid cells arranged in nests and whorls. The epicenters of the lesions were located in the lamina propria and extended to the superficial submucosa. The proliferating cells had uniform round to oval nuclei with frequent intranuclear pseudoinclusions and eosinophilic fibrillary cytoplasm. No mitoses were seen. All lesions expressed diffuse S-100 protein, and 3 of 5 lesions stained showed CD34 labeling in supporting cells. All were negative for CD117. All 5 lesions tested were negative for calretenin, while SM31 showed no intralesional neuraxons. One lesion was stained for epithelial membrane antigen and was negative. One lesion was associated with superficial mucosal erosion, and 1 had an inflammatory infiltrate predominantly composed of eosinophils. On follow-up of 5 patients, none has had any symptoms or recurrence of disease. Mucosal epithelioid nerve sheath tumors are a rare entity characterized by prominent epithelioid round to oval cells with an infiltrative growth pattern. These lesions are often discovered incidentally and have a benign clinical course.

Superficial malignant peripheral nerve sheath tumor: a rare and challenging diagnosis

We reviewed the clinicopathologic features of 5 cases of malignant peripheral nerve sheath tumor (MPNST) manifesting in superficial locations associated with cutaneous neurofibromas (4 cases) or superficial peripheral nerve (1 case). Four cases had spindle cell morphologic features and were at least focally positive for S-100 protein, whereas the associated benign neural elements had more extensive S-100 immunoreactivity. The single epithelioid case was diffusely and strongly positive for S-100 protein. Melanoma markers, epithelial membrane antigen, glial fibrillary acidic protein, neurofilament, pancytokeratin (AE1/AE3), CD34, smooth muscle actin, and desmin were negative in all cases. There were no local recurrences, but 3 patients died of metastatic disease within 2 to 30 months (median, 21 months). MPNSTs can occur in a superficial location and may have an aggressive clinical course. Immunohistochemical markers are helpful in excluding other lesions in the differential diagnosis. However, identification of a benign precursor or origin from a nerve may be the most definitive way to properly classify these rare lesions.

Evaluation of perineurial differentiation in epithelioid sarcoma

AIMS

To investigate the differentiation pattern of epithelioid sarcoma in terms of perineurial and endothelial differentiation, and its relationship to that of meningioma.

METHODS AND RESULTS

Nine cases of epithelioid sarcoma and five cases of meningioma were studied in an immunohistochemical analysis of 'perineurial' antigens [GLUT-1, claudin-1, epithelial membrane antigen (EMA) and VE-cadherin] and of 'endothelial' antigens not present on normal perineurium (CD34, CD31, Fli-1). Both epithelioid sarcoma and meningioma showed frequent expression of the perineurial markers GLUT-1, claudin-1 and EMA. VE-cadherin was identified in one of five meningiomas, and in the only case of epithelioid sarcoma in which suitably fixed material was available. CD34 was expressed by all epithelioid sarcomas studied but by none of the meningiomas. Fli-1 was present in a substantial majority of epithelioid sarcomas and by all the meningiomas. CD31 was not detected in any epithelioid sarcoma or meningioma.

CONCLUSIONS

The results were evaluated in the context of previous immunohistochemical, ultrastructural and genetic studies and suggest that epithelioid sarcoma may be a form of malignant perineurioma with a range of differentiation (epithelial features) akin to that seen in meningioma, reflecting the close relationship between perineurium and meningothelium.

Overexpression of Midkine in malignant peripheral nerve sheath tumor cells inhibits apoptosis and increases angiogenic potency

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue tumors arising sporadically although more frequently in patients with Neurofibromatosis type 1. Prognosis remains dismal as chemo- and radiotherapy have not been shown to be successful. The heparin-binding growth factor, Midkine (MK), is implicated in the tumorigenesis of benign and plexiform neurofibromas, and thereof arising MPNSTs. MK is mitogenic, anti-apoptotic, angiogenic and can promote tumorigenicity in several cell types. Thus, we investigated the role of MK in malignant biology and tumorigenicity in MPNSTs by stable transfection into MPNST cell lines. Overexpression of MK in the MPNST cell line, S462, increased cell viability and protected cells from apoptosis under serum deprivation, but did not induce proliferation. In addition, MK-transfected S462 cells were partially protected from vincristine-induced cell death. Conditioned medium of MK-transfected S462 cells was a potent mitogen for human umbilical venous endothelial cells. Furthermore, MK overexpression in S462 cells was accompanied by higher levels of VEGF mRNA. Yet, stable overexpression of MK in S462 as well as in ST88-14 cells was not sufficient to promote xenograft tumor growth in nude mice. However, increasing survival and enhanced angiogenic potency of MK-transfected S462 cells highlight the importance of developing specific inhibitors for MK as part of new therapeutic concepts against MPNSTs.

Symptoms associated with malignancy of peripheral nerve sheath tumours: a retrospective study of 69 patients with neurofibromatosis 1

BACKGROUND

Neurofibromatosis 1 (NF1) is a common genetic disorder with variable clinical manifestations and an unpredictable course. Plexiform neurofibromas are common complications of NF1. Their malignant transformation is the main cause of mortality in adult patients with NF1.

OBJECTIVES

To identify clinical factors associated with malignant transformation of plexiform neurofibromas.

METHODS

Using the database of our neurofibromatosis clinic we included in a retrospective study all patients with NF1 having at least one peripheral nerve sheath tumour for which they underwent surgery or surgical biopsy. Predictive values for malignant transformation of three clinical symptoms, i.e. pain, enlargement of mass and neurological symptoms, were evaluated in association with histological parameters.

RESULTS

Of 69 patients studied, 48 had at least one plexiform neurofibroma and 21 had a malignant peripheral nerve sheath tumour. Only enlargement of the tumour had high negative and positive predictive values for malignant transformation: 0.92 and 0.95, respectively. In multivariate analysis, tumour enlargement was independently associated with malignant transformation (odds ratio 167.8, 95% confidence interval 14.0-2012.1).

CONCLUSIONS

From a practical point of view, pain, neurological deficit and enlargement of a pre-existing peripheral nerve sheath tumour in NF1 must lead to deep surgical biopsy to rule out malignant transformation.

Perineurioma of the stomach. A rare spindle cell neoplasm that should be distinguished from gastrointestinal stromal tumor

We report on the first case of benign perineurially differentiated peripheral nerve sheath tumor (perineurioma) presenting as a bleeding gastric mass in a 30-year-old, previously healthy woman with no signs or stigmata of von Recklinghausen's disease or other primary tumor at time of presentation. Gastric resection specimen revealed an ulcerated moderately cellular mesenchymal tumor consisting of elongated wavy spindle cells arranged in a fascicular and sheet-like pattern with focal whorling and occasional alternation of dark staining cellular and light staining hypocellular areas. Tumor cells were strongly immunoreactive for epithelial membrane antigen, CD56 (N-CAM), and vimentin, but were negative for S-100-protein and other lineage-specific epithelial, mesenchymal, hematolymphoid, and reticulo-histiocytic markers. CD117 revealed numerous positive staining mast cells, but the lesional cells were not reacting. We presume that the combined histological and immunohistochemical profiles of this unusual gastric neoplasm are consistent with a diagnosis of perineurioma with a probably benign biological behavior. To our knowledge, this is the first report of gastric perineurioma, an extremely rare mesenchymal lesion that should be considered among the differential diagnoses of gastrointestinal stromal tumor, especially the so-called KIT-negative GIST. Gastrointestinal perineuriomas might be under-recognized, as our case was initially diagnosed as a benign GIST.

Infiltrating retiform perineurioma: a case report

Retiform perineurioma is a rare distinct histologic subtype of benign soft tissue perineurioma. We report 1 case of retiform perineurioma with a superficial invasion of the adjacent skeletal muscle. The patient was a 34-year-old woman with a neoplasm located between the deltoid muscle and the biceps. Histologically, the tumor was nonencapsulated, composed exclusively of perineurial cells without cytologic and tissue atypia. There were focal areas in which the neoplastic cells infiltrated the muscle tissue, widely separating the bundles. This case may represent a diagnostic pitfall as it can be confused with a malignant perineurioma.

Malignant triton tumor (MTT) of the neck

Malignant Triton Tumor (MTT) is a rare, malignant periphere nerve sheath tumor with rhabdomyoblastic differentiation. One third of described MTT's were located at the head and neck region. One third of these are associated with neurofibromatosis type 1. MTT most often appears in the third decade. MTT's are very aggressive tumors with early metastases and the overall survival is poor (26%). Therefore, early diagnosis and correct treatment is of utmost importance. We report a case of MTT of the left supraclavicular region in a 41-year-old man. We present the pathological findings, both light and immunohistochemically.

Activation of the neuregulin-1/ErbB signaling pathway promotes the proliferation of neoplastic Schwann cells in human malignant peripheral nerve sheath tumors

Patients with neurofibromatosis type 1 develop aggressive Schwann cell neoplasms known as malignant peripheral nerve sheath tumors (MPNSTs). Although tumor suppressor gene mutations play an important role in MPNST pathogenesis, it is likely that dysregulated signaling by as yet unidentified growth factors also contributes to the formation of these sarcomas. To test the hypothesis that neuregulin-1 (NRG-1) growth factors promote mitogenesis in MPNSTs, we examined the expression and action of NRG-1 in human MPNSTs and neurofibromas, the benign precursor lesions from which MPNSTs arise. Multiple alpha and beta transmembrane precursors from the class II and III NRG-1 subfamilies are present in both tumor types. Neoplastic Schwann cells within these neoplasms variably express the erbB kinases mediating NRG-1 responses (erbB2, erbB3 and/or erbB4). Human MPNST cell lines (Mash-1, YST-1, NMS-2 and NMS-2PC cells) similarly coexpress multiple NRG-1 isoforms and erbB receptors. These MPNST lines are NRG-1 responsive and demonstrate constitutive erbB phosphorylation. Treatment with PD168393 and PD158780, two structurally and mechanistically distinct erbB inhibitors, abolishes erbB phosphorylation and reduces DNA synthesis in these lines. These findings suggest that autocrine and/or paracrine NRG-1/erbB signaling promotes neoplastic Schwann cell proliferation and may be an important therapeutic target in neurofibromas and MPNSTs.

Cytogenetic Aberrations in Perineurioma

Only two karyotypes of perineurioma have previously been reported, 46XX,del(10)(q22q24),der(10),del(22)(q11-12q?)/47, idem,+der(10) (in a sclerosing perineurioma of the finger) and 45,XX,add(14)(p13),-22,add(22)(q11.2) (in an intraneural perineurioma). We investigated the clinicopathologic and cytogenetic findings in four consecutive perineuriomas in children, including two small (< or =1 cm) digital sclerosing perineuriomas, a 2-cm intraneural perineurioma, and a 16-cm abdominal soft tissue perineurioma. All lesions showed plump perineurial cells in a complex whorled configuration. Immunohistochemical (strong EMA immunostaining in all cases) and ultrastructural (in three of three lesions examined) evidence of perineurial differentiation was present. The sclerosing perineuriomas showed 46,XY,t(2;10)(p23;q24) and 47,XX,add(3)(q23),add(6)(q21),-5,-9,-10,-22,+mar1,+mar2,+mars; the intraneural tumor showed 46,XX,add(2)(q11.2),add(3)(q12); and the abdominal soft tissue perineurioma showed 46,XX,t(8;9)(q13;q22). Metaphase FISH analysis for an ALK gene rearrangement in the sclerosing perineurioma with t(2;10) was negative; the ALK signal remained on the der(2). We conclude that perineuriomas display mostly simple karyotypes, characterized by one or few chromosomal rearrangements or numerical changes. In conjunction with the previously published sclerosing perineurioma karyotypes, the findings of chromosome 10 aberrations, t(2;10)(p23;q24) and monosomy 10 in two sclerosing perineuriomas, indicate that rearrangements and/or deletions of 10q are a consistent finding in this variant of perineurioma. The findings also expand previous assertions that chromosome 22 abnormalities are pathogenetic in perineurioma and suggest that diverse genetic tumorigenic mechanisms may exist, possibly depending on the subtype.

Management of a sporadic malignant subfrontal peripheral nerve sheath tumor

Malignant subfrontal (olfactory) peripheral nerve sheath tumors (MPNSTs) are exceedingly rare. Although meningiomas are the most common subfrontal extra-axial lesions, it is important to recognize that MPNSTs, which are radiographically similar to meningiomas, can also be present in this location. MPNSTs require more aggressive surgical and postoperative management than meningiomas. In this paper, we describe a patient with a subfrontal MPNST with unusual histological characteristics and present a review of the literature. A 49-year-old woman presented with chronic sinusitis and progressive headaches. A neurological examination revealed left-sided anosmia. Brain-imaging studies revealed a large left subfrontal mass with extension into the frontal and ethmoid sinuses and the nasal cavity. The patient underwent both a bifrontal transbasal craniotomy and a transnasal approach for an attempt at total resection of both the intradural and extradural components of the MPNST. The patient was treated postoperatively with radiation therapy, and had no evidence of recurrence at her follow-up examination 1-year after treatment. Subfrontal PNSTs are extremely rare and usually benign. The specific cell and nerve of origin for these tumors remains unknown. Our case shows that these rare lesions can present as a malignant variant and thus require aggressive surgical and postoperative management to provide long-term tumor control.

Atypical midface tumor complicating nevus of ota

In the differential diagnosis of midface masses, the nevus of Ota (also called oculodermal melanocytosis) is a rare entity. We present a case of a young white man, who lost his left eye function by progression of a melanocytotic lesion involving the ophthalmic (VI) and maxillary (VII) divisions of the trigeminal nerve. The time course, distribution along the trigeminal nerve, and characteristic MR signal intensities of the lesion, in correlation with the clinical, ophthalmological, and dermatological findings, point to the correct diagnosis.

Spinal Cord Metastasis of a Non-neurofibromatosis Type-1 Malignant Peripheral Nerve Sheath Tumor: An Unusual Manifestation of a Rare Tumor

Malignant peripheral nerve sheath tumors are rare spindle-cell sarcomas derived from Schwann cells or pluripotent cells of the neural crest. They arise from the spinal roots, peripheral nerves, brachial and lumbosacral plexi, cranial nerves and terminal nerve fibers within soft tissue, intestine, lung and bone. These tumors recur either locally, or metastasize distally. Most of these tumors occur in association with neurofibromatosis type 1. Spinal cord metastasis from malignant nerve sheath tumors associated with neurofibromatosis type 1 is very rare. We describe a rare case of near-total spinal cord metastasis in a patient with malignant nerve sheath tumor in the absence of neurofibromatosis, and highlight the microscopic findings and natural history of this disease process.