Intraspinal pigmented schwannoma with malignant progression

Schwannomas and their pathogenesis

Schwannomas may occur spontaneously, or in the context of a familial tumor syndrome such as neurofibromatosis type 2 (NF2), schwannomatosis and Carney's complex. Schwannomas have a variety of morphological appearances, but they behave as World Health Organization (WHO) grade I tumors, and only very rarely undergo malignant transformation. Central to the pathogenesis of these tumors is loss of function of merlin, either by direct genetic change involving the NF2 gene on chromosome 22 or secondarily to merlin inactivation. The genetic pathways and morphological features of schwannomas associated with different genetic syndromes will be discussed. Merlin has multiple functions, including within the nucleus and at the cell membrane, and this review summarizes our current understanding of the mechanisms by which merlin loss is involved in schwannoma pathogenesis, highlighting potential areas for therapeutic intervention.

Clinical analysis of primary melanotic ependymoma in the central nervous system: case series and literature review

BACKGROUND

Melanotic ependymoma (ME) is an extremely rare subset of ependymoma characterized by cytoplasmic and extracellular deposition of melanin, with no case series having been reported to date. The aim of this study was to analyze the clinical manifestations, pathological and radiological features, treatment, and follow-up data, and to discuss the diagnosis, management and prognosis of ME.

METHODS

We retrospectively reviewed the clinical and imaging data of six patients with primary ME. The diagnosis was based on radiological and pathological criteria. All the patients were treated surgically with gross total resection. The preoperative and postoperative neurological states of the patients were analyzed. All the follow-up data were obtained from office visits, and the long-term outcomes are presented and discussed.

RESULTS

Patients presented with nonspecific symptoms. On magnetic resonance imaging (MRI), although a characteristic signal variation could be found reflecting the melanin component, individual appearances varied widely and were related to the content and distribution of melanin in the ME lesions. The characteristic ependymoma-related pathological appearance and specific immunostaining for glial fibrillary acidic protein and antimelanoma monoclonal antibody were revealed. During a mean follow-up period of 46.8 months, no local recurrences or distant metastases were observed.

CONCLUSIONS

The accurate diagnosis of ME depends on pathology. The histological grading used for ependymoma can be applied. Most MEs have a relatively benign course. Complete surgical resection alone is the treatment of choice for low-grade MEs, and the outcome may be favorable. Postoperative adjuvant radiotherapy can be considered for lesions with histologically anaplastic features.

Genetic predisposition to peripheral nerve neoplasia: diagnostic criteria and pathogenesis of neurofibromatoses, Carney complex, and related syndromes

Neoplasms of the peripheral nerve sheath represent essential clinical manifestations of the syndromes known as the neurofibromatoses. Although involvement of multiple organ systems, including skin, central nervous system, and skeleton, may also be conspicuous, peripheral nerve neoplasia is often the most important and frequent cause of morbidity in these patients. Clinical characteristics of neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2) have been extensively described and studied during the last century, and the identification of mutations in the NF1 and NF2 genes by contemporary molecular techniques have created a separate multidisciplinary field in genetic medicine. In schwannomatosis, the most recent addition to the neurofibromatosis group, peripheral nervous system involvement is the exclusive (or almost exclusive) clinical manifestation. Although the majority of cases of schwannomatosis are sporadic, approximately one-third occur in families and a subset of these has recently been associated with germline mutations in the tumor suppressor gene SMARCB1/INI1. Other curious syndromes that involve the peripheral nervous system are associated with predominant endocrine manifestations, and include Carney complex and MEN2b, secondary to inactivating mutations in the PRKAR1A gene in a subset, and activating mutations in RET, respectively. In this review, we provide a concise update on the diagnostic criteria, pathology and molecular pathogenesis of these enigmatic syndromes in relation to peripheral nerve sheath neoplasia.

Melanotic schwannoma: a case with strong CD34 expression, with histogenetic implications

Melanotic schwannomas (MS) are rare tumors composed of cells with both schwannian and melanocytic features, which usually occur in the setting of Carney's Complex. We describe a case of a 36-year-old male who presented with a mass that was attached to the vertebral body as well as the nerve roots of L2 and L3. Immunohistochemical positivity for S-100, HMB-45, and Pan-melanoma markers, as well as characteristic morphologic and ultrastructural findings, suggested that the lesion was a MS. The interest in this case lies in the fact that this case of MS showed strong CD34 expression, a marker that is generally negative in melanocytic tumors. We discuss the biologic significance of the high CD34 expression by the tumor cells and attempt to shed light on the histogenesis of this rare entity.

Spinal extradural schwannoma

OBJECT

The authors endeavor to define the clinical and surgery-related profile of spinal nerve sheath tumors located in the extradural space outside both the dural sac and, apparently, the nerve roots' sleeve.

METHODS

A series of 24 extradural schwannomas was retrospectively selected after reviewing the notes of spinal nerve sheath tumors surgically treated at La Sapienza University of Rome. Clinical data, tumor-related characteristics, and outcome were analyzed. Women predominantly harbored these tumors. On admission sensory nerve root dysfunction was infrequently reported, whereas pyramidal tract deficits were often present. The tumor, generally large, was most frequently located in the intermediate thoracic segments and high cervical region; only one was reported in the lumbosacral region. Considerable erosion of vertebral bodies was reported in almost one third of the cases. In four patients eloquent nerve roots, that of C-5 in three and that of S-1 in one, were involved with the tumor. Radical tumor resection, with preservation of the nerve roots, was possible in several cases, whereas in two patients manipulation and resection of the C-5 root produced transient and permanent, respectively, root palsy. At follow-up examination patients for whom walking was impossible before surgery were now able to walk.

CONCLUSIONS

Extradural schwannomas can be distinguished from other nerve sheath tumors growing inside the spinal canal by their clinicoradiological features and unlikely nerve root origin. After surgery, recovery from pyramidal tract deficits, even severe, is noteworthy; in the authors' experience, however, resection of an involved appendicular root is more likely to result in a permanent and significant radicular deficit.

Melanotic schwannoma with drop metastases to the caudal spine and high expression of CD117 (c-kit)

Melanotic schwannomas (MS) are tumors of Schwann cell origin characterized by cytoplasmic deposition of melanin. The authors present the case of a 61-year-old man who experienced progressive weakness of the lower extremities over 2 years. This was followed by acute deterioration, which prompted his presentation. MRI of the spine revealed an intradural, extramedullary lesion at the level of T7 with severe spinal cord compression. More caudally, there was involvement of the lumbar spine with drop metastases to the conus medullaris and cauda equina. The patient underwent thoracic laminectomy for tumor resection. A diagnosis of MS was made based on histologic morphology, immunohistochemical profile, and ultrastructural findings. In this report, the authors describe a MS with expression of CD117 (c-kit) and review the literature pertaining to this condition.

Immunohistochemical and Ultrastructural Comparative Study of External Lamina Structure in 31 Cases of Cellular, Classical, and Melanotic Schwannomas

Unlike most soft tissue tumors, schwannoma is characterized by the presence of distinct linear, frequently duplicated external lamina (EL). Although electron microscopy remains the gold standard for demonstrating this unique feature and distinguishing its morphologic variants from mimickers, the use of two anti-EL antibodies, laminin and type IV collagen, appears to supersede electron microscopy in terms of current practice. To determine whether immunohistochemical expression correlates with ultrastructural findings, 10 cellular schwannomas, 18 classic schwannomas, and 3 melanotic schwannomas were evaluated ultrastructurally and immunohistochemically using antibodies to type IV collagen and laminin. Immunohistochemically, a moderate to strong intensity in more than 50% of tumor cells was detected using either antibody in most cases of cellular schwannomas (70%), the Antoni A areas of classic schwannomas (78%), and melanotic schwannomas (67%). Ultrastructurally, the presence of diffusely continuous, duplicated EL was observed in 30% of cellular schwannomas and 56% of classic schwannomas, while 50% of cellular schwannomas and 22% of classic schwannomas showed either continuous simple EL or discontinuous but duplicated EL alone. In addition, two cellular schwannomas (20%) and four classic schwannomas (22.2%) had only a simple layer of EL in focal areas. In contrast to the distinct immunostaining surrounding individual cells seen in the former two subtypes, all three melanotic schwannomas displayed a biphasic-staining pattern of the EL (ie, individual cell and nested), which was confirmed at the ultrastructural level. The authors found a significant difference in intensity between the Antoni A and B areas of classic schwannomas using both laminin and type IV collagen. In addition, the intensities of laminin and type IV collagen in the Antoni A areas of classic schwannomas were significantly stronger compared with those of cellular schwannomas. Nevertheless, there was no significant difference either between two antibodies or between cellular and classic variants with regard to the extent of immunoreaction. Only in classic schwannomas did the extent of immunoreaction against both laminin and type IV collagen correlate significantly with the ultrastructural EL distribution pattern (diffusely continuous vs. discontinuous). However, this association was not detected in cases of cellular schwannomas. On the other hand, the intensities of laminin and type IV collagen did not correlate with the ultrastructural thickness of EL, irrespective of the morphologic subtypes. In conclusion, both type collagen IV and laminin are still reliable markers of EL in various types of schwannomas. Schwannomas exhibiting a monolayered EL are as strong in immunoreaction as those displaying reduplicated/thickened EL, indicating that a single layer of EL is thick enough to be identified by both antibodies with sufficient sensitivity. The peculiar biphasic EL pattern seen in melanotic schwannoma remains under-recognized, which may lead to misdiagnosis as malignant melanomas, especially in limited biopsy specimens.

Spinal melanotic schwannoma: a tumour with poor prognosis

AIM

To clarify the prognosis of melanotic schwannoma. This is a rare tumour which is generally considered as a benign lesion, reported in many cases with a short follow-up only.

METHODS AND RESULTS

Five cases of spinal melanotic schwannoma were retrospectively studied. The tumours were examined using standard histological, immunohistochemical and ultrastructural methods. No features of malignancy (high mitotic count, atypia or necrosis) were found in the primary tumours. The follow-up period ranged from 3 to 7 years. Malignant clinical behaviour was clear-cut in four cases: three patients died from metastases to various sites and one presented several discrete spinal tumours of the same type seven years after the first operation. Only one patient presented no recurrence and was free of disease 6 years after initial diagnosis. The review of 57 cases of the literature (including our cases), showed that 15% of the cases had recurrences and 26.3% were complicated by metastasis. Only 53% of the cases followed for more than 5 years, were free of disease vs. 67.5% of the cases with shorter follow-up. Twenty additional cases had no follow-up.

CONCLUSION

Appropriate long-term follow-up is required for all melanotic schwannomas, as it may recur or metastasize after more than 5 years, even in the absence of overt malignant histological features.

Primary cervical melanoma with brain metastases. Case report and review of the literature

Primary intramedullary melanoma is a very rare tumor that occurs most frequently in the middle or lower thoracic spinal cord. The authors present a case of primary cervical cord melanoma that developed in a 62-year-old man who was surgically treated and subsequently underwent radiation therapy. Clinical and histogenetic features of this neoplasm and results of chemo-. radio-, and immunotherapy are reported. Both "dysembryogenetic" and "mesodermal" hypotheses on the origin of primary spinal melanoma are discussed.

Psammomatous melanotic schwannoma of a spinal nerve root. Relationship with the Carney complex

A 36-year-old man had an oval, black, extradural tumor partly removed from the left C4 spinal root, with total removal 4 months later. In both specimens, most tumor cells were spindle-shaped. A few cells were large, epithelioid-like, with a prominent nucleolus. Mitoses were rarely seen. Many tumor cells contained coarse or fine granules of a brown pigment. Such cells were immunopositive for S-100 protein and HMB-45. Additionally, psammoma bodies were numerous in certain areas, indicating a diagnosis of psammomatous melanotic schwannoma (PMS). Periumbilical spotty pigmentation was found in the patient and in six of his siblings and their mother. The search for cardiac myxoma and endocrine overactivity was negative in the patient. Features of Carney's complex must be sought in a patient with PMS and in their primary relatives. So far, more than 150 patients and seven families with Carney's complex have been reported.

Primary spinal malignant schwannoma

Malignant schwannomas are uncommon primary tumours of nerve sheath origin. They are rarely found within the spine and spinal canal, and little is known about their management in this unusual location. We describe the presentation of three patients with primary spinal malignant schwannomas and discuss the surgical management.

Melanotic ganglioglioma of the pineal region

A melanotic ganglioglioma was biopsied in the pineal region of a 12-month-old girl who preoperatively underwent a ventriculo-peritoneal shunt for hydrocephalus and postoperatively received radiotherapy. The tumor was subtotally excised when the girl was 7 years and 4 months of age. Histologically, it demonstrated mature neurons in disorganized clusters and in well-differentiated cerebrum-like tissue, rare binucleated neurons, glia similar to normal gray matter, and bands of fibrous tissue containing heavily pigmented cells. Ultrastructurally, melanosomes of stages I to IV were identified in the pigmented cells. An origin involving retinal differentiation of the primitive pineal gland was not supported; the tumor was negative for both retinal S-antigen (MAbA9-C6) and cellular retinal-binding protein (CRALBP). This report demonstrates the ability of a cerebral neoplasm to contain neurons, glia, and melanin-containing cells; all of which are neuroectodermally derived.